Emergency Room Hematology CAQ

One Step Further Question: What would be the expected lactate dehydrogenase (LDH) value in this patient?

Answer: We would expect it to be elevated, as a marker of hemolysis.

Question: What red blood cell disorder has a characteristic increase in mean corpuscular hemoglobin concentration (MCHC)?

Answer: Spherocytosis.

Question: What is a rouleaux formation?

Answer: Stacks of RBCs seen on peripheral smear that form in the presence of increased serum proteins, particularly fibrinogen and globulins.

Question: What diagnosis should be considered in a patient with methemoglobinemia on co-oximetry but who does not improve upon methylene blue administration?

Answer: Sulfhemoglobinemia.

Question: In von Willebrand disease is the patient's platelet count depressed, normal or increased?

Answer: The platelet count will be normal in von Willebrand disease.

A 9-year-old boy with known acute lymphocytic leukemia (ALL) presents with complaints of fatigue, frequent muscle cramps, and decreased urine production 48 hours after starting chemotherapy. Labs reveal potassium 5.5, uric acid 10.5, phosphate 4.6, and total calcium 6.2. Which of the following immediate interventions is the most important for correcting this patient's electrolyte abnormalities? Aggressive intravenous hydration Alkalinization of the urine Furosemide or mannitol for osmotic diuresis Initiation of allopurinol

Correct Answer ( A ) Explanation: This patient has tumor lysis syndrome, which results from the death of numerous neoplastic cells that release large quantities of intracellular content and uric acid in the blood stream. Electrolyte derangements include hyperuricemia (DNA breakdown), hyperkalemia (cytosol breakdown), hyperphosphatemia (protein breakdown), and hypocalcemia (secondary to hyperphosphatemia). Acute tumor lysis syndrome typically occurs 1-5 days after chemotherapy for a hematologic malignancy such as leukemia and lymphoma, particularly Burkitt's lymphoma. The integrity of renal function is a critical factor because the kidney provides the primary mechanism for excretion of uric acid, potassium, and phosphate. Therefore, the most important intervention is intravenous hydration. Tumor lysis syndrome is more likely to develop in patients with underlying renal insufficiency. Clinically, patients may present with fatigue, lethargy, nausea, vomiting, cloudy urine, muscle spasm, and altered mental status. Patients are at increased risk for developing acute renal failure and cardiac dysrhythmias. After intravenous hydration is initiated, more specific treatments should be started. Alkalinization of the urine (B), along with initiation of allopurinol (D), is important for reducing the urate burden on the kidney. Many patients are administered allopurinol prophylactically during treatment of high-growth malignancies. Diuretics (C) are reserved for well-hydrated patients with insufficient diuresis because diuretics can contribute to precipitation of uric acid or calcium phosphate crystals within the renal tubules.

A 23-year-old man with sickle cell disease presents with chest pain, cough, and fever. His vitals are HR 132, RR 28, BP 110/65, and T 101.1°F. His chest X-ray shows a right lower lobe infiltrate. Hemoglobin is 8 g/dL. Which of the following is the first line management that is most likely indicated? Broad spectrum antibiotics and ICU admission Exchange transfusion Oral antibiotics and follow up with hematology Splenectomy and broad-spectrum antiobitics

Correct Answer ( A ) Explanation: This patient with sickle cell disease (SCD) presents with acute chest syndrome requiring broad-spectrum antibiotics and intensive care unit (ICU) admission. SCD is a genetically determined disease due to an abnormal allele for hemoglobin beta chains. The end result of this abnormality is a sickled cell that is less deformable and can cause increased viscosity and sludging of the blood. Additionally, cells are sequestered in the spleen and the liver leading to destruction. Patients experience chronic hemolysis, vaso-occlusive events, thrombosis and ultimately, end organ injury. Splenic autoinfarction occurs early in life and makes patients more susceptible to encapsulated organisms such as Streptococcus pneumoniae, Haemophilus influenzae and Neisseria meningitides. Acute chest syndrome is the leading cause of death in SCD and is defined as fever, chest pain, and the presence of new pulmonary infiltrates. Management consists of supportive care, supplemental oxygen if needed, broad spectrum antibiotics, and admission to the ICU. Exchange transfusion (B) may be required in the treatment of stroke, refractory priapism and severe acute chest syndrome but is not first line therapy. These patients are too sick to be treated with oral antibiotics (C) and require close monitoring for decompensation. Splenectomy (D) is not necessary in SCD as they have likely already autoinfarcted their spleen by adulthood. Splenectomy is one of the treatments for ß-Thalasemia major.

Which of the following hematological disorders is characterized by intermittent venous and arterial thrombosis, splenomegaly, and abnormal proliferation of all three myeloid cell lines? Aplastic anemia Chronic myelogenous leukemia Disseminated intravascular coagulopathy Polycythemia vera

Correct Answer ( D ) Explanation: Polycythemia vera (PV) is a chronic myeloproliferative disorder in which vascular thromboses and splenomegaly occur secondary to an increased red blood cell mass, although abnormal proliferation is seen in all three cell lines. It should be suspected in a patient with any combination of the following: abnormally elevated hemoglobin levels (> 16.5 g/dL in men; 16 g/dL in women), normal oxygen saturation, bleeding complications, portal vein thrombosis, splenomegaly, plethora, or pruritus after bathing. Treatment is accomplished through use of myelosuppressive agents. Aplastic anemia (A) is characterized by anemia, leukopenia, and thrombocytopenia secondary to bone marrow failure. Although splenomegaly is the most common physical exam finding in patients suffering from chronic myelogenous leukemia (B), hematological cell proliferation primarily affects leukocytes, with levels ranging from 20,000-60,000 cells/µL. Disseminated intravascular coagulopathy (C) is a consumptive coagulopathy resulting in thrombocytopenia, widespread thrombosis, and abnormal bleeding.

Question: What is the immediate ED management of a patient with polycythemia vera and altered mental status?

Answer: Phlebotomy of at least 500 mL of blood.

Question: Name 4 other inherited hypercoagulable disorders?

Answer: Prothrombin mutation, hyperhomocysteinemia, and protein C and S deficiencies.

Question: What is the treatment of methemoglobinemia?

Answer: Methylene blue.

Question: Because TTP causes thrombocytopenia, should platelets be administered?

Answer: No. Platelet transfusions have been shown to cause more thromboses.

Question: What is the most common skeletal abnormality found in multiple myeloma?

Answer: Osteoporosis.

Question: Which coagulation profile is abnormal in patients with hemophilia A?

Answer: PTT.

Question: Which populations are G6PD most common in?

Answer: People of African, Asian, and Mediterranean descent.

One Step Further Question: What is the most common sign of ITP?

Answer: Petechiae.

Question: In patients with thrombocytopenia, what is the transfusion trigger in the absence of acute bleeding or required surgery?

Answer: A platelet level <10,000 should prompt transfusion as these patients are at increased risk of spontaneous hemorrhage.

Question: What is the calculation for absolute neutrophil count (ANC)?

Answer: ANC = (total WBC) x (percentage of neutrophils and bands) x 10.

Question: What medication can be used in hyperuricemia to decrease production of uric acid?

Answer: Allopurinol.

Question: What medications are most likely to cause neutropenia in adults?

Answer: Macrolides, antithyroid medications (such as methimazole), and procainamide.

Question: What is the prognosis for polycythemia vera?

Answer: Median survival from treatment to death is 9-14 years.

Question: What is the most common gram-negative pathogen identified in neutropenic fever?

Answer: Pseudomonas aeruginosa.

Question: What is characteristically seen on the peripheral blood smear in DIC?

Answer: Schistocytes.

Question: What medication, commonly used in patients with sickle cell disease, is associated with megaloblastic anemia?

Answer: Hydroxyurea

Question: What is the most common cause of immediate transfusion reactions?

Answer: Febrile transfusion reactions, usually presenting with fever, chills, and malaise.

Question: What finding on peripheral blood smear is characteristic of G6PD deficiency?

Answer: Heinz bodies, which are clumps of denatured hemoglobin.

Question: What is the name of Factor IX deficiency?

Answer: Hemophilia B or Christmas Disease.

Question: Peptic ulcer disease and pruritus are common complications of PV due to the hypersecretion of which gastric hormone?

Answer: Histamine.

Question: What is splenic sequestration crisis?

Answer: A condition seen in children with sickle cell disease when there is rapid sequestration of RBCs in the spleen causing splenomegaly and severe anemia.

Question: What other drugs can be used to stop minor mucosal bleeding in mild hemophilia A?

Answer: Aminocaproic acid or tranexamic acid.

Question: What symptoms are more likely to be seen in adults with parvovirus B19 infection than in children?

Answer: Arthralgias and arthritis.

Question: What topical anesthetic may precipitate methemoglobinemia?

Answer: Benzocaine (found in "hurricane spray").

Question: What abnormalities will be seen with hemoglobin and reticulocyte count in aplastic crisis?

Answer: Both hemoglobin and reticulocyte count will be depressed.

Question: What antibiotic is best known for causing aplastic anemia?

Answer: Chloramphenicol.

22-year-old man with severe hemophilia A presents to the ED with a superficial 3-cm laceration to his left forearm from a kitchen knife that he sustained 15 minutes prior to arrival. The wound is oozing dark blood, slowly but continuously. In addition to laceration repair and direct pressure, what is the next best step in the management of this patient? Desmopressin, intranasally Desmopressin, intravenously Recombinant factor VIII, intravenously Thrombin, topically

Correct Answer ( D ) Explanation: Topical thrombin works by aiding in the conversion of fibrinogen to fibrin, providing a hemostatic scaffold for platelet aggregation. Patients with hemophilia A (even those with severe disease classified as having < 1% factor activity levels) do not necessarily need factor replacement for abrasions and superficial lacerations where bleeding is due to superficial venule injury. Wound care, direct pressure, and topical thrombin are the mainstays of care for these patients. Deeper lacerations, such as those involving muscle compartments, will need factor VIII replacement. Desmopressin (A and B) works by promoting the release of von Willebrand factor (vWF), with a subsequent rise in complex factor VIII. This can be used for minor mucosal or superficial bleeding in patients with mild hemophilia A. This does not work in severe hemophilia A when there is little or no factor VIII present in any form. Factor VIII replacement (C) is not required for superficial lacerations and abrasions.

