Perioperative Blood Management Final Exam Materials
Describe neutrophils.
- 1st line of defense to fight infections - 12-15 microns in diameter - 2-5 lobe nucleus - Primary or secondary granules - Lifespan of 10 hours - 50-70% of mature granulocytes are called segmented neutrophils - Bands and Segments - Mature neutrophils 2x the size of erythrocytes - Does not return in blood --> turns into pus and dies - Mechanism: --Ferocious eaters --Secretes products to attract monocytes --Generates NETs (neutrophil extracellular traps)
What is heparin induced thrombocytopenia (HIT)? What are the two types, and what is its most common cause?
- Decreased platelet count following heparin therapy • <150,000 platelets/µL • Up to 50% decrease from baseline • Onset may be rapid or delayed • Mechanism of response o Binds to platelet factor 4 (PF4) o IgG, IgM and IgA antibodies generated o Aggregates are prematurely removed from circulation o Platelet activation leads to prothrombotic platelet microparticles --> coagulation - (2) types • Type I o Presents within 2 days of exposure o Platelet count slowly normalizes o 'Relatively' benign • Type II o Immune-mediated o Occurs 4-10 days after exposure o Life and limb threatening consequences - Most common cause unfractionated heparin (unfractionated, meaning sizes vary—useful for increased activated coagulation time. • Not as much platelet factor activity within LMWH (low molecular weight heparin)
Describe eosinophils.
- Large and round with uniform granules. - Normally about 0-4% of blood. - 2-4 lobed nucleus - Destruction of tumor cells
Describe basophils.
- Only constitute 0-2% of normal blood cells. - Vary in size: 0.2-1 microns - Water soluble: does not mix well when stained - 1-2 lobed nucleus - Releases histamine - Helps release prostaglandin
What is the diameter of basophils?
0.2-1 microns
Describe the 6 events leading to platelet plug formation.
1. Vasoconstriction - regulates blood flow in a damaged cell, assists in adhesion (involves vWF) 2. Platelet shape change - interaction of circulating platelets and agonists such as ADP, collagen, thrombi and thromboxane 2 alter the cytosolic calcium and change the shape of the platelet. Both TXA2 and ADP bind to the membrane receptor surface and expose it to platelet membrane phospholipids which cause aggregation. 3. Platelet aggregation - platelet to platelet interaction mediated by fibrinogen, calcium and platelet membrane activated glycoprotein IIb/IIIa. Usually begins 10-20 seconds after vascular injury and platelet adhesion. Requires ATP. Fibrinogen binds to activated platelet membrane GPIIb/IIIa complex and calcium/fibrinogen bridges form and promote platelet aggregation. 4. Platelet plug 5. Platelet secretion - Release of granule contents amplifies platelet response, liberated ADP and calcium from the dense granules. Release of ADP makes other platelets sticky--stickiness of platelets causes them to adhere to the originally activated platelets. Serotonin and thromboxane A2 function as vasoconstrictors--contracts vascular smooth muscle and decreases blood flow through the injured vessel. 6. Stabilization - Last stage in arresting bleeding. Activation of coagulation cascade and formation/deposit of fibrin on the platelet aggregates. Fibrin interweaves through the initial platelet, compressing into place at the site of injury.
What is the lifespan of neutrophils?
10 hours
What is the lifespan of monocytes?
12 hours
What is the diameter of neutrophils?
12-15 microns
What is normal Hgb for adult females?
12.1-15.1
What is the diameter of monocytes?
13-15 microns
What is normal Hgb for adult males?
13.8-17.2
What is normal Hgb for newborns?
14-24
What are the formed elements of the blood, and what are their relative abundances?
150-400 thousand platelets/microliter 4.5-10 thousand white blood cells/microliter 4.2-6.2 million red blood cells
What is the diameter of platelets?
2-4 microns
What, in general, are the characteristics of platelets?
2-4um in diameter, 150-400 thousand in the body Originate in bone marrow Develop 5-7 days after release of thrombopoietin 70% of all platelets are present in circulation with 30% in microvasculature of the spleen (reserves) Survive 7-10 days in circulation and are "active" for hemostasis Increases number and rate of maturation of megakaryocytes. Need platelet count >50,000 for adequate hemostasis.
What is normal HCT for infants?
28.5-39%
What is normal HCT for adult females?
36.3-45.3%
What is normal HCT for adult males?
41.4-51.6%
What is normal HCT for newborns?
42-72%
What are the components of whole blood?
55% plasma 45% formed cells
What is the relative composition of plasma?
7% proteins - albumins, globulins, and fibrinogen 91% water 2% ions, nutrients, waste products, gases and regulatory substances
What is the lifespan of platelets?
7-10 days
What is the diameter of lymphocytes?
7-10 microns
What is normal Hgb for infants?
9.5-13
How many platelets are needed for adequate hemostasis?
>50,000
What is commonly given as an alternative to heparin?
A direct thrombin inhibitor (DTI), like argatroban, lepirudin, or bivalirudin
What is von Willebrand's factor?
A plasma protein released by damaged endothelial cells that links the platelet to the subendothelial binding sites.
What is the fibrinolytic system?
Activation of coagulation also activates the fibrinolytic system--re-establishes blood flow in vessels from thrombus and facilitates healing. Plasmin is generated by inactive plasminogen, which is activated by t-PA. Plasmin - has a strong affinity for fibrin; cannot distinguish between fibrinogen and fibrin. Cleaves the x fragment to y fragments and results in D and E fragments of fibrin, fibrin degradation products (fibrin split products)
Describe, in general, the process of hematopoiesis.
All cellular blood components are derived from hematopoietic stem cells (HSCs, 10^11 - 10^12 produced daily), which have the ability to give rise to all different types of mature blood cells and tissues. HSCs reside in the medulla of bone or bone marrow and are self-renewing. 3 lineages are developed among HSCs - erythroid (RBC), lymphocytes (adaptive immune system, T/B lymphocytes), and myelocytes (granulocytes).
Describe the intrinsic pathway of coagulation.
All the factors necessary for clot formation are intrinsic to the vascular compartment because they are all found within the circulating blood. The phospholipids required in the intrinsic pathway are provided by the platelet membrane. Following exposure to negatively charged foreign substances or activation of factor XII involving contact factors, the pathway is initiated. Factors required: VIII, IX, XI, XII, prekallikrein and HMWK, calcium and PF3 Factor IX activated by factor XIa in presence of calcium; activated IXa along with VIIIa (with calcium and PF3) activate X to Xa.
What is hemophilia A?
An X-linked recessive chromosomal hemophilia.
Define anisocytosis and poikilocytosis.
Anisocytosis - varying RBC sizes Poikilocytosis - varying abnormal shapes
What are the natural anticoagulants in the blood?
Antithrombin III (ATIII) prevents prothrombin from becoming thrombin - main physiologic inhibitor of thrombin and factors Xa, IXa, XIa and XIIa; activates protein C and kallikrein; in presence of heparin, ATIII is consumed and inhibits thrombin Protein C (also kind of protein S) - activated by thrombin and the endothelial cell thrombomodulin; the complex of thrombin/thrombomodulin accelerates activation of protein C. Activated protein C exerts an anticoagulant effect by inactivating factors Va and VIIIa and slowing thrombin formation.
Describe iron and its available forms in the body.
Average adult content: 3500-4000mg. 2/3 of this is present in hemoglobin and the last 1/3 is present as tissue iron (in the bone marrow, liver and spleen). 90% of total tissue iron