Hematologic Pathology

Anemia of Chronic Disease (ACD) -The 3 C's

"3 C's": 1) Chronic infections: -osteomyelitis, bacterial -endocarditis, lung -abscess 2) Connective tissue diseases: -RA, SLE, regional enteritis - crohn's 3) Cancer -Hodgkin lymphoma, lung and breast cancer also other cancers

Macrocytic Anemia -Histology

- ^'d RBC size (^'d MCV) -normochromia -considerable anisocytosis. -Hypersegmented nuclei: neutrophils & Eos. -Reticulocytes are low -nucleated red cells (NRBC's) occasionally appear in circulating blood with severe anemia. -Marrow is usually markedly hypercellular dt ^'d numbers of all types of myeloid precursors. Picture Shows: Megaloblastic anemia (bone marrow aspirate). A to C, Megaloblasts in various stages of differentiation. Note that the orthochromatic megaloblast (B) is hemoglobinized (as revealed by cytoplasmic color), but in contrast to normal orthochromatic normoblasts, the nucleus is not pyknotic. The granulocytic precursors are also large and have abnormally "immature" chromatin.

G6PD Deficiency -Sx development

- usually asymptomatic until hemolysis occurs after exposure to an agent that causes oxidant damage. -Acute intravascular hemolysis usually takes 2-3 days to develop after such an exposure. -The potential for life threatening hemolysis does exist but since older cells are most affected, the hemolytic anemia is usually mild and self-limited. Picture shows: - effects of oxidant drug exposure (peripheral blood smear). -Inset: Red cells with precipitates of denatured globin (Heinz bodies) revealed by supravital staining. -As the splenic macrophages pluck out these inclusions, "bite cells" like the one in this smear are produced.

Sickle Cell Anemia -Complications * Pain Crisis * Sequestration Crisis * Aplastic Crisis

-"Pain crisis" (vaso-occlusive crisis) * the term given to bone ischemia/infarction. -Treatment is with: * oxygen * hydration * narcotics * blood transfusions if necessary. -Sequestration crisis: * sequestration of RBCs by the spleen, resulting in acute splenic enlargement, hypovolemia and shock. * occurs in children with sickle cell anemia -Aplastic crisis: * a condition in which there is marked suppression of BM * often due to infection by the Parvo B19 virus.(Fifth's Disease)

Hematopoeisis -Cells

-A common stem cell- pluripotent stem cell, gives rise to the full line of blood cells. -This line includes: RBCs, WBCs (neutrophils, lymphocytes, eosinophils, monocytes and macrophages), platelets, plasma cells, mast cells, NK cells, B cells and T cells. * These are mature progeny, have finite life spans, must constantly be replenished. * Stem cells are cells found in all multi cellular organisms. They are characterized by the ability to renew themselves through mitotic cell division

Abnormal Hemoglobin -Sickle Cell Anemia

-A genetically determined biochemical anomaly in the chain of hemoglobin produces an altered solubility. -Sickle cell anemia results from a single point mutation in β-globin -Resultant hemoglobin is termed Hgb S -Sickle cells are formed dt: * a low pH * decreased oxygen tension -Initially reversible with oxygenation, prolonged deoxygenation results in the permanent deformation of the sickled cells. -Deoxygenation and sickling occurs more readily in acidic tissues because a low pH reduces oxygen's affinity for hemoglobin.

Peripheral Smear of HUS

-A peripheral blood smear from a patient with hemolytic-uremic syndrome shows several fragmented red cells. -Classic childhood case of HUS occurs after bloody diarrhea caused by E. coli O157:H7. -The toxin enters the bloodstream, attaches to renal endothelium and initiates an inflammatory reaction- ARF) and -DIC -The fibrin mesh destroys RBC and captures PLTs, leading to a decrease of both on complete blood count. The usual age of onset is between 2 and adolescence.

Abnormal RBC Metabolism

-Abnormal RBC metabolism is caused by: * enzymatic defects * membrane structure defects. -The classic example of red cell membrane defect is Hereditary Spherocytosis (HS).

Sickle Cell Disease

-About 8% of American blacks are heterozygous for Hb S and are termed as carriers or sickle cell trait with 40% HbS & 60% normal Hgb. -Homozygous: * almost all of the Hb in each RBC is Hgb S and the condition is called sickle cell anemia (or disease). -In the US approx 2 million Americans have the trait. -In the US, about 1 in 500 African-Americans develops sickle cell anemia -In Africa, about 1 in 100 develops the disease -Newborns have a period of protection of several months from deoxygenation dt concentrations of fetal Hgb. -Sickled cells have a shortened life span of approximately 20 days.

Aplastic Anemia -Congenital vs. Acquired

-Acquired causes account for ~80% of cases -Congenital or inherited causes ~20% of cases * Examples include + Fanconi's anemia + Familial aplastic anemia. -Fanconi's anemia is an autosomal recessive inherited disease that mainly affects the bone marrow. It results in decreased production of all types of blood cells -Fanconi's anemia (FA) incidence of 1 per 350000 births, and a higher frequency in Ashkenazi Jews and Afrikaners in South Africa

Extrinsic Hemolytic Anemia -Acquired Hemolytic Anemias

-Acquired hemolytic anemias - the result of immunologic (autoimmune) mediated RBC destruction -Ab's are usually of the IgG class * directed against RBCs with direct cell lysis * react with RBC membranes to increase their susceptibility to spleen destruction -Autoimmune process may be: * primary (idiopathic) * secondary to an underlying disease such as lymphoma * carcinoma * sarcoidosis * collagen vascular disease - Lupus or rheumatoid arthritis. -Immune hemolysis causes: * incompatible blood transfusions * fetal maternal incompatibility

Aplastic Anemia -Symptoms

-Anemia may manifest as: * pallor * headache * palpitations * dyspnea * fatigue. -Thrombocytopenia may present as: * mucosal and gingival bleeding * petechial rashes. -Neutropenia may manifest as: * overt infections * recurrent infections * mouth and pharyngeal ulcerations.