Question: What are the risk factors for developing torsade de pointes?

Answer: Bradycardia, hypokalemia, hypomagnesemia, congenital long QT syndrome, and concomitant use of other drugs that cause QT prolongation.

Question: What is the most common cause of vitamin B12 deficiency?

Answer: Chronic malabsorption, as seen in pernicious anemia.

Question: What virus is most commonly associated with Burkitt lymphoma?

Answer: Epstein-Barr virus.

A 43-year-old woman with breast cancer on chemotherapy presents with a fever to 102°F. She also complains of a cough and generalized fatigue. Physical examination and chest X-ray are unremarkable except for the presence of a mediport. Complete blood count reveals a white blood count of 600/mm3 with 30% neutrophils and no band forms. What management is indicated? Administer filgrastim and discharge home Draw blood cultures and await results for treatment Send blood and urine cultures and start vancomycin and cefepime Start levofloxacin and admit for pneumonia

Correct Answer ( C ) Explanation: This patient presents with neutropenic fever and requires culture of typical infectious sources and broad-spectrum antibiotics. Fever can be caused by a number of etiologies in cancer patients including inflammation, medications, antimicrobials, transfusions and tumor necrosis. Most fevers occurring in cancer patients are infectious in origin (55-70%). Neutropenia is defined as an absolute neutrophil count (ANC) < 500 cells/mm3 (or <1000 cells mm3 with predicted decline to < 500 cells/mm3) and is calculated by multiplying the total WBC count by the percentage of neutrophils and bands. Neutropenic fever is an oncologic emergency and is defined by neutropenia along with a single oral temperature >101°F or a temperature of 100.4°F for at least 1 hour. All of these patients should be managed presuming that they have a serious bacterial infection regardless of the presentation. A thorough physical examination should be performed looking for an infectious source but spontaneous bacteremia is common. Common sites include urine, chest, skin and blood and cultures should be obtained. Patients with chronic indwelling catheters should have a culture sent from this site. Broad-spectrum antibiotics covering the most likely pathogens should be started. An antipseudomonal penicillin with an aminoglycoside or a fourth generation cephalosporin are commonly started. Vancomycin should be added in patients with possible methicillin resistant Staphylococcus aureus (MRSA). This includes patients with recent hospitalizations and indwelling catheters or severe illness. Untreated neutropenic fever has a high mortality rate (~ 20%). Filgrastim (A) is used by oncologists to boost the white blood cell count in patients undergoing chemotherapy but has a delayed onset of action and will not treat a serious bacterial infection. All patients with neutropenic fever should have antibiotics started and waiting for culture results (B) delays care. Although the patient has symptoms concerning for pneumonia, levofloxacin (D) is not broad enough to cover the likely pathogens that may be present in neutropenic fever.

A 28-year-old man presents with a one-day history of rectal bleeding. In the ED, he is hypotensive, thrombocytopenic, and is found to be passing melena. He receives a transfusion of platelets and packed red blood cells as part of his resuscitation. Twenty minutes after the start of his platelet transfusion, his BP is 90 mm Hg systolic, he becomes dyspneic, and his oxygen saturation drops from 99% on room air to 91% on 2L of oxygen supplementation. On exam, you note rales at the lung apices and that he is using accessory muscles to breathe. His chest radiograph shows diffuse interstitial infiltrates. What is the most likely cause of this complication? ABO incompatibility Allergic transfusion reaction Transfusion-associated circulatory overload Transfusion-related acute lung injury

Correct Answer ( D ) Explanation: This patient is most likely suffering from transfusion-related acute lung injury (TRALI), one of the leading causes of transfusion-related mortality. It is most closely associated with platelet and fresh frozen plasma transfusions, though cases have been reported with packed red blood cells since there is some residual plasma in the packed cells. Symptoms begin abruptly during transfusion or within six hours and resemble adult respiratory distress syndrome with noncardiogenic pulmonary edema, dyspnea, hypoxemia, and bilateral infiltrates on chest radiograph. It is thought to be caused by granulocyte recruitment and degranulation. As with all severe (other than mild allergic reaction) transfusion-associated complications, the transfusion should be stopped immediately and supportive care instituted. Most cases resolve spontaneously. ABO incompatibility (A) causes intravascular hemolysis of transfused red blood cells, producing hemoglobinemia and hemoglobinuria. The onset is immediate. Symptoms include fever, chills, headache, nausea, vomiting, a sensation of chest restriction, and severe joint pain. ABO incompatibility is most often due to human error. An allergic transfusion reaction (B) can vary in severity from simple pruritus with urticaria to anaphylaxis with wheezing and bronchospasm. This patient's respiratory symptoms are not bronchospastic in nature. Although TRALI can be confused with acute transfusion-associated circulatory overload (TACO) (C), TRALI is associated with hypotension, whereas TACO is associated with a rapid rise in blood pressure.

One Step Further Question: What other laboratory finding is commonly seen with tumor lysis syndrome?

Answer: Hyperuricemia.

Question: What is the oral chelation medication for lead poisoning?

Answer: Succimer.

Question: What is the treatment for bleeding in von Willebrand disease?

Answer: Desmopressin (DDAVP), which stimulates the release of von Willebrand factor (and Factor VIII) stored in vascular endothelial cells.

Question: What tapeworm infection is associated with vitamin B12 deficiency?

Answer: Diphyllobathrium latum infection causes vitamin B12 malabsorption.

Question: What factor deficiency is the cause of hemophilia B?

Answer: Factor IX, also known as Christmas disease.

Question: What components are contained in cryoprecipitate?

Answer: Factor VIII, XIII, von Willebrand factor (vWF), fibrinogen and fibronectin.

Question: What is the most common blood transfusion reaction?

Answer: Febrile transfusion reaction characterized by fever, chills, and malaise. Treatment is symptomatic.

Question: What is the most common type of transfusion reaction?

Answer: Febrile transfusion reaction.

Question: What is the most common metabolic cause of renal insufficiency in acute tumor lysis syndrome?

Answer: Hyperuricemia with resultant urate nephropathy.

One Step Further Question: What happens to the PT(INR)/PTT in patients with idiopathic thrombocytopenic purpura?

Answer: It remains normal.

Question: What are other causes of acquired sideroblastic anemia aside from lead toxicity?

Answer: Pyridoxine deficiency, drug toxicity (chloramphenicol, isoniazid), carcinoma, leukemia, chronic alcoholism and infection.

Question: What is the most common organism causing osteomyelitis in sickle-cell patients?

Answer: Salmonellae are the most common bacterial pathogens of osteomyelitis in major sickling haemoglobinopathies in the USA and Europe whereas Staphylococcus aureus is the most common pathogen in SubSaharan Africa and the Middle East.

Which of the following is most consistent with a complication that most commonly occurs 6 to 12 weeks after acute hepatitis? WBC decreased, RBC decreased, platelets decreased WBC decreased, RBC increased, platelets increased WBC increased, RBC decreased, platelets decreased WBC increased, RBC increased, platelets increased

Correct Answer ( A ) Explanation: Aplastic anemia is a known complication of acute hepatitis. This affects up to 2% of all patients after their initial illness. Hepatitis-associated aplastic anemia most often affects adolescent boys and young men, is most commonly seen 6-12 weeks after hepatitis, and can be fatal if untreated. Its etiology is unclear. There is no known association with blood transfusions, drugs, or toxins. Most patients have been seronegative for hepatitis A, B, and C, but it is believed to be the result of autoimmune bone marrow failure. Lab findings show a decrease in the WBC, RBC, and platelet counts. Although one might expect the WBC co

What class of drugs is the most common cause of drug-induced neutropenia in children? Antibiotics Antiepileptics Antihypertensives Antipsychotics

Correct Answer ( A ) Explanation: Drug-induced neutropenia in children is an uncommon, but serious, event. It is most commonly due to exposure to antibiotics, typically macrolides, cephalosporins, and penicillins. Recognition of the phenomenon and cessation of the offending medication is vital to avoiding more serious sequelae. Presentations often include skin manifestations such as ulcers and abscesses, poor wound healing, or other infections such as pneumonia or UTI. Neutropenia results when the drug acts as a hapten, causing antibody formation and subsequent destruction of granulocytes. It appears to be dose- and duration-related in its severity. Antiepileptics (B) such as carbamazepine, ethosuximide, and phenytoin have been associated with drug-induced neutropenia, although less commonly. Hydralazine, an antihypertensive (C), has also been linked to neutropenia, but its use in children is rare. A number of antipsychotics (D), including the phenothiazines and clozapine, have been connected with neutropenia, but this occurs less frequently than with antibiotics. Clozapine is well known for causing agranulocytosis, a severe form of neutropenia.

You diagnose a 43-year-old male with alcohol withdrawal. Lab studies reveal a hemoglobin of 12 g/dL and an MCV of 115. Which of the following is the most likely cause of these findings? Direct ethanol toxicity Pyridoxine deficiency Thiamine deficiency Vitamin B12 deficiency

Correct Answer ( A ) Explanation: Ethanol affects practically every organ system in the body. This patient is suffering from macrocytic anemia, most likely as a result of chronic alcohol abuse. Chronic ethanol intake directly suppresses bone marrow by impairing protein synthesis, causing anemia or even pancytopenia. Although patients who abuse alcohol often have concomitant nutritional deficiencies that contribute to the development of megaloblastic anemia, the most likely cause of macrocytic anemia is due to direct ethanol toxicity. Macrocytosis is present in the majority of alcoholics even before significant anemia appears. This is typically reversed after several months of abstinence from alcohol. In addition to the harmful effects of ethanol itself, its metabolite, acetaldehyde, is inherently toxic to biologic systems. Patients presenting with acute ethanol intoxication also commonly have decreased serum ionized magnesium concentrations. Total body magnesium may be depleted due to poor dietary intake, decreased GI absorption, and renal wasting. Pyridoxine deficiency (B) (vitamin B6) is a pediatric disease which usually becomes noticeable within the first 12 months of life in infants with lack of pyridoxine, a coenzyme responsible for numerous essential metabolic reactions. The disease presents with several key symptoms including seizures, irritability, cheilits (inflammation of the lips), conjunctivitis, and neurologic symptoms. In patients receiving isoniazid, pyridoxine deficiency can lead to a sideroblastic anemia because it is required as a cofactor in heme synthesis. Pyridoxine deficiency is a cause of microcytic anemia not macrocytic anemia. Thiamine (C) (vitamin B1), is a water-soluble vitamin not stored in the body to any significant extent, and is therefore subject to deficiencies in patients with poor diet, including alcoholics, pregnant women suffering from hyperemesis gravidarum, and patients with anorexia nervosa. Deficiencies in thiamine result in neurologic consequences such as Wernicke's encephalopathy. It is not associated with macrocytic anemia. Vitamin B12 (D), or cyanocobalamin, is a water-soluble vitamin. Dietary deficiencies can cause megaloblastic anemia, pancytopenia, and neuropsychiatric symptoms. Because of the size of the B12 molecule, deficiencies typically result from issues with absorption (such as pernicious anemia), rather than from poor dietary intake.