Sickle Cell Anemia -Hgb Concentration

-Another aspect of the pathogenesis is dependent on the concentration of Hgb per cell (MCHC) mean corpuscular hemoglobin concentration. -Intracellular dehydration ↑ MCHC facilitating sickling and vascular occlusion. -Conditions ↓ MCHC (alpha-thalassemia) - pts. will have milder sxs/dz because thalassemia reduces globin synthesis ↓ the hgb conc. per cell.

Aplastic Anemia -Definition -Complications

-Aplastic anemia is the failure of the pluripotential stem cells to produce RBCs, WBCs, and megakaryocytes. -The major causes of morbidity and mortality from aplastic anemia include INFECTION and BLEEDING. -Patients who undergo bone marrow transplantation (BMT) have additional issues related to conditioning regimen toxicity and graft versus host disease.

Sickle Cell Anemia -Prognosis

-Approximately 90% of Homozygous sickle cell anemia patients now survive into their twenties. -Approximately 50% of sickle cell patients survive beyond their 50's. -Common causes of death include * overwhelming infection * pulmonary emboli * renal failure -Heterozygotes have approximately 60% normal hemoglobin, thus are usually asymptomatic. -Painless hematuria -Symptoms can arise at very high altitudes or after marked exertion.

Pernicious Anemia -Role of Autoantibodies

-Believed that an autoreactive T-cell response initiates GASTRIC mucosal INJURY, triggering formation of autoantibodies, which then cz gastric mucosal destruction. 3 types of Ab's found: 1) type I that blocks binding of B-12 to IF 2) type II prevents binding of IF-B-12 complex to its ileal receptor 3) type III not specific to PA but are found in up to 50% of elderly pts with chronic gastritis -Other disorders that interfere with the absorption and metabolism of vitamin B-12 can produce cobalamin (Cbl) deficiency, with the development of a macrocytic anemia and * the potential for neurological complications. -Anti-parietal cell Ab's occur in 90% of patients with pernicious anemia compared to only 5% of healthy adults. Dietary Cbl -is acquired mostly from meat and milk -is absorbed in a series of steps which require proteolytic release from foodstuffs & binding to Intrinsic Factor (IF).

Hemolytic Anemias - Extrinsic -Cold Aglutination AIHA * Pathogenesis

-Binding of IgM to RBCs at sites of cold exposure (fingers, toes, ears, nose). -IgM binding agglutinates RBCs & rapidly FIXES COMPLEMENT on their surface. -As the blood circulates and warms the IgM is released. -Raynaud phenomenon - vascular obstruction causes pallor & cyanosis of affected parts.

Hemolytic Anemias - Extrinsic -Cold Aglutination AIHA

-Caused by IgM Abs that bind and agglutinate RBCs at low temps (0 - 4 C). -Accounts for 15-30% of these types of anemia. -Abs appear acutely during recovery phase of infectious d/o's (mycoplasma pneumonia & mono, HIV, CMV, influenza virus). -Here the d/o is self-limiting and rarely causes clinical manifestations of hemolysis. -Chronic aspects of this condition occur with certain lymphoid neoplasms or idiopathically.

Alpha Thalassemia Major

-Caused by deletion of 3 alpha-globin genes. -Seen commonly in Asian populations. -HbH is formed dt tetramers of excess beta-globin. -HbH has a high affinity for oxygen and DOES NOT ALLOW FOR O2 EXCHANGE > leading to tissue hypoxia. -HbH is also prone to oxidation leading to intracellular inclusions (Heinz Bodies & bite cells) -This produces a moderate anemia.

Iron Deficiency Anemia -Chronic Blood Loss

-Chronic blood loss is the most common cz in the western world. -Internal hemorrhage * GI tract + (PUD, hemorrhagic gastritis, gastric or colorectal carcinoma, hemorrhoids, parasites) * GU + (renal, pelvic or bladder tumors) * Gyn + (menorrhagia, AUB, Uterine carcinoma) depletes iron stores.

Hydrops Fetalis

-Deletion of all four of the genes coding for the alpha globin chains is incompatible with life. -Unless intrauterine transfusions are given to the fetus, death occurs due to tissue hypoxia. -Fetus shows marked pallor and generalized edema.

Iron Absorption

-Diagram is a representation of iron absorption. Mucosal -uptake of heme and nonheme iron is depicted. -When the storage sites of the body are replete with iron and erythropoietic activity is normal, most of the absorbed iron is lost into the gut by shedding of the epithelial cells. -Conversely, when body iron needs increase or when erythropoiesis is stimulated, a greater fraction of the absorbed iron is transferred into plasma transferrin, with a concomitant decrease in iron loss through mucosal ferritin.

Iron Deficiency Anemia -Dietary Deficiency

-Dietary lack: most common in developing countries dt predominantly vegetarian diet. -Industrialized countries have diets with 2/3 of dietary iron in readily assimilable heme form (animal origin forms) -Dietary lack occurs more often in infants, children, the poor and the elderly.