In a malnourished patient, which of the following sources of megaloblastic anemia is expected to develop first? AFolic acid deficiencyCorrect Answer BHypothyroidism CLiver disease DVitamin B12 deficiency

Correct Answer ( A ) Explanation: Even though all the answer choices are causes of macrocytic anemia, only folic acid deficiency and vitamin B12 deficiency are sources of megaloblastic anemia. Megaloblastic changes include large oval red cells and hypersegmented neutrophils on peripheral blood smear. Folic acid is found in green vegetables, cereals, and fruits and is destroyed by cooking. Typically, the body has a 2-4-month supply of folic acid available before megaloblastic changes occur. Vitamin B12 (D) is found in foods of animal origin and is not destroyed by cooking. The body maintains enough Vitamin B12 to last up to 4 years prior to the development of megaloblastic changes. Megaloblastic anemia can be treated with folic acid and vitamin B12 replacement. Macrocytic anemia not associated with megaloblastic anemia includes liver disease (C) and hypothyroidism (B). Frequently, macrocytic anemia is seen in alcoholic patients with liver disease, along with target cells on the peripheral smear. Hypothyroidism is also associated with macrocytic anemia.

What is the most common location for spontaneous bleeding in children with hemophilia A? Ankle Elbow Gastrointestinal tract Knee

Correct Answer ( A ) Explanation: Hemophilia A is an X-linked recessive disease that includes a range of clinical manifestations characterized by the activity of factor VIII. Severe hemophilia is characterized by spontaneous hemarthrosis. It differs from platelet disorders, such as von Willebrand disease that manifest as mucosal bleeding (epistaxis, gingival bleeding) and bullous hemorrhage of buccal mucosa. In patients with mild (>5% factor VIII activity) and moderate hemophilia (1%-4% factor VIII activity), usually an insult causes bleeding, whereas spontaneous bleeding is more common in severe disease (<1% factor VIII activity). Spontaneous intracranial hemorrhage can occur in all ages but is more common in neonates. Patients with hemophilia seldom bleed from small cuts or venipuncture, but they do hemorrhage out of proportion to larger injuries. Delayed bleeding is also common. Although bleeding may occur in any area of the body, the most common sites include joints, muscles, and the GI tract. However, 80% of hemorrhage occurs in the joints. In children, the most common joint is the ankle. In adults, the most common joint is the knee, followed by the elbow and ankle. The elbow (B), gastrointestinal tract (C), and knee (D) are all locations for spontaneous bleeding in children with hemophilia A but less common than the ankle is.

41-year-old previously healthy woman presents to the ED with gingival bleeding and epistaxis over the past 4 days. She takes no medications and has no recent travel. On exam, you note scattered petechiae, but otherwise it is normal. Her hemoglobin is 12.5 g/dL, INR 1.1, PTT 25, and platelets 14,000/µL. A peripheral blood smear shows few large, well-granulated platelets. Which of the following is the most appropriate initial treatment? Corticosteroids and immunoglobulin Observation Platelet transfusion Splenectomy

Correct Answer ( A ) Explanation: Idiopathic thrombocytopenic purpura (ITP) is an acquired autoimmune disease that results in rapid destruction of platelets. It is characterized by thrombocytopenia, the presence of purpura or petechiae, normal bone marrow, and no other identifiable cause for the thrombocytopenia. It is more common in children than in adults. The physical exam may reveal petechiae, epistaxis, gingival bleeding, and menorrhagia. The presence of lymphadenopathy, hepatosplenomegaly, pallor, or hyperbilirubinemia should suggest an alternative diagnosis such as leukemia, lymphoma, lupus, mono, or hemolytic anemia. Management is predicated primarily on the severity of thrombocytopenia and bleeding. Drugs that interfere with platelet function are discontinued. In general, asymptomatic patients with platelet counts >50,000/µL require no treatment. Prednisone is the initial therapy for adult patients with platelets < 50,000/µL who are not actively bleeding but have other signs (ecchymoses, petechiae, etc). When the platelet count is < 20,000/µL, IV methylprednisolone is preferred. Intravenous (IV) immunoglobulin is co-administered for patients with counts < 20,000-30,000/µL and active bleeding.

Which of the following antibiotics is most appropriate to use in a 64-year-old man with a history of benign prostatic hyperplasia and glucose-6-phosphate dehydrogenase deficiency and a recently diagnosed urinary tract infection? Cephalexin Nitrofurantoin Phenazopyridine Trimethoprim-sulfamethoxazole

Correct Answer ( A ) Explanation: In this patient with benign prostatic hypertrophy (BPH), glucose-6-phosphate dehydrogenase (G6PD) deficiency, and cystitis, care must be taken not to precipitate a hemolytic crisis. Oxidant drugs such as nitrofurantoin, phenazopyridine, dapsone, and sulfonamides can cause hemoglobin precipitation within the RBC, which leads to removal of the cell from circulation via the spleen. Patients with severe G6PD enzyme deficiency who ingest oxidant drugs can experience severe hemolysis and cardiovascular collapse. For those with more minor forms of the hereditary disease, the lengthy course of antibiotics required for this complex cystitis may be sufficient to cause symptomatic hemolytic anemia, jaundice, and splenomegaly. Cephalexin, a first-generation cephalosporin, is not associated with causing oxidative stress and is, therefore, an acceptable choice for this patient.

Which of the following medications can induce methemoglobinemia? Benzocaine Ciprofloxacin Isoniazid Phenytoin

Correct Answer ( A ) Explanation: Methemoglobinemia occurs when the iron atom in hemoglobin loses 1 electron to an oxidant, and the ferrous (Fe2+) state of iron is transformed into the ferric (Fe3+) state. When the body's ability is overwhelmed by an oxidant stress, the result is an impaired oxygen-carrying capacity and delivery to the tissue. Cyanosis is a consistent physical finding in patients with substantial methemoglobinemia due to the deeply pigmented color of methemoglobin. At 20%-50% methemoglobin levels, dizziness, fatigue, headache, and exertional dyspnea may develop. At approximately 50% methemoglobin, lethargy and stupor usually appear. On lab analysis, methemoglobinemia has characteristic findings. The PaO2 concentration is normal; however, the measured oxygen saturation (pulse oximetry) is low because methemoglobin absorbs light at wavelengths that also absorb deoxyhemoglobin and oxyhemoglobin. Thus methemoglobin interferes with the colorimetric testing used to obtain the percentage of oxyhemoglobin to deoxyhemoglobin. Therefore, any patient who is cyanotic but relatively asymptomatic with a low O2 saturation reading (around 85%) should raise suspicion for methemoglobinemia. Topical anesthetics, such as Cetacaine spray (14% benzocaine, 2% tetracaine, 2% butyl aminobenzoate) and Hurricaine spray (20% benzocaine) are the agents most commonly associated with production of methemoglobin.

What is the best approach to treat a hemodynamically stable patient that begins to complain of hives and pruritus shortly after starting a blood transfusion? Continue the transfusion and administer an antihistamine Stop the transfusion and begin diuretic therapy Stop the transfusion, notify the blood bank, and assess respiratory status Treat with epinephrine and corticosteroids, resume transfusion with washed RBCs

Correct Answer ( A ) Explanation: The patient is experiencing an allergic reaction manifested by pruritic urticaria without other serious signs or symptoms. The reaction is likely due to an antibody-mediated response to the donor's plasma. The transfusion does not need to be stopped for such a reaction; an intravenous antihistamine will help to relieve symptoms. Although rare, anaphylaxis can occur in the setting of IgA deficiency. Patients with IgA deficiency have sensitized anti-IgA antibodies, which can react with the donor's IgA. In the case of anaphylaxis, the transfusion should be stopped, and the patient should be treated with epinephrine and corticosteroids (D). Future transfusions should be with washed RBCs. Transfusion-related acute lung injury (TRALI) presents as noncardiogenic pulmonary edema, with rapid onset of dyspnea, hypoxia, and bilateral infiltrates on chest X-ray. It is the leading cause of transfusion-related mortality and should be treated by stopping the transfusion, notifying the blood bank, and supporting respiratory status with mechanical ventilation if needed (C). Elderly patients are most at risk for circulatory overload (B), particularly when the transfusion is given rapidly. Administering a single unit over 4 hours and giving diuretics can alleviate this risk.

What is the most likely cause of acute anemia in an African-American patient with HIV infection who recently began pneumocystis pneumonia prophylaxis? Glucose-6-phosphate-dehydrogenase (G6PD) deficiency Hereditary spherocytosis Paroxysmal nocturnal hemoglobinuria Pyruvate kinase deficiency

Correct Answer ( A ) Explanation: The patient most likely has hemolytic anemia caused by oxidative stress in the setting of G6PD deficiency. Pneumocystis pneumonia prophylaxis is most commonly initiated with trimethoprim/sulfamethoxazole, an agent known to be associated with hemolysis in patients with G6PD deficiency. Up to 85% of the energy generated by RBCs to sustain membrane stabilization occurs via anaerobic glycolysis. At least eight known enzymatic deficiencies are found in the glycolytic pathway, including pyruvate kinase deficiency, a cause of hemolytic jaundice, usually diagnosed in infants. The other 15% of energy comes from the production of nicotinamide adenine dinucleotide phosphate (NADPH) via the hexose monophosphate shunt pathway. NADPH is necessary for the reduction of oxidized glutathione, an antioxidant that contributes significantly to membrane stabilization. The first enzyme in the hexose monophosphate pathway is G6PD. Without G6PD, the RBC membrane is subject to hemolysis when exposed to oxidative stressing agents, including aspirin, antimalarials, nitrofurantoin, sulfa drugs, fava beans, and methylene blue. G6PD deficiency is diagnosed by enzymatic screening. Hereditary spherocytosis (B) is a congenital intrinsic membrane abnormality in which RBCs are shaped like spheres. Clinical sequelae can range from compensated hemolysis to aplastic crisis. Diagnosis is made via blood smear and osmotic fragility testing. Splenectomy is the definitive treatment. Paroxysmal nocturnal hemoglobinuria (PNH) (C) is a stem cell defect in which there is an abnormal sensitivity to complement-mediated destruction of RBCs. This destructive process is a result of a defect in the formation of surface proteins on the red blood cell, which normally functions to inhibit immune reactions. For this reason, blood transfusion can be fatal, and only washed blood cells should be given to patients with PNH. Pyruvate kinase deficiency (D) is a cause of hemolytic jaundice, usually diagnosed in infants.

A 3-year-old girl with a past medical history of constipation is brought to the ED for evaluation of a limp and left knee pain. Her physical exam is unremarkable. You obtain the knee radiograph seen above. What do you expect to see on her peripheral blood smear? Basophilic stippling Heinz bodies Hypersegmented neutrophils Schistocytes

Correct Answer ( A ) Explanation: This patient has lead lines on her knee radiograph, a classic finding of lead poisoning. These hyperdense lines occur at the metaphyses and are most commonly seen in young children on knee and wrist radiographs. Similar lines may also be seen in other heavy metal poisoning such as bismuth and arsenic, and in healing rickets or scurvy. Lead poisoning causes a microcytic, hypochromic anemia. On peripheral blood smear, the pathognomonic finding is basophilic stippling. Basophilic stippling represents clumps of degraded RNA that have not been eliminated due to lead-induced nucleotidase inhibition. This child's joint pain and constipation are likely related to lead poisoning. Heinz bodies (B) are inclusions within red blood cells made of denatured hemoglobin. They are seen in glucose-6-phosphate deficiency, liver disease, and alpha-thalassemia. Hypersegmented neutrophils (C) are seen in multiple forms of megaloblastic anemia such as that caused by alcohol abuse, folate deficiency, and vitamin B12 deficiency. Schistocytes (D) are fragmented red blood cells caused by shearing with fibrin strands in microarterioles. They are seen on smears in patients with artificial heart valves and in numerous disease processes, including hemolytic uremic syndrome, thrombotic thrombocytopenic purpura, disseminated intravascular coagulation, and congestive heart failure

Which of the following labs are most consistent with a toxic-appearing patient with known sickle cell disease who was exposed to a child with a recent febrile illness characterized by the rash seen above? Reticulocyte count decreased, Coombs negative, haptoglobin normal Reticulocyte count decreased, Coombs positive, haptoglobin decreased Reticulocyte count increased, Coombs negative, haptoglobin decreased Reticulocyte count increased, Coombs positive, haptoglobin normal

Correct Answer ( A ) Explanation: This patient is suffering from an aplastic crisis. In patients with sickle cell disease (SCD), certain viruses, parvovirus B19 being the best known, are cytotoxic to host cells and can cause suppression of erythrogenesis and subsequent aplastic crisis. Although all cell lines are typically affected, the severe anemia has the greatest clinical impact because these patients are chronically anemic due to sickle cell disease. Clinically, patients develop pallor, lethargy, and shock. The bone marrow suppression leads to an absence of reticulocytosis, so an inappropriately low (or nonexistent) reticulocyte count is seen. The Coombs test detects immunoglobulins or complement on the surface of red blood cells in autoimmune hemolytic anemia. Therefore, this patient will be Coombs negative. Haptoglobin binds to free hemoglobin in hemolytic anemia. Because this patient is experiencing marrow suppression, rather than a hemolytic crisis, the haptoglobin is expected to be normal. Coombs will be negative (B, D), not positive because this is not due to an autoimmune etiology. Reticulocytes will be decreased (C), not increased due to marrow suppression. Although a splenic sequestration crisis can present similarly, it is almost exclusively seen in children and would cause splenomegaly on exam.

A 24-year-old man presents short of breath. He reports inhaling amyl nitrite. His oxygen saturation is 85% on room air and he is cyanotic. Which of the following is the best treatment of this condition? Methylene blue Pralidoxime Sodium nitrite Sodium thiosulfate

Correct Answer ( A ) Explanation: This patient is suffering from methemoglobinemia, induced by inhalation of amyl nitrite. An iron atom in the hemoglobin loses an electron causing iron to move from the ferrous (Fe2+) state to the ferric (Fe3+) state. Methemoglobin shifts the oxyhemoglobin dissociation curve and impairs the ability of hemoglobin to deliver oxygen to the tissue. Patients become cyanotic due to impaired oxygen delivery. Oxygen saturation usually hovers around 85% and this does not improve with supplemental oxygen. Co-oximetry, if available, can confirm methemoglobin. If the diagnosis is not made from history, an arterial blood gas will identify a normal PaO2 despite cyanosis. When blood is drawn, it appears chocolate brown in color. The antidote for methemoglobinemia is methylene blue administered intravenously. This accelerates the reduction of methemoglobin back to the ferrous state allowing for normal oxygen delivery. Pralidoxime (B) is the antidote for organophosphate poisoning. Organophosphates bind to the cholinesterase enzyme preventing the breakdown of acetylcholine at the muscarinic and nicotinic receptors. Pralidoxime (2-PAM) binds to the organophosphate attached to the cholinesterase enzyme causing it to be released and regain activity in the breakdown of acetylcholine. Sodium thiosulfate (D) and sodium nitrite (C) are both components of the treatment for cyanide toxicity. Sodium thiosulfate enhances the conversion of cyanide to thiocyanate which is renally excreted. Sodium nitrite induces the formation of methemoglobin which can combine with cyanide and prevents its poisoning of the cytochrome oxidase enzyme

A 43-year-old man with a history of alcoholism presents with generalized weakness. Physical examination reveals pale conjunctiva. The patient's hematocrit is 25% and his mean corpuscular volume is 110 fL. Which of the following treatments is most likely indicated? Folic acid supplementation Lead chelation therapy Splenectomy Thiamine supplementation

Correct Answer ( A ) Explanation: This patient presents with megaloblastic anemia likely due to folic acid deficiency secondary to alcohol abuse. Megaloblastic anemia is defined as anemia in the presence of macrocytic red blood cells. It is an important cause of reversible anemia. Megaloblastic anemia is the manifestation of defective DNA synthesis in response to a lack of vitamin B12 and folic acid. Rapid hematopoietic cell turnover leads to ineffective erythropoiesis and pancytopenia. Differentiating folic acid deficiency from vitamin B12 deficiency requires serum testing. Folic acid deficiency is common in those with inadequate dietary intake from chronic alcohol use and increased use, as in pregnancy. B12 deficiency, on the other hand, usually results from chronic malabsorption. Supplementation with 1 mg of folic acid every day can lead to resolution of this disorder. Lead chelation therapy (B) is indicated for lead toxicity causing a microcytic anemia, not macrocytic. Basophilic stippling is commonly seen in lead toxicity as well. Splenectomy (C) can be therapeutic in the management of Thalassemias. Thiamine (D) (vitamin B1) is often deficient in chronic alcoholics as well but does not cause anemia. Thiamine is required in glucose metabolism and can result in Beriberi or Wernicke-Korsakoff syndrome.

Which of the following lab results is consistent with disseminated intravascular coagulation? Decreased platelets, elevated fibrinogen levels Decreased platelets, low fibrinogen levels Increased platelets, elevated fibrinogen levels Increased platelets, low fibrinogen levels

Correct Answer ( B ) Explanation: Disseminated intravascular coagulation (DIC) is a disorder of inappropriate and diffuse activation of the coagulation and fibrinolysis cascades, leading to a life-threatening syndrome marked by bleeding and concomitant thrombosis. It is most commonly caused by infections but can also result from trauma, burns, shock, pregnancy (classically an amniotic fluid embolism), transfusion, or surgery. The most common abnormality is progressive thrombocytopenia, a phenomenon that occurs despite the fact that platelets are an acute-phase reactant and thus expected to rise in many of the disease processes associated with DIC. Platelets and fibrinogen are acute-phase reactants and would be expected to rise; however, both levels decline (A, C, and D) in DIC. This abnormality is caused by the consumptive nature of the activated fibrinolysis cascade.

A patient suffers from recurrent deep vein thromboses. Which of the following is the most likely diagnosis? Alpha thalassemia Factor V Leiden von Willebrand disease Waldenström's macroglobulinemia

Correct Answer ( B ) Explanation: Factor V Leiden is the most common inherited hypercoagulability disorder, with a prevalence of 3%-7% of Caucasians. It has an autosomal dominant inheritance pattern. Its excessive clotting occurs in veins much more than in arteries, giving rise to deep vein thrombosis and pulmonary embolism. It rarely causes stroke or myocardial infarction. Normally, factor V allows factor Xa to activate thrombin, which in turn generates the fibrin meshwork of a clot. This pathway is kept in check via the anticoagulant activity of activated protein C, which normally degrades factor V. In the disease state, a genetic mutation produces a Leiden variant of factor V that resists degradation by activated protein C, resulting in a net effect of more coagulation than anticoagulation. Alpha thalassemia (A) is a microcytic anemia due to a chromosome 16 abnormality, in which abnormal hemoglobin is produced. Clinical manifestations range from being a silent carrier to mild anemia to severe anemia. It has no association with thrombosis. von Willebrand disease (C) is the most common inherited bleeding disorder. It is not a hypercoagulable disorder. Waldenström's macroglobulinemia (D) is an antibody-over-producing neoplasm of the B-lymphocytes. In addition to fatigue, it presents with a hyperviscosity syndrome and cryoglobulinemia, which can be confused with thrombosis. The hyperviscosity symptoms of blurred vision, dizziness, congestive heart failure, and pulmonary infiltrates are not due to abnormal thrombosis. Cryoglobulinemia can lead to Raynaud's phenomenon, which causes blood flow obstruction via vasospasm, not thrombosis.