Sickle Cell Anemia -Treatments

-Erythropoietin (EPO) is one method of treating sickle cell anemia by increasing RBC production & diminishing anemia. * Frequency of pain crises appears lowered but long term effects are not known. -The supplement, butyrate also appears to diminish sickling. -Studies using both L-arginine or Sildenafil (Viagra) as vasodilators are ongoing. * ACT VIA INCREASED NITRIC OXIDE LEVELS! -Another novel approach to the treatment of sickle cell anemia is the use of the drug hydroxyurea. * FDA approved in 1998 (1) * Hydroxyurea is a chemotherapeutic agent that works by disrupting DNA replication. * Hydroxyurea has 3 different mechanisms: 1) anti-inflammatory: inhibiting production of WBC's 2) ^'d mean RBC volume and decreased conc. of HbS 3) can be oxidized by heme groups to produce NO * Hydroxyurea appears to convert part of Hgb S to Hgb F + Hgb F concentrations of 10-15%of the total Hgb decrease incidence of vaso-occlusive complications.

G6PD Deficiency -Genetics

-G6PD deficiency is an X-linked disorder expressed in all erythrocytes of an affected male. -In the heterozygous female there will be two populations of RBCs, some deficient in the enzyme, some normal. -In most cases, the defect is in enzyme stability and not enzyme synthesis.

HbSC Disease

-HbC has a greater tendency to form aggregates with deoxygenated HbS and HbA - HbSC disease. -HbSC disease has milder sxs than full on sickle cell anemia. -Hematuria, retinal hemorrhages and aseptic necrosis of femoral head occur. -2%-3% of American blacks are asymptomatic HbC/HbA heterozygotes -About 1 in 1250 has HbSC disease.

Hemoglobin C Disease & Trait

-Hemoglobin C is another variant of hemoglobin. -Similar to Hb S, Hb C is seen in the U.S. almost entirely in the African-American population. -Heterozygotes (Hb AC) have Hb C TRAIT although the term hemoglobin C disease is often used to refer to both heterozygotes and homozygotes (Hb CC). -Incidence is ~2-3% of African-Americans. -Patients with Hb C trait (Hb AC) are usually asymptomatic and might only show target cells.

Hemolytic Anemia -Site of Hemolysis

-Hemolysis of aged RBCs takes place within spleen mononuclear phagocytic cells. -The spleen is also the site of RBC destruction in the majority of hemolytic anemias. -The exception to this rule is when hemolysis of RBCs takes place primarily within the vascular compartment itself. -Hemolytic anemias: * Intravascular - within bv's * Extravascular - hemolysis in the SPLEEN

Hereditary Spherocytosis -Cause -Results of defect for RBCs

-Hereditary spherocytosis: an inherited disorder resulting in an intrinsic defect in the red blood cell membrane. -This defect causes: * RBCs spherical in shape * less deformable in the vasculature * more vulnerable to splenic sequestration and destruction by macrophages. -RBC membrane exhibits increased osmotic fragility which can result in membrane rupture. -HS is usually an autosomal dominant condition (75% of cases) which most often affects individuals of Northern European ancestery. -Prevalence rates in this population approach 1 in 5000 individuals. -An autosomal recessive variant form of HS exists (25% of cases) which is much more severe in clinical presentation.

Hemoglobin E Disease

-Hgb E is the third most common form of Hgb worldwide. -Hgb E is most commonly found in Southeast Asians. -Heterozygotes with Hgb AE are asymptomatic. -Homozygotes for Hgb EE exhibit mild microcytic anemia and target cells.

Pernicious Anemia -Health Effects

-In adults, pernicious anemia is associated with: * severe gastric atrophy & achlorhydria, which are often irreversible. -Coexistent iron deficiency is common because achlorhydria prevents the solubilization of dietary ferric iron from foodstuffs. -Gold standard of diagnosis: endoscopy directed biopsy of gastric mucosa showing depleted parietal cells.

Aplastic Anemia -Acquired

-Infectious causes such as: * hepatitis viruses * Epstein-Barr virus (EBV) * HIV * Parvo B19 * mycobacterial infections. -Toxic exposure to * radiation * chemicals such as benzene. -Drugs such as: * chloramphenicol * sulfa * gold -Many cases have no known etiology and are referred to as idiopathic.

Hemolytic Anemia -Intravascular Hemolysis

-Intravascular hemolysis is a result of: * mechanical trauma: + mechanical heart valves + physical trauma (marathon running, bongo drumming)) * antibody fixation: + mismatched bld transfusion * toxic injury to the RBCs: + malaria + septic shock -Peripheral smear of a patient with intravascular hemolysis usually shows numerous fragmented RBC's. -The irregular shapes appear as "helmet" cells, or fragmented "schistocytes".

Intrinsic Hemolytic Anemias

-Intrinsic hemolytic anemias are congenital. -It is common with intrinsic hemolytic anemias to have a positive family history for anemia. -The Intrinsic hemolytic anemias may be divided into anemias due to: * Abnormal hemoglobin * Abnormal RBC metabolism * Abnormal hemoglobin synthesis

Anemias of Diminished Erythropoiesis

-Megaloblastic anemia: B-12 and folate deficiency anemia -Iron deficiency anemia (IDA) -Anemia of chronic disease (ACD) -Anemia of renal failure -Marrow stem cell failure (aplastic and pure red cell aplasia anemias)

Hemolytic Anemias - Extrinsic -Warm Antibody AIHA

-Most common form of AIHA -50% of cases are idiopathic -50% are secondary from: * SLE * Rx * neoplastic dzs like lymphoma. -Most causative Ab is IgG class (s/t IgA) Pathogenesis: -IgG-coated RBCs bind Monocyte & spleen Macrophage Fc receptors --> RBC membrane loss. -RBCs --> spherocytes during partial phagocytosis. -They are then sequestered and removed in the spleen, therefore splenomegaly is present.