What diagnosis is suggested by a patient with perioral and mucus membrane bluish discoloration, an oxygen saturation of 85% despite a nonrebreather, and no signs of respiratory compromise? Cardiogenic shock Methemoglobinemia Pulmonary embolism Sepsis

Correct Answer ( B ) Explanation: Methemoglobinemia is a state of hemoglobin in which the iron exists in the ferric form (Fe3+), as opposed to the oxygen-binding ferrous state (Fe2+). Normally, less than 1% methemoglobinemia is present in blood, but when the methemoglobin concentration exceeds approximately 15%, cyanosis manifests. Pulse oximetry is inaccurate when measuring oxygen saturation in patients with methemoglobinemia and tends to approach 85% regardless of the actual partial pressure of oxygen or oxygen saturation. The mechanism for this phenomenon involves light absorbance at both wavelengths used by pulse oximetry for detecting the ratio between oxyhemoglobin and deoxyhemoglobin. The appearance of blood with high methemoglobin is characteristically dark brown-purple, even when exposed to air. Patients with methemoglobinemia tend to be relatively asymptomatic until the methemoglobin concentration exceeds 20%. Methemoglobinemia can be congenital, caused by either deficient levels of NADH reductase (the primary enzyme involved in the reduction of iron from its ferric state to its ferrous state) or an abnormally functioning enzyme. The disease can also be acquired, caused by a host of medications and chemical agents, including amyl nitrite, nitroprusside, nitroglycerin, local anesthetics (lidocaine, prilocaine, benzocaine), quinolones, paraquat, and well water (nitrates). The treatment involves administration of methylene blue, which enhances the reduction of methemoglobin to hemoglobin. Treatment is indicated for symptomatic patients with greater than 15% methemoglobin and for all patients with greater than 30% methemoglobin. Central cyanosis suggests a shunting of unsaturated blood from the venous to the arterial side or abnormal hemoglobin, whereas peripheral cyanosis suggests a low-flow state secondary to low cardiac output or vasoconstriction. The patient in this clinical scenario exhibits central cyanosis. Peripheral cyanosis, not central, would be expected in cardiogenic shock (A), in addition to correction of oxygen saturation with administration of oxygen via nonrebreather. A patient with a pulmonary embolism (C) large enough to cause hypoxemia would be expected to have signs or symptoms of respiratory distress. Also, a septic patient (D) would be expected to have tachypnea in the presence of hypoxemia, and oxygen saturation would be expected to improve with administration of a nonrebreather.

You obtain the radiograph seen above on a 75-year-old man with fatigue. You are also informed that he has Bence-Jones protein in his urine. What is the most likely diagnosis? Lymphoma Multiple myeloma Paget disease Prostate Cancer

Correct Answer ( B ) Explanation: The presence of lytic lesions in bone, especially in an older patient, is always concerning for malignancy. Common malignancies that metastasize to bone include breast, lung, thyroid, and kidney cancers. Multiple myeloma is the most common primary malignant neoplasm of the skeletal system. It is characterized by multiple destructive lytic lesions, as well as severe demineralization of the skeleton, as seen in the skull radiograph. It is also associated with light chains (Bence-Jones protein) in the urine. Multiple myeloma occurs most commonly in older men, age 60 to 70 years. Prostate cancer (D) is associated with bony metastases that are purely blastic (associated with enhanced osteoblast activity causing bony sclerosis on radiograph). Primary lymphoma (A) of bone is one of the least common primary skeletal malignancies. Metastatic lymphoma is associated with lytic bone lesions, typically a single large lytic lesion with a permeative destruction. It is also associated with a metadiaphyseal location and periosteal location. Paget disease (C) of the bone (osteitis deformans) is a metabolic disorder characterized by abnormal osseous remodeling. Lytic appearing skull lesions are possible, but Paget disease is not associated with Bence-Jones protein. In addition, the lytic lesion of Paget is usually much larger than the moth-eaten lesions seen with multiple myeloma.

60-year-old woman presents to the ED with a rash. She has a history of Graves' disease that was treated surgically. Her only medication is levothyroxine. She has a petechial rash on her arms and around her gum line with diffuse bruising on her legs. Her platelet count is 16,000, but the rest of her labs are within normal limits. What is the most likely etiology of this patient's thrombocytopenia? Adverse drug reaction Idiopathic thrombocytopenic purpura Splenic sequestration Thrombotic thrombocytopenic purpura

Correct Answer ( B ) Explanation: This patient has idiopathic thrombocytopenic purpura (ITP). ITP generally presents as a purpuric rash or easy bruising in an otherwise asymptomatic patient. Other cell lines are normal unless the patient has had significant bleeding, in which case the hemoglobin and hematocrit may be low. Thrombocytopenia occurs as a result of autoimmune destruction of platelets. Other symptoms, when present, include nosebleeds, bleeding gums, and hematuria. The distribution is bimodal occurring in young children after a viral illness and in older females with a history of autoimmune disease. ITP in children will spontaneously resolve, however, ITP in older individuals tends to follow a more chronic course. Bone marrow biopsy is generally normal in ITP. Treatment is based on the platelet count and the presence of bleeding. Asymptomatic individuals with a platelet count > 50,000 do not require treatment. Those with platelet counts between 20,000 and 50,000 can be treated with a prednisone taper. Patients with lower platelet counts or those with significant bleeding should be treated with IV immunoglobulin, IV steroids, and possibly anti-D antibody.

A 17-year-old boy presents to the ED with a painless mass on the left side of his neck, which he first noticed three months ago, that is now increasing in size. The patient also reports a 10-pound weight loss and night sweats. On exam, you note a 5 cm rubbery, firm, and mobile mass located in the anterior cervical triangle. The overlying skin is intact, with no redness, streaking, or drainage. What is the most likely diagnosis? Burkitt lymphoma Hodgkin's lymphoma Non-Hodgkin's lymphoma T-cell lymphoma

Correct Answer ( B ) Explanation: This patient most likely has Hodgkin's lymphoma. Lymphoma is the most common malignancy of the head and neck in children. Hodgkin's lymphoma typically occurs in teenagers, with a neck mass serving as the presenting complaint 80% of the time. The mass is most often supraclavicular or in the anterior cervical triangle. It is often accompanied by constitutional symptoms such as weight loss, fevers, and night sweats (B symptoms). Non-Hodgkin's lymphoma (C) is most common in children between two and twelve years of age; extranodal involvement as well as lymphadenopathy below the clavicles are frequently seen. Burkitt lymphoma (A) is a form of non-Hodgkin's lymphoma. It is considered the fastest growing human tumor and unlikely to grow slowly over the course of four months. Although neck masses can occur, in the United States the intra-abdominal form of the disease is most common. There are four types of T-cell lymphoma (D). Collectively, they comprise about 10% of non-Hodgkin's lymphomas and are much less likely to be the cause of this patient's illness.

A 43-year-old woman with a history of von Willebrand disease presents with epistaxis. Vital signs are normal and examination reveals oozing from the right nares despite applying pressure. Which treatment is indicated in this patient's management? Cryoprecipitate Desmopressin Factor VIII concentrate Fresh frozen plasma

Correct Answer ( B ) Explanation: This patient presenting with mild bleeding with a history of von Willebrand disease should have desmopressin (DDAVP) administered. von Willebrand disease is a common inherited bleeding disorder. von Willebrand factor (vWF) is involved in factor VIII activity in supporting platelet adhesion. Platelets have normal morphology but in the absence of factor VIII/vWF complex their ability to adhere is impaired. There are three types of von Willebrand disease: Type I - mild to moderate decrease in vWF, Type II - dysfunctional vWF, Type III - absolute lack of vWF. Patients predominantly present with mucosal surface bleeding including epistaxis and bleeding from the gums. Menorrhagia and gastrointestinal bleeding are common but hemarthrosis is rare. Diagnosis is classically made with an abnormal bleeding time. A reduction in vWF activity will also be seen. In patients with mild mucosal bleeding, desmopressin or DDAVP is sufficient for treatment. Desmopressin acts by increasing circulating levels of factor VIII and vWF. It can be administered intravenously or nasally Cryoprecipitate (A) contains factor VIII, XIII, von Willebrand factor (vWF), fibrinogen and fibronectin and can be used in patients with severe bleeding. Fresh frozen plasma (D) should only be used in severe bleeding when factor VIII concentrate is not available. Factor VIII concentrate (C) is first line therapy in patients with vWF and severe bleeding if available.

A 23-year-old with acute lymphocytic leukemia (ALL) presents with generalized weakness and muscle cramps. The patient states that he started chemotherapy three days ago. A basic metabolic panel shows serum potassium 6.5 mEq/L, calcium 6.3 mg/dl and creatinine 11.1 mg/dL. What management is indicated? Aggressive fluids and admit Aggressive fluids and emergent dialysis Kayexalate and admit Urine alkalinization

Correct Answer ( B ) Explanation: This patient presents with symptoms and signs of tumor lysis syndrome (TLS) and multiple electrolyte and metabolic abnormalities requiring dialysis. TLS occurs secondary to increased cell death in a rapidly growing tumor. It frequently occurs hours to a few days after the initiation of chemotherapy or radiation therapy. TLS is commonly seen in hematologic malignancies (ALL, non-Hodgkin's lymphomas) and in some solid tumors like small-cell lung carcinoma. Patients will present with symptoms and signs that reflect their electrolyte abnormalities and can be non-specific depending on severity. With hyperkalemia, ECG changes are common and can be exacerbated by concomitant hypocalcemia. Hyperphosphatemia and hyperuricemia are also common. Kidney function is a critical factor in the development and treatment of metabolic abnormalities as it is responsible for the removal and resorption of the various electrolytes involved. Initial therapy should be with stopping chemotherapy and/or radiation and starting fluids. Further care depends on the electrolyte abnormalities present. With severe metabolic derangements, hemodialysis is required. The figure below contains the six indications for emergent hemodialysis: While aggressive fluids are required (A) they are not adequate for treatment in this patient with elevated potassium and creatinine. Kayexalate (C) may treat hyperkalemia but is delayed in onset and will not treat the other metabolic derangements. Urine alkalinization (D) is no longer indicated in tumor lysis syndrome as there was little evidence to suggest continued administration. Furthermore, alkalinization of the urine has the potential disadvantage of promoting calcium phosphate deposition in the kidney, heart, and other organs in patients with marked hyperphosphatemia.

A 27-year-old man with a history of von Willebrand's disease presents for epistaxis. Bleeding is difficult to control. Which of the following is first line treatment to help decrease bleeding? Cryoprecipitate Desmopressin Fresh frozen plasma Prothrombin complex concentrate

Correct Answer ( B ) Explanation: von Willebrand's disease is the most common hereditary bleeding disease affecting approximately 1% of the population. The mutation in the disease leads to the impaired function of or decreased levels of the factor. The von Willebrand factor (VWF) is a necessary co-factor for successful platelet aggregation. Clinical symptoms include easy bruising, skin bleeding, and prolonged bleeding from mucosal surfaces (gums, nose). In a severe variant of von Willebrand's disease, the function of Factor VIII is impaired as well since that factor requires VWF as well. Desmopressin (DDAVP) has been shown to increase levels of VWF and Factor VIII. It is a synthetic form of antidiuretic hormone and stimulates the release of VWF from endothelial cells. It can be administered intranasally, intravenously or subcutaneously. Cryoprecipitate (A) is typically administered in cases of DIC where patients have decreased levels of fibrinogen since this is present in a high concentration in cryo. It can be used in severe cases of VWD because it does contain Factor VIII. Fresh frozen plasma (C) is used to reverse the anticoagulant effects of warfarin since it contains the clotting factors whose production is inhibited by that medication. Prothrombin complex concentrate (D) is a reversal agent that contains specific clotting factors also helpful in reversing the effects of warfarin. It is available in both a three factor and four factor formulation.

A 19-year-old man with refractory schizophrenia is brought to the ED by his mother for an acute psychotic episode. Routine laboratory tests reveal a WBC count of 1.0. His mother reveals that he recently started a new medication. Which of the following medications is the patient most likely taking? Chlorpromazine Clonazepam Clozapine Levetiracetam

Correct Answer ( C ) Explanation: Clozapine is an atypical antipsychotic medication that controls both positive and negative symptoms of psychotic disorders. Clozapine causes agranulocytosis in 1%-2% of patients during the first few months of treatment. The risk of developing agranulocytosis is highest approximately three months into treatment and decreases substantially thereafter. Other potential side effects include dyslipidemia, diabetes, and decreased seizure threshold. Levetiracetam (D) is an anticonvulsant agent used in the treatment of epilepsy. Levetiracetam is well tolerated. Some serious side effects may include depression, hallucinations, and suicidal thoughts. Chlorpromazine (A) is a typical antipsychotic used in the treatment of psychosis, schizophrenia, and recurrent hiccups. Its main side effects are due to its anticholinergic properties. Clonazepam (B) is a benzodiazepine that enhances the action of GABA and causes general CNS depression. It is not associated with agranulocytosis.

A 4-year-old boy with hemophilia A presents to the ED after he fell from the monkey bars and struck his head on the ground. On exam, he has a large occipital hematoma and a GCS of 14. Which of the following should be administered? Cryoprecipitate Factor IX concentrate Factor VIII concentrate Recombinant human factor VIIa

Correct Answer ( C ) Explanation: Hemophilia A is an X-linked, recessive disorder in which there is deficiency of factor VIII:C. Severe hemophiliacs have both spontaneous and traumatic bleeding problems throughout their lives. Head trauma is potentially life-threatening to hemophiliacs. Central nervous system bleeding is the major cause of death for patients in all age groups. In the setting of potentially life-threatening bleeding, patients with hemophilia A should be assumed to have 0% activity. These patients should receive factor VIII concentrate to increase the factor VIII activity to greater than 50% and preferentially to 100%. Cryoprecipitate (A) is the cold precipitable protein fraction derived from fresh frozen plasma. It was once the mainstay of treatment for hemophilia A. Factor VIII concentrate is a more specific therapy. If factor VIII concentrate is not available, cryoprecipitate can be administered. Recombinant human factor VIIa (D) is used for hemophilia patients who have developed inhibitors against replacement coagulation factor. Factor IX replacement (B) is used for patients with hemophilia B.

What disease is suggested by an increased hemoglobin concentration, leukocytosis, and thrombocytosis? Chronic myelogenous leukemia (CML) Multiple myeloma Polycythemia vera Pulmonary disease

Correct Answer ( C ) Explanation: Polycythemia can be divided into primary (polycythemia vera) and secondary. Polycythemia vera is a myeloproliferative disease in which all cell lines are increased and hemoglobin levels are typically greater than 18.5 g/dL in men and 16.5 g/dL in women. Symptoms are generally due to sludging of blood flow leading to poor oxygen delivery. Common complaints include weakness, headache, vision changes, and bleeding. Thrombosis and hemorrhage due to ischemia secondary to thrombosis are the main causes of death in patients with polycythemia vera. Secondary causes of polycythemia include conditions that increase erythropoietin (EPO) levels such as lung disease, heart disease, high altitude, and EPO secreting tumors. Chronic myelogenous leukemia (A) is a myeloproliferative disease in which a neutrophilic leukocytosis predominates. In CML, the leukocyte alkaline phosphatase score is decreased (it is increased in polycythemia vera). Multiple myeloma (B) is a myeloproliferative disease in which plasma cells are overproduced and often crowd out other cell lines. Pulmonary disease (D) is a common cause of secondary polycythemia but would not be expected to cause an increase in all cell lines.

A 32-year-old woman, who is at 20 weeks gestational age, presents to the ED after a seizure. Her vital signs are BP 115/70, HR 105, RR 16, T 38.5°C, and pulse oximetry 98% on room air. On exam, you note some confusion, but otherwise there are no focal deficits. Lab results reveal a hemoglobin of 7 g/dL and platelets of 12,000/µL. A peripheral blood smear reveals schistocytes. Which of the following is the most appropriate treatment for her condition? Delivery of fetus Magnesium sulfate Plasmapharesis Platelet transfusion

Correct Answer ( C ) Explanation: The patient has thrombotic thrombocytopenic purpura (TTP). The classic pentad of TTP includes CNS abnormalities, renal pathology, fever, microangiopathic hemolytic anemia, and thrombocytopenia. However, diagnostic criteria have recently been simplified to include all adults with microangiopathic or microvascular hemolytic anemia and thrombocytopenia with no other explanation for these findings. TTP shares many clinical and laboratory features of HELLP syndrome. HELLP syndrome is less common before 24 weeks gestation. The derangements in hemoglobin and platelet levels are more severe in TTP. The mainstay of treatment for TTP is plasmapheresis (plasma exchange), which can achieve remission of disease in 80% of patients. If plasmapheresis cannot be immediately performed, fresh frozen plasma (FFP) should be administered until plasmapheresis can be performed. The patient's fetus is nonviable at 20 weeks gestation (A) and cannot be delivered. If the fetus is viable, delivery is an option. However, the patient is at high risk for bleeding complications. Medical therapy and plasmapheresis are the first lines of treatment. Magnesium sulfate (B) is used in the treatment of eclampsia. Although this patient had a seizure, her blood pressure is normal and her lab results are more consistent with TTP than eclampsia. Although platelet levels are low in TTP, platelet transfusion (D) is reserved only for patients with life-threatening bleeding. Any administration of platelets will result in destruction from platelet aggregation in the microvascular circulation.

A 14-year-old African American girl with sickle-cell disease presents with symptoms consistent with vaso-occlusive crisis. She has had progressive pain in her lower extremities and back for 2 days. She has been alternating acetaminophen and hydrocodone at home without relief. She denies chest pain, cough, dyspnea, or fever. Her vital signs are within normal limits, and oxygen saturation is 96% on room air. Her labs reveal a hemoglobin level of 5 g/dL (baseline 7.5 g/dL) and a reticulocyte count of 1% (baseline 8%). In addition to analgesia, what management measures should be taken? Begin blood transfusion, and admit patient to the ICU Initiate fluid resuscitation with isotonic saline, and admit if pain is not relieved after 3 rounds of opioid analgesics Place patient on droplet precautions, transfuse blood, and admit to hematology service for continued blood transfusions Place patient on oxygen, obtain a chest X-ray, and start empiric antibiotics

Correct Answer ( C ) Explanation: The patient is having an aplastic crisis, mostly likely due to Parvovirus B19. Parvovirus B19 is associated with transient red cell aplasia and is virtually unnoticed in healthy patients. However, in patients with high red cell turnover states (i.e., sickle-cell disease), the virus can be life-threatening and cause an aplastic crisis. This patient has a decrease in her baseline hemoglobin and a precipitous drop in her reticulocyte count, indicating an aplastic crisis. Parvovirus B19 is also associated with hydrops fetalis in pregnant women; therefore, appropriate management includes placing the patient on droplet precautions. Additional management for transient red cell aplasia includes consultation with a hematologist, blood transfusion, and in cases of chronic B19 infection and chronic anemia, admission for intravenous immunoglobulin therapy (IVIG). Splenic sequestration is another potentially life-threatening condition in sickle-cell patients. It is diagnosed by splenic enlargement and labs not consistent with aplasia (elevated reticulocyte count) or hemolysis (nonelevated lactate dehydrogenase, AST, indirect bilirubin). Patients with splenic sequestration need an immediate blood transfusion and likely disposition to the ICU (A). Acute chest syndrome is the leading cause of mortality among patients with sickle-cell disease. It is diagnosed by fever, cough, chest pain, dyspnea, and new infiltrates on chest X-ray. Management of acute chest syndrome is supportive and includes oxygen, if hypoxic, and empiric antibiotics (D). Intravenous hydration with isotonic fluid is necessary only to replete intravascular volume if there is a clinical concern for volume depletion (B). Some clinicians advocate initiating fluid resuscitation with hypotonic fluid (1/2 NS) at 1.5-2 times the maintenance rate for patients in pain crises. Patients whose pain is not well controlled in the ED will require admission for further pain control.