B-12 Deficiency

-Neurological symptoms and findings may be present in the absence of anemia * this is more common in patients taking folic acid or on a high-folate diet. -Patients who are older may present with symptoms suggesting senile dementia or Alzheimer disease; memory loss, irritability, and personality changes. -Megaloblastic madness: delusions, hallucinations, outbursts, and paranoid schizophrenic ideation. -Identifying the cause is important because significant reversal of these symptoms and findings can occur with vitamin B-12 administration.

G6PD Deficiency -Triggers for Hemolysis

-Older cells are most affected. -A variety of drugs can cause oxidative damage to RBCs of patients with G6PD deficiency including sulfonamides, antimalarial drugs, and nitrofurantoins. -A variety of infections can also induce hemolysis.(viral hepatitis, pneumonia, typhoid fever) -Fava beans can also cause hemolysis because the legume generates oxidants which react with RBC membrane. -The hemolytic syndrome following fava bean ingestion is termed favism which may result in significant hemolysis. *Favism is endemic in the Middle East, Mediterranean, and parts of Africa.

G6PD Deficiency -Oxidative Damage

-Oxidative damage to the RBC causes denatured hemoglobin to precipitate out into the cell. -These particles of precipitated hemoglobin can be seen as dark blue inclusion bodies (called Heinz bodies) after staining with crystal violet or methylene blue.

Hemoglobin C Disease -S/Sxs:

-Patients with Hb CC develop anemia and become more symptomatic as anemia worsens. -Symptoms include: * abdominal pain * arthralgias * possible mild jaundice. -Unlike sickle cell anemia, look for SPLENIC ENLARGEMENT with Hb C disease.

Normal Absorption of B12

-Pepsin releases it from its protein bound form -Binds to salivary R Binders -In DUODENUM attached to IF -IF-B12 transported to ILEUM --> -ATTACHES TO ILEUM RECEPTORS --> -TRANSCOBALAMIN carrier take to LIVER 7 cells

Pernicious Anemia

-Pernicious anemia: Chronic illness dt impaired absorption of vitamin B-12 dt a LACK of INTRINSIC FACTOR (IF) in gastric secretions. -Pernicious anemia is associated with: * gastric atrophy * loss of IF production * a rare congenital autosomal recessive form in which IF production is lacking without gastric atrophy -The adult form of pernicious anemia is most prevalent among individuals of either Celtic (i.e. English, Irish, Scottish) or Scandinavian origin. -Occurrence - 10-20 cases per 100,000 per year.

Folate Deficiency -In Pregnancy -Birth complications -Fetal Development

-Pregnant women need increased amounts of folate for proper fetal development. -Premature birth and neural tube birth defects - dt folate deficiency prior to pregnancy -Increased risk for placentia previa noted in folate deficient women. * the placenta will detach from the lower part of the uterus as the cervix begins to open in preparation for labor. This can cause severe vaginal bleeding Newborn conditions of increased risk in babies born to a woman with folate deficiency: -Low birth weight -Spina bifida -Cleft lip -Cleft palate

Iron Deficiency Anemia -Cuases

-Probably the most common nutritional disorder in the world. -Iron balance is maintained by regulating the absorption of dietary iron. -Iron deficiency can result from: (1) dietary lack (2) impaired absorption (3) increased requirement (4) chronic blood loss

Red Blood Cells

-RBC function is to deliver oxygen to tissues. * deliver oxygen via hemoglobin, a complex molecule containing heme groups whose iron molecules temporarily link to oxygen molecules in the lungs and release them throughout the body. -RBCs consist of approx. 90% hemoglobin; the heme is what gives blood its red color. -Anemia - decreased amounts of RBCs , Hct, Hgb -Polycythemia - increased amounts of red blood cells Normal life span of most RBCs is 90 to 120 days.

Hemolytic Anemias

-RBCs are prematurely destroyed. -Anemias characterized by: 1) shortened RBC life span 2) Hgb breakdown products accumulate 3) marked increase in BM erythropoiesis

Folate Deficiency -Consequences

-Red cells in folate deficiency anemia are: * abnormally large in blood (megalocytes) * abnormally large in the bone marrow as megaloblasts -Multinucleated (Hypersegmented) neutrophils * often many more than the normal neutrophil nucleus, which has 3-4 lobes -Decreased folate levels in serum (<5 ng/mL) or RBC (< 225 ng/mL). -Elevated homocysteine (serum).

Aplastic Anemia -Pathophysiology

-Results from ACTIVATED T CELL suppression of STEM cell fxn * First the stem cells are altered antigenically by: + exposure to drugs + Infectious agents + environmental toxins * This evokes a cellular immune response where ACTIVATED T CELLS PRODUCE CYTOKINES (TNF and interferon-gamma ) THAT PREVENT NORMAL STEM CELL GROWTH and development. -Stem cell Abnormality is supported by the presence of karyotypic aberrations in many cases and occasional transformation of aplasia to myeloid neoplasms (myelodysplasia and acute myelogenous leukemia). -Some marrow insult causes genetic damage that limits proliferation and differentiative capacity of stem cells. If damage is extensive enough, aplastic anemia results.

Hematopoeisis -Stages of Human Development

-Stem cells - in the yolk sac at 3rd wk of fetal development. -At ~3 months - migrate to the developing liver. -At ~4 months of age - migration of blood islands from the yolk sac to the bone marrow occurs. -At BIRTH - ALL of the BONE MARROW IS ACTIVE in the production of blood cells. -At PUBERTY - active RBC production becomes isolated to SPECIFIC MARROW SITES. - > 18 yrs, RBC production: * vertebrae * ribs * sternum * skull * pelvis * proximal epiphyseal portions of the humerus and femur. -These are called red marrow -Inactive marrow sites undergo fatty degeneration.