A 72-year-old woman with chronic myelogenous leukemia and congestive heart failure with an ejection fraction of 30% is brought to the ED by her son for altered mental status. The patient complains of blurred vision, headache, and fatigue. On exam, she appears confused. Labs reveal WBC 157,000/mm3, hemoglobin 8 g/dL, and platelets 78,000/mm3. Her peripheral smear is seen above. What is the next best step in the treatment of this patient? Fluid resuscitation Hemodialysis Leukapheresis Red blood cell transfusion

Correct Answer ( C ) Explanation: This patient has hyperviscosity syndrome. The syndrome is characterized by sludging and leads to decreased perfusion secondary to increased products (paraproteins, RBCs, and WBCs) in the bloodstream. Most commonly, this is caused by a malignancy that results in hyperproduction of a cell line. In this case, the patient has a blast crisis in a previously indolent leukemia and is now experiencing sludging in the microcirculation, which has caused local ischemia. The presenting symptoms can be subtle and most commonly include altered mental status, fatigue, and headache. White blood cell counts >100,000/mm3, or leukocrits >10% are usually found. The Initial treatment is usually aggressive fluid resuscitation or phlebotomy with replacement with intravenous fluids. However, in patients who may not be able to tolerate large volumes of fluid, leukapheresis is the primary treatment when there is a blast transformation, as seen in this patient. When the hyperviscosity is due to a dysproteinemia, such as multiple myeloma or Waldenstrom macroglobulinemia, the treatment is plasmapheresis.Fluid resuscitation (A) is usually the first step in hyperviscosity syndrome, except when patients have comorbidities that do not allow for large volumes of fluids. Because this patient has heart failure with a poor ejection fraction, fluid resuscitation should be avoided, and the patient should undergo emergent leukapheresis. Hemodialysis (B) does not remove the excess cells causing the hyperviscosity. A red blood cell transfusion (D) will likely worsen the viscosity and should be avoided.

A 52-year-old man with a recent diagnosis of hypertension complains of intense itching after taking hot showers. He also reports increasing fatigue over the prior four months. His review of systems is otherwise normal and takes propranolol for his hypertension. What physical exam finding is most consistent with his diagnosis? Pallor Petechiae Plethora Purpura

Correct Answer ( C ) Explanation: This patient is most likely suffering from primary polycythemia vera, a condition in which unregulated production of blood cells leads to erythrocytosis (Hct >60%). Clinically, its onset is usually slow and progressive, marked by complications of sludging, thrombosis, or infarction in the peripheral circulation. Early signs of polycythemia vera include hypertension, plethora (a ruddy complexion), and itching after hot showers due to histamine release from increased basophil and mast cell production. Splenomegaly and hepatomegaly are also commonly found on physical exam. Late findings include headache, fatigue, vertigo, chest pain, claudication, and vision changes. Pallor (A), is typically a sign of anemia, the opposite problem facing patients with polycythemia vera. Petechiae (B) and purpura (D) are caused by similar processes, including thrombocytopenia, platelet dysfunction, coagulation factor deficiencies, trauma to small blood vessels, or vasculitis. None of these pathways is consistent with polycythemia vera.

A 44-year-old man is transferred from a nursing facility for thrombocytopenia. He was transferred 6 days ago for pulmonary embolism and is on low-molecular weight heparin. His platelets have decreased from 352 to 100. There is no active bleeding at this time. Which of the following is the most likely management indicated? Continue current therapy Order heparin-induced platelet aggregation studies and continue therapy while awaiting results Stop low-molecular weight heparin and start fondaparinux Transfuse platelets

Correct Answer ( C ) Explanation: This patient presents with heparin-induced thrombocytopenia (HIT) requiring immediate cessation of heparin. HIT is an immune-mediated side effect of heparin. It occurs in 0.5 - 2.6% of patients receiving unfractionated heparin and is less common in patients receiving low-molecular weight heparins (<1%). It usually occurs within 5 to 7 days of initiation of therapy. Thrombotic complications are serious and can lead to limb loss in 20% and death in 30%. Diagnosis is made by a drop in platelets by 50% after heparin is started. Serotonin release assays and heparin-induced platelet aggregation assays can confirm the diagnosis. Management focuses on stopping the offending agent (unfractionated or low-molecular weight heparin) and starting a non-related anticoagulant if continued therapy is indicated. Typically, direct thrombin inhibitors (lepirudin, argatroban), factor Xa inhibitors (fondaparinux) or heparinoids (danaproid) are indicated for continued treatment. Although asymptomatic thrombocytopenia does not require therapy at a level of 100, HIT should not be managed by continuation of therapy (A) because of the rate of complications. Therapy should not be continued while awaiting testing (B) as a presumptive diagnosis can be made based on the drop in platelets and heparin treatment. Platelet transfusion (D) is contraindicated unless life-threatening bleeding is present.

63-year-old man presents to the ED two days after his last chemotherapy session for induction treatment of acute myelogenous leukemia. He has been vomiting and having diarrhea since his last session. He reports feeling dehydrated and unable to tolerate oral intake. What labs are consistent with a diagnosis of tumor lysis syndrome for this patient? High calcium, high phosphate, high potassium High calcium, low phosphate, low potassium Low calcium, high phosphate, high potassium Low calcium, low phosphate, low potassium

Correct Answer ( C ) Explanation: Tumor lysis syndrome occurs within a few hours to a few days after the initiation of chemotherapy or radiation therapy to treat bulky tumors. It is most commonly seen after chemotherapy of hematologic malignancies, including acute leukemias and high-grade non-Hodgkin's lymphomas, particularly Burkitt's lymphoma. Biochemical hallmarks of this syndrome include hyperkalemia from cytosol breakdown, hyperphosphatemia from protein breakdown, and hypocalcemia secondary to the hyperphosphatemia.

A 55-year-old woman is receiving a blood transfusion due to persistent vaginal bleeding and a hemoglobin of 5 mg/dL. While receiving the transfusion, she develops fever, chills, back pain, pain at the site of transfusion, and tachycardia. After stopping the transfusion, which of the following is the most important therapy to administer next? Acetaminophen Diphenhydramine Intravenous hydration Solu-Medrol

Correct Answer ( C ) Explanation: Up to 20% of all transfusions may lead to some type of adverse reaction. Although most of these reactions are minor, some are life-threatening. The patient is having an acute intravascular hemolytic reaction. This occurs when the recipient's antibodies recognize and induce hemolysis of the donor's red blood cells. In this reaction, most of the transfused cells are destroyed, which may result in activation of the coagulation system and disseminated intravascular coagulation. This type of reaction typically presents with back pain, pain at the site of transfusion, headache, fever, hypotension, dyspnea, tachycardia, chills, bronchospasm, pulmonary edema, bleeding, and development of renal failure. The first step is to stop the transfusion. It is then important to initiate intravenous hydration to maintain diuresis. Vital signs should also be monitored due to the potential for hypotension. Acetaminophen (A) can be administered to patients who develop an isolated fever during the transfusion. If this occurs, it is important to stop the transfusion and make sure there is not a more severe reaction occurring. The blood bank should be notified. Diphenhydramine (B) can be administered in mild reactions and should be accompanied by cessation of the transfusion and further investigation into a more serious reaction. Solu-Medrol (D) can be administered in patients with moderate to severe allergic reactions.

A 5-year-old boy with a history of sickle cell anemia presents with dyspnea and fatigue. Mom notes that one week prior he had a fever, headache and bright red rash on his cheeks which has since resolved. Laboratory studies show a decrease in his baseline hemoglobin by 30%. Infection with which virus likely precipitated his current symptoms? Coxsackie virus Human herpesvirus 6 Measles virus Parvovirus B19

Correct Answer ( D ) Explanation: Erythema infectiosum is a generally benign, self-limiting disease that affects young children ages 4 to 10 years. It is caused by parvovirus B19. After a brief, mild prodrome of malaise and low-grade (if any) fever, patients develop a characteristic facial rash with a "slapped-cheek" appearance. One to four days later, the rash spreads to the trunk and extremities and takes on a lacy appearance. While most children recover in a week, certain children with a history of hematologic abnormalities, such as sickle cell anemia, may develop transient aplastic crisis due to a marked reduction of erythroid cell precursors. These patients may present with onset of pallor, fatigue, lethargy, and shortness of breath due to anemia. Laboratory studies will show an undetectable reticulocyte count and a drop in hemoglobin concentration of > 30%. Anemia is often severe enough to require transfusion. Fortunately, as the name suggests, transient aplastic crisis is self-limited as red cell production returns to normal once the infection has cleared (typically in one to two weeks). Coxsackie virus (A) is the primary virus responsible for hand, foot and mouth disease. Young children present with a painful oral enanthem found on the tongue and buccal mucosa. The skin lesions are generally non-pruritic and may be macular, papular, or vesicular. Human herpesvirus 6 (B) is the virus responsible for roseola. The illness begins with the abrupt onset of a high fever followed three to five days later with the appearance of a fine, rose-colored maculopapular rash on the trunk, extremities, and face. The rash appears after the child defervesces. Measles (C) is a highly contagious viral illness that begins with a prodrome of fever, malaise, conjunctivitis, coryza, and cough. An erythematous, blanching rash then develops on the face and neck before spreading caudally. None of these viruses are likely to have precipitated transient aplastic anemia in this child.

A 36-year-old woman is undergoing chemotherapy for her breast cancer. She is very concerned about the risk of neutropenic fever and wonders if the recent appearance of myalgias and a low-grade temperature (38°C) are signs of this. How many days after her chemotherapy session should she experience a nadir in her absolute neutrophil count? 15 days 21 days 3 days 7 days

Correct Answer ( D ) Explanation: For the majority of chemotherapy regimens, the nadir in the absolute neutrophil count (ANC) will occur five to 14 days after completion of a chemotherapy session.