The Thalassemia Syndromes

-Thalassemia -a number of different hemolytic syndromes with abnormal synthesis of globin chains. -Beta thalassemia = deficient synthesis of the beta chain(s). -Alpha thalassemia = deficient synthesis of the alpha chain(s). -Found in populations of Mediterranean descent mostly.

Beta Thalassemia Major -Anemia

-The anemia of beta thalassemia major is usually quite severe. -Symptoms usually arise after 5-6 months of age as Hgb F diminishes. -The majority of erythroblasts die in the bone marrow. -Repeated transfusions are needed which increases burden of systemic iron overload. * Iron chelation must be started to prevent secondary hemochromatosis. -The resultant anemia without transfusions causes marrow expansion dt tissue anoxia which in turn causes ^'d erythropoietin * this all leads to skeletal deformities. -Death usually occurs in childhood unless supported by transfusions. * Patients usually do not survive past the third decade. Image shows: : x-ray film of the skull showing new bone formation on the outer table, producing perpendicular radiations resembling a crew-cut.

Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency

-The best understood RBC enzyme deficiency is Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency. -Several hundred variants of this enzyme deficiency exist. -Glucose 6 phosphate dehydrogenase is an enzyme in the Hexose Monophosphate shunt. -The hexose monophosphate shunt: * ^'s reduced glutathione that normally protects hemoglobin and the red cell membrane from oxidation by oxygen radicals. -Defects in the shunt leads to inadequate protection against oxidation, resulting in oxidation and the precipitation of hemoglobin and in lysis of the RBC membrane, leading to hemolytic disease.

Hereditary Spherocytosis

-The characteristic clinical features of HS are: * anemia * splenomegaly * jaundice -There is a great variability in dz severity -Similarly to sickle cell anemia, individuals with HS may suffer aplastic crisis most commonly caused by parvovirus B19. -Early in the disease process, the bone marrow may partially compensate with increased erythropoiesis. -Over time, continued hemolysis will outpace marrow's ability to compensate. -Gallstones common (~40-50% of HS patients.). -Recurrent hemolysis leads to enlargement of the spleen. -As the spleen enlarges, increased sequestration and destruction of RBCs occurs. -Splenectomy can stabilize the process. -Pneumovax is given prior to surgery.

Hereditary Spherocytosis -How the mutation deforms the RBC

-The spheroidal shape results from diverse mutations weakening interactions involving alpha-spectrin, Beta-spectrin, ankyrin, band 4.2, or band 3. * Most common=ankyrin mutation -These all contribute to the normal biconcave shape of the red blood cell. -Regardless of which molecular defect it is, reduced membrane stability leads to loss of membrane fragments during exposure to shear stresses in circulation -Spherocytes lose the characteristic pallor center of normal RBCs.

Acute Blood Loss

-The volume of blood loss may be incompatible with life. -If a patient survives the loss of blood, volume is rapidly restored by the shift of water from the interstitial fluid compartment. Hemodilution lowers the hematocrit - decreased in oxygenation of tissues triggers the pdn of erythropoietin (EPO) * dt decreased oxygenation of the renal juxtaglomerular JGA cells -BM responds by increasing erythropoiesis. -The bone marrow has the capacity to increase red blood production ~7-8 fold above baseline levels. -Internal blood loss allows for "recycling" of the Fe contained in the blood. -External blood loss: no recycling- depends on iron stores -Immediately after acute blood loss - peripheral smear usually appears normal * normal size --> normocytic * normal color --> normochromic -As marrow replaces lost RBCs: immature RBCs (Reticulocytes) appear in the PB

Alpha Thalassemia -Genetics -Alpha Thal Carrier -Alpha Thal Minor

-There are four genes that code for each of the alpha globin chains. -There are 4 separate variations of alpha thalassemia, dependent on the number of genes involved. -Silent Carrier State: deletion of only one gene will not result in any clinical signs and these patients are asymptomatic carriers. -Deletion of two of the four genes results in the condition known as alpha thalassemia minor or alpha thalassemia trait. -The symptoms of alpha thalassemia minor are identical to beta thalassemia minor, that is, minimal to no anemia.

Folate -Symptoms

-Unlike B-12 deficiency, folate deficient patients do NOT exhibit the neurologic complications associated with myelin loss in nerves of the posterior column. -However, a patient with combined B-12 and folic acid deficiency who has had folic acid replacement may have a normal appearing peripheral blood smear, thus potentially masking the diagnosis.

Hereditary Spherocytosis

-a genetic disorder of the RBC's membrane that can cause anemia, jaundice (yellow-tinged skin), and enlargement of the spleen. -The RBCs have a smaller surface area than normal red blood cells, which can cause them to break open easily. -A family history increases the risk for this disorder, which is most common in people of northern European descent but can affect all races.

Sickle cell anemia

-a severe form of anemia found most commonly in people of African heritage, although it can affect those of Caucasian, Saudi Arabian, Indian, and Mediterranean descent. -In this condition, the hemoglobin forms long rods when it gives up its oxygen, stretching red blood cells into abnormal sickle shapes. -This leads to premature destruction of RBCs, chronically low levels of hemoglobin, and recurring episodes of pain, as well as problems that can affect virtually every other organ system in the body. -About 1 out of every 625 African-American children is born with this form of anemia.

Beta Thalassemia Minor -Anemia

-hypochromic -microcytic * resulting in small, pale cells similar to iron deficiency anemia. -There can also be ↑ RBC's on CBC.

Iron Deficiency Anemia -Histology

-microcytic, hypochromic RBCs with a central zone of pallor -poikilocytosis in the form of small, elongated red cells also called pencil, cigar cells, or elliptocytes -BM shows mild-moderate ^ in erythroid progenitors (normoblasts). -Disappearance of stainable iron from mononuclear phagocytic cells in the marrow is diagnostically significant.

Iron Deficiency Anemia -cells size, Hgb -Clinical Presentation

-microcytic, hypochromic anemia. Anemia only appears when: * Iron stores are completely depleted * Low serum iron * Low serum ferritin * Low transferrin saturation Clinical presentation includes: * koilonchia (nails thin and concave) * alopecia (hair loss) * atrophic changes in the tongue and gastric mucosa, and intestinal malabsorption. Picture: Note the small red cells containing a narrow rim of peripheral hemoglobin. Scattered fully hemoglobinized cells, present due to recent blood transfusion, stand in contrast.

* Glucose-6-phosphate dehydrogenase (G6PD) deficiency

-most commonly affects males of African heritage. -RBCs either do not make enough of the enzyme G6PD or the enzyme that is produced is abnormal and doesn't work well. -When someone born with this deficiency has an infection, takes certain medicines, or is exposed to specific substances, the body's RBCs suffer extra stress. -Without adequate G6PD to protect them, many red blood cells are destroyed prematurely.

Beta Thalassemia

-the most common cause of beta thalassemia. -Both globin genes are present in the cell, but fail to produce hemoglobin adequately * (This contrasts with alpha thalassemia, in which one or more of the genes is actually missing from the cell). -If one of the beta globin genes fails the amount of beta globin in the cell is reduced by half. * This is called thalassemia trait or thalassemia minor. -If both genes fail, no beta globin protein is produced. * This is called beta thalassemia MAJOR.

Thalassemia

-usually affects people of Mediterranean, African, and Southeast Asian descent -is marked by abnormal and short-lived RBCs. -Thalassemia major, also called Cooley's anemia, is a severe form of anemia in which RBCs are rapidly destroyed and iron is deposited in the skin and vital organs. -Thalassemia minor involves only mild anemia and minimal red blood cell changes.

Microcytic Hypochromic Anemias

1. Iron deficiency 2. Lead poisoning 3. Thalassemia 4. HypOthyroidism 5. Anemia of chronic disease

Folate Deficiency -3 Major Causes

3 major causes of deficiency: 1.) Decreased intake - inadequate diet or impaired intestinal absorption - In alcoholics with cirrhosis deficiency is dt trapping of folate within the liver, excessive urinary loss, disordered metabolism. - phenytoin/Dilantin and OC's interfere with metabolism. 2.) Increased requirements - pregnancy -infancy -hemolytic anemias -disseminated cancer. 3.) Impaired use - folic acid antagonists * ie; methotrexate (chemo rx)

Hemolytic Anemias - Extrinsic (extracorpscular)

=Abnormalities outside of the RBC Immunohemolytic Anemia: -Commonly referred to as autoimmune hemolytic anemias = AIHA -Classified by characteristics of the responsible Ab. (See chart in Text) -Dx requires detection of Abs &/or complement * Coombs & indirect Coombs antiglobulin to test

Pernicious Anemia -Association w/ other diseases

An association exists between pernicious anemia and other AI diseases: -(autoimmune thyroiditis , type I DM, ulcerative colitis, Addison disease, and acquired agammaglobulinemia). -An association btw pernicious anemia and Helicobacter pylori infections has been postulated but not clearly proven. -Patients with pernicious anemia have a 2 to 3 fold increased incidence of gastric carcinoma.

Hemoglobin

An iron protein- compound in red blood cells that gives blood its red colour and transports oxygen, carbon dioxide, and nitric oxide. It carries oxygen to body cells. After releasing oxygen to the body tissues, hemoglobin picks up carbon dioxide and transports it to the lungs, where it is exhaled. Hemoglobin also gathers and releases nitric oxide, which plays an important role in regulating blood pressure by relaxing the blood vessel walls. Hemoglobin controls the expansion and contraction of blood vessels by regulating the amount of nitric oxide in the vessels.Hemoglobin is contained entirely in the red blood cells. To combine properly with oxygen, red blood cells must contain adequate hemoglobin. Iron is needed for the formation of hemoglobin. A lack of hemoglobin caused by iron deficiency leads to anemia

Sickle Cell Morphology

Anatomic alterations are dt: -Chronic hemolysis -↑ formation of BILIRUBIN -Small vessel stasis and thrombosis. -BM is hyperplastic dt hyperplasia of erythroid progenitors. * See prominent cheekbones and changes in skull. -Splenic changes - enlargement in early phase of the disease. Eventual shrinkage dt hypoxia, thrombosis, infarction and fibrosis - autosplenectomy. -Pigmented gallstones - dt ↑ breakdown of hgb. and hyperbilirubinemia.

Anemia -Classification

Anemia can either be due to either: 1. Excessive blood turnover -Hemorrhage * blood loss outside of the vascular system -Hemolysis * RBC destruction within the body 2. Failure of blood production

Beta Thalassemia Major -Anemia by 2 Mechanisms

Anemia results by 2 mechanisms: -deficit in HbA synthesis produces "under-hemoglobinized," hypochromic, microcyctic RBCs with subnormal oxygen transport capacity. -diminished red cell survival and their precursors dt an imbalance in the alpha- and beta-chain synthesis. * The free alpha-chains form insoluble inclusions in the normoblasts causing cell membrane damage and apoptosis (cell death).