A 49-year-old man presents with mental status changes and fever. Brain CT scan is normal. His urine toxicology screen is negative. Laboratory findings show a serum sodium of 137 mEq/L, serum potassium of 5.1 mEq/L, serum creatinine of 1.9 mg/dL, WBC of 9 000/L, hemoglobin of 9.3 g/dL, and platelets of 19 000/L. Which of the following would you expect to see on skin examination? Acanthosis nigricans Erythromelalgia No abnormalities Purpura

Correct Answer ( D ) Explanation: Hemolytic-uremic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP) are microvascular thrombotic disorders associated with platelet aggregation, thrombocytopenia, erythrocyte injury, and elevated serum lactate dehydrogenase levels. They both present with microangiopathic hemolytic anemia, thrombocytopenia, and renal failure, but TTP may have concurrent neurologic abnormalities and fever. Both diseases are associated with thrombocytopenia that often leads to purpura, petechiae, and bleeding. HUS usually occurs in children 5-10 days after an episode of E. coli-induced bloody diarrhea, in which the shiga toxin activates platelets and renovascular cells leading to thrombosis. TTP usually occurs in adults and can be idiopathic or secondary to drugs, autoimmune disease, pregnancy, or HIV. In TTP, the pathophysiology is based on an inhibition of the enzyme ADAMTS13, which leads to large multimers of von Willebrand factor. The exact distinction between HUS and TTP can be difficult; they share common symptoms. As in any hemolytic state, the peripheral blood smear will have schistocytes (fragmented erythrocytes, also called helmet cells). If either condition is suspected, urgent plasmapheresis (remove plasma and replace with fresh frozen plasma) is performed daily for 1-8 weeks until the lactate dehydrogenase or hemoglobin normalizes. Consider administering corticosteroids for inadequate response to plasmapheresis and splenectomy for recurrent cases. Prompt recognition of TTP is important because the disease responds well to plasma-exchange treatment but is associated with a high mortality rate when untreated Acanthosis nigricans (A) is a brown-black, velvety hyperpigmentation, typically found in the body folds of patient's with obesity, insulin-resistant diabetes, hypothyroidism, acromegaly, and Cushing's disease. Erythromelalgia (B) is a microvascular, thrombi-induced hyperemia associated with polycythemia vera. It occurs intermittently in the distal extremities and can be quite painful. Abnormalities (C) are expected, as discussed in the explanation.

Which of the following tests is suggestive of the diagnosis of iron-deficiency anemia? Basophilic stippling Decreased serum haptoglobin Mean corpuscular volume >100 fL Serum ferritin <15 mcg/L

Correct Answer ( D ) Explanation: Iron-deficiency anemia is a common cause of chronic anemia. Symptoms can lag behind the development of the disease because changes to RBC size and hemoglobin content only occur after cytochrome and bone marrow iron stores are depleted. The majority of iron in the body is stored in hemoglobin, the reticuloendothelial system, myoglobin and bound to transferrin. Women possess less hemoglobin and myoglobin and have lower iron stores making them more susceptible to iron-deficiency anemia. There are two major etiologies of iron-deficiency: iron-store depletion and malabsorption. The prior usually involves growth in infants and adolescents, inadequate daily intake and menstruation. Malabsorption involves processes like sprue, gastrectomy and inflammatory bowel disease. Diagnosis is made by laboratory testing that is usually triggered by the presence of hypochromic, microcytic anemia. Diagnostic studies include a fasting serum iron (<50 mcg/dL), transferrin saturation percent (<10%), serum ferritin (<15 mcg/L) and total iron-binding capacity (> 400 mcg/dL) in the setting of decreased mean corpuscular volume (MCV). Depressed serum ferritin levels indicate depleted total body iron stores. These patients will also have decreased reticulocyte counts as the building blocks for new RBCs are diminished. Basophilic stippling (A) is a common finding in lead toxicity causing sideroblastic anemia. A decreased serum haptoglobin (B) is seen in inherited hemolytic anemias (i.e. hereditary spherocytosis, glucose-6-phosphate dehydrogenase deficiency) when acute hemolytic crisis develops. A mean corpuscular volume over 100 fL (C) is indicative of macrocytic anemia, not microcytic anemia.

Which of the following indices reported in a standard complete blood count panel is most helpful to differentiate between iron deficiency anemia and thalassemia? Mean corpuscular hemoglobin (MCH) Mean corpuscular hemoglobin concentration (MCHC) Mean corpuscular volume (MCV) Red blood cell distribution width (RDW)

Correct Answer ( D ) Explanation: Red blood cell distribution width (RDW) is a measure of the deviation in volume of the RBCs. It is calculated by dividing the standard deviation of the MCV by the mean MCV and multiplying by 100. RDW = (SD MCV/mean MCV) x 100. It is useful in differentiating thalassemia from iron deficiency anemia. The RDW is usually increased in iron deficiency and normal in thalassemia. Mean corpuscular hemoglobin (MCH) (A) is a measure of the hemoglobin content within a RBC and is calculated by dividing the hemoglobin concentration by the red blood cell count. It is usually low in both iron deficiency and thalassemia anemia. Mean corpuscular hemoglobin concentration (MCHC) (B) is a measure of the concentration of hemoglobin within the RBC. It is calculated by dividing the hemoglobin concentration by the hematocrit. It is expected to decrease in both iron deficiency and thalassemia anemia. Mean corpuscular volume (MCV) (C) is a measure of RBC size. It is also expected to decrease in both thalassemia and iron deficiency anemia.

A 3-year-old girl who was recently adopted from abroad is brought to the ED by her new parents for evaluation of fatigue and pallor. The patient's medical history and family medical history are unknown. Her lab results are as follows: White blood cells: Normal Hemoglobin: Very low Platelets: Normal Mean corpuscular volume: Very low Reticulocyte count: Normal Ferritin: Normal Which of the following is the most likely cause of her anemia? Chronic disease Iron deficiency Lead poisoning Thalassemia

Correct Answer ( D ) Explanation: This patient is most likely suffering from alpha thalassemia coupled with some form of oxidative stress causing worsening of her baseline anemia. Alpha thalassemia occurs when 1 or more of the 4 alpha globin chain genes fails to function. These patients usually have chronic, hypochromic, microcytic anemia, as evidenced by her low MCV. The WBC, platelet count and markers of iron storage and reticulocytosis are typically normal. Patients with thalassemia who receive recurrent blood transfusions have elevated markers of iron and iron storage and are at risk for iron toxicity. In patients with alpha thalassemia minor or major, oxidative stress can lead to jaundice from hemolysis, splenomegaly from increased sequestration, and hemodynamic instability. Anemia of chronic disease (A) is associated with a microcytic anemia, low reticulocyte count, and high ferritin. Iron deficiency anemia (B) is also associated with microcytic anemia, low reticulocyte count, and low ferritin level. Lead poisoning (C) is associated with normocytic or microcytic cells with evidence of hemolysis, elevated reticulocyte count, and normal to increased ferritin levels.

A patient with hemophilia B presents with hemarthrosis of the left elbow. Which of the following is the most appropriate management indicated? Cryoprecipitate Desmopressin Factor VIII concentrate Recombinant factor IX

Correct Answer ( D ) Explanation: This patient presents with hemarthrosis and a history of hemophilia B or factor IX deficiency requiring treatment with recombinant factor IX. Hemophilia B or Christmas disease is an X-linked recessive bleeding disorder. The genetic alteration results in a deficiency of factor IX activity. It is genetically and clinically indistinguishable from hemophilia A but is far less common. The most common clinical presentation is hemarthrosis with minor trauma but internal bleeding with minor head, chest or abdominal trauma can be seen as well. Historically, treatment involved the use of fresh frozen plasma. More recently, plasma prothrombin complex (factors II, VII, IX and X) and recombinant factor IX have become available and have less side effects. If available, recombinant factor IX is the preferred treatment. Correct Answer ( D ) Explanation: This patient presents with hemarthrosis and a history of hemophilia B or factor IX deficiency requiring treatment with recombinant factor IX. Hemophilia B or Christmas disease is an X-linked recessive bleeding disorder. The genetic alteration results in a deficiency of factor IX activity. It is genetically and clinically indistinguishable from hemophilia A but is far less common. The most common clinical presentation is hemarthrosis with minor trauma but internal bleeding with minor head, chest or abdominal trauma can be seen as well. Historically, treatment involved the use of fresh frozen plasma. More recently, plasma prothrombin complex (factors II, VII, IX and X) and recombinant factor IX have become available and have less side effects. If available, recombinant factor IX is the preferred treatment.

Which of the following conditions is associated with a normal platelet count? Disseminated intravascular coagulation Hemolytic uremic syndrome Systemic lupus erythematosus Thrombotic thrombocytopenic purpura Von Willebrand disease

Correct Answer ( E ) Explanation: Von Willebrand disease (vWD) is the most common hereditary bleeding disorder and is present in 1% of the population. It is caused by abnormal von Willebrand factor (vWF), which serves two key roles in normal hemostasis. It is a cofactor for platelet adhesion, as well as the carrier protein for factor VIII. Skin and mucosal bleeding symptoms are common in people with vWD, particularly in children and adolescents. This includes recurrent epistaxis, gingival bleeding, bruising, GI bleeding, and menorrhagia in young women. Hemarthosis is not typical unless severe disease is present. VWD is associated with a normal platelet count, normal aPTT/PT, and prolonged bleeding time. Disseminated intravascular coagulation (DIC) (A) is widespread activation of the coagulation and fibrinolytic cascade, leading to a life-threatening bleeding disorder. It is associated with a prolonged aPTT/PT, low platelet count, low fibrinogen level, elevated fibrin degradation products, elevated D-dimer, increased thrombin time, and decreased antithrombin III levels. Microangiopathic hemolytic anemia is invariably present and, accordingly, schistocytes are commonly seen on peripheral blood smear. Hemolytic uremic syndrome (HUS) (B) is usually preceded by infectious diarrhea and is strongly associated with the O157:H7 strain of enterohemorrhagic E. coli. Microangiopathic hemolytic anemia with renal failure is the hallmark of HUS, often with accompanying platelet destruction. Systemic lupus erythematosus (C) is a collagen vascular disease associated with increased platelet destruction, leading to chronic thrombocytopenia. Patients with thrombotic thrombocytopenic purpura (TTP) (D) classically present with some combination of the pentad that includes fever, anemia, thrombocytopenia, renal failure, and neurologic problems. Rarely are all five seen on presentation. Platelet transfusion is associated with rapid deterioration and should not be administered in patients with TTP.