Aplastic Anemia -Peripheral Blood -Bone Marrow Morphology

Aplastic anemia is a BM failure syndrome characterized by: -PB Pancytopenia -BM hypOplasia Morphological Bone Marrow Picture: -the BM is largely devoid of hematopoietic elements -showing largely fat cells -fibrous stroma -scattered or clustered foci of lymphocytes and -plasma cells remain

Sickle Cell Anemia

Atrophy of the spleen causes -impairment of normal resistance to encapsulated organisms such as * Streptococcus * Haemophlus influenza * Salmonella. -Pneumococcal pneumonia infxns are more common * diminished in frequency/severity with Pneumovax vacx before spleen damage. -Salmonella osteomyelitis: * More common in sickle patients --> avascular necrosis(AVN) occurs

Blood Loss

Blood loss -Massive hemorrhage/Acute -Slow loss/chronic- G.I. Tract, Gyn or GU. -Symptoms vary with the degree of anemia & the rate of development of the anemia. -A rapid drop in hemoglobin is tolerated less well and is therefore more symptomatic then a similar decline in hemoglobin or RBC number over a longer period of time.

Hemolytic Anemias - Extrinsic -Resulting from RBC Trauma

Caused by: -cardiac prostheses -narrowing/obstruction of microvasculature. (DIC) Other causes: -SLE -malignant HTN -TTP -hemolytic-uremic syndrome HUS -cancer. -All are dt microvascular lesions--> mechanical injury to RBCs. -Peripheral smears show RBC fragments: * schistocytes, burr cells, helmet cells -TTP and HUS are the only conditions that cause major clinical problems assoc with hemolysis. -TTP = Thrombotic thrombocytopenic purpura -HUS and TTP= fall into the broader category of thrombotic microangiopathies (TMA). -TMA's are characterized by the involvement of widespread occlusive microvascular thromboses resulting in thrombocytopenia, microangiopathic hemolytic anemia, and variable signs and symptoms of end-organ ischemia.

Macrocytic Anemia -Cbl or Folate Deficiency

Cbl or folate deficiency: -Thymidine synthase function is impaired b/c Cbl and folate are coenzymes required for synthesis of thymidine. -This leads to megaloblastic changes in all rapidly dividing cells because DNA synthesis is diminished. -In erythroid precursors, macrocytosis and ineffective erythropoiesis occur.

Hemoglobin -Globin Synthesis

Chain structure Hemoglobin type Alpha2beta2 A1 97% Alpha2delta2 A2 2% Alpha2gamma2 F 1% Alpha2betaS2 S Alpha2betaC2 C Gamma4 Barts Beta4 H

Anemia -Causes

Characterized by low oxygen transport capacity of the blood due to: 1) blood loss 2) impaired RBC production 3) ^ RBC destruction 4) a combination of these alterations Examples include: -Blood loss -G6PD -Iron-deficiency anemia - Hereditary spherocytosis -Pernicious anemia -Thalassemia -Sickle-cell anemia

Chronic Blood Loss

Chronic blood loss causes anemia only IF 1) Rate of loss exceeds the capacity of the marrow to restore adequate numbers of RBCs 2) Iron stores are depleted such that inadequate hemoglobin is available. The cause of chronic hemorrhage usually involves a problem in the following organ systems: -Gastrointestinal tract * ulcer, colitis, cancer -Gynecologic * excessive menstrual flow, cancer -Genitourinary * cancer or stone

Sickle Cell Anemia -Clinical Manifestations

Clinical manifestations are dominated by: -chronic hemolysis and ischemic tissue damage resulting from occlusion of small blood vessels. Pathogenesis of microvascular occlusions: -No correlation bt. # of irreversibly sickled cells and freq. / sev. of ischemic episodes. -possible that reversibly sickled cells (rsc) initiate occlusion dt ↑ levels of adhesion molecules and are AbN sticky in certain assays. -This coupled with inflammation ↑ adherence of cells to endothelium. -Recent literature indicates that pts with sickle cell anemia have ↓ nitric oxide dt it's ↑ hgb (released from lysed RBC) that binds it. -This in turn ↑ vascular narrowing and platelet aggragation.

Anemia -Definition

Defined: 1. decreased # of total RBC mass 2. measured as a decreased volume of packed RBCs within the plasma = hematocrit 3. decreased concentration of hemoglobin in the blood

Iron Deficiency Anemia -Labs

Diagnosis is made with lab studies - the PB smear will have parameters previously discussed as well as: -Low serum ferritin (low storage) -Low iron levels (low circulating) -Elevated TIBC: * total plasma iron-binding capacity (holding on tight to what it has) -There is a documented circadian rhythm for serum iron levels &amp; TIBC but not for serum Ferritin! -TRANSFERRIN is NORMALLY only about 1/3 saturated with iron and there is a substantial unsaturated plasma iron binding capacity. -An unexpected influx of iron can be handled easily. -The iron binding capacity of serum is of clinical interest. It is accounted for almost entirely by transferrin. -There are three components to the iron binding capacity of serum. * Serum iron is the concentration of iron present. Normally it is about 100 micrograms of iron per 100 milliliters of blood. * Total iron binding capacity (TIBC) is the maximum amount of iron that can be bound. Normally this is about 300 micrograms per 100 milliliters. * The unsaturated iron binding capacity (UIBC) is the difference between the TIBC and the serum iron. It is normally about 200. Iron binding capacity is used in the DDX of certain diseases. + In conditions associated with increased need for iron (IDA or late pregnancy) TIBC is increased, but saturation is decreased from the normal 33%. + In hemochromatosis, TIBC is low, but it is saturated. + Certain other clinical conditions are associated with their own characteristic patterns of TIBC and percent saturation.

B-12 Deficiency -Diagnosis

Diagnostic features of B-12 deficiency include: -low serum B12 levels (<180pg/mL) or RBC (more reliable) vitamin B-12 level. -Low hgb, hct, and RBC counts -unless there is a concomitant iron deficiency anemia, the MCV is usually markedly elevated. wbc and platelet counts may be decreased. -increased serum homocysteine & methylmalonic acid levels * risk factor for atherosclerosis and thrombosis. -Mild jaundice dt ineffective erythropoiesis & hemolysis of RBC's -Inability to absorb oral B12 supplementation.

Hemolytic Anemia -Extravascular Hemolysis

Extravascular hemolysis: -RBCs have structural changes = less deformable as they traverse the circulation. Examples of extravascular hemolysis include: -sickle cell anemia -hereditary spherocytosis (HS). Pictures: -Left: Sickle Cell Anemia -Right: Hereditary Spherocytosis

Folate Deficiency -Folate Uses -Folate Sources -Medications that interfere w/ absorption

Folate, folic acid (pteroylmonoglutamic acid), - necessary for RBC formation and growth. Sources: -green leafy vegetables (folage) -certain fruits (lemons, bananas, melons) -yeast -liver. Medications interfere with the absorption: -Dilantin * intefeferes with DNA synthesis at Deoxyribotide formation -oral contraceptives (OC) -Folate is NOT stored in the body in large amounts, a continual dietary supply of this vitamin is needed.

Hemolytic Anemias -Intrinsic vs. Extrinsic

Hemolytic anemias - classified as either intrinsic or extrinsic. Intrinsic hemolytic anemias include the genetic & hereditary RBC diseases. Genetic conditions include: -disorders of the RBC membrane -RBC enzyme deficiencies -disorders of hemoglobin synthesis Extrinsic anemias - Conditions in which the abnormality is outside of or extrinsic to the RBC itself. Extrinsic causes include: -heart valve prosthesis and A-V shunts -infections such as malaria -chemical injury such as lead poisoning, snake venom -abnormal sequestration of the RBCs in the spleen (hypersplenism) -acquired hemolytic anemias

Anemia of Chronic Disease -Anemia characteristics -Labs

HypOproliferative anemia: -RBC BM precursors are deficient in their iron uptake and utilization. ACD [Unlike IDA] is characterized by: -Low iron levels AND Low TIBC -With Normal or even Elevated ferritin levels * Patient has ENOUGH STORED Iron - they're just not using it corrently ACD generally presents as: - Normocytic-Normochromic anemia -in 1/3rd it presents as Micro-Hypochromic indicating progressive ACD dz associated WITH IDA (low ferritin, low iron, ^ TIBC)

Sickle Cell Pathophysiology

Image shows: -Sickled cells causing congestion in the spleenic sinuses * may or may not lead to an infarction -Increased hemolysis of RBCs b/c they're sickled * resulting in ^ bilirubin -Microvascular occlusion by sickle cells dt: * inflammation in the vessels, causing narrowing and reduced flow * membrane changes causing ^'d adhesiveness

Iron Deficiency Anemia -Impaired Absorption

Impaired absorption is found in: -celiac dz and sprue -other czs of intestinal steatorrhea * a SYMPTOM in which fecal matter is frothy, foul-smelling and floats because of a high fat -chronic diarrhea -Gastrectomy: * Decreased Fe absorption dt decreased HCL and transit time through the duodenum. Dietary substances that inhibit absorption of nonheme Fe are: -phytates * (hulls of nuts, seeds, cereals, soy) -Tannates * (black tea, bark & fruit of many plants) -phosphates * soft drinks?

Iron Deficiency Anemia -Increased Requirement

Increased requirement in: -growing infants -children -adolescents -menstruating women -pregnant women -Women of low socioeconomic status having multiple, frequent pregnancies are at higher risk.

Sickle Cell Anemia -Complications

Potential vaso-occlusive complications include: -retinal infarctions -leg ulcers -priapism -painful bone infarctions "Chest syndrome" is a group of Sxs: -chest pain -Fever -Leukocytosis -lung infiltrates & potential pulmonary infarction.

Folate Deficiency -Risk Factors -Incidence

Risk factors are: -a poor diet * (seen frequently in the poor, elderly, and in people who do not eat fresh fruits/vegetables) -overcooking food -alcoholism -a history of malabsorption disease -pregnancy Rx: - Lithium -In the U.S., folate deficiency occurs in ~4 out of 100,000 people.

Sickle Cell Spleen Histology -Low Power

Spleen in sickle cell anemia (low power). -Red pulp cords and sinusoids are markedly congested -between the congested areas, pale areas of fibrosis resulting from ischemic damage are evident.

Hereditary Spherocytosis -Diagnosis

The diagnosis of hereditary spherocytosis is based on: -family history -hematological evidence -testing of RBC fragility Test: -RBCs are placed in a hypotonic salt solution which results in lysis of the cells because there is little margin for cell expansion of RBC volume without rupture.

Sickle Cell Spleen Histology -High Power

Under high power, splenic sinusoids are dilated and filled with sickled red cells.

Reticulocytes

What is polychromasia? -Normal lab value range for Reticulocytes- 0.5-1.5% of circulating red blood cells -After an acute bleed, the reticulocyte count may climb to 10 - 15% within a week of the acute event. -Reticulocytes are usually larger then mature RBCs and exhibit polychromasia

Anemia -Sxs

With signifigant anemia of any cause, the patient may exhibit the following sxs: -pallor -increased pulse rate and weakness of pulse -shortness of breath (SOB) -palpitations -dizziness -fatigue -headaches -faintness or syncope

Megaloblastic (Macrocytic) Anemias

most common causes: -B-12 deficiency -Folic acid deficiency -Hyperthryoidism (dt increased requirement) -pregnancy (dt increased requirement) -disseminated cancer (dt increased requirement) -Inadequate diet (TPN, B12) -alcoholism -Impaired DNA synthesis and distinctive morphological changes in the blood and bone marrow are keynotes. * SYNTHESIS of RNA is UNAFFECTED so CYTOPLASM enlargement is not matched by DNA synthesis. * ASYNCHRONOUS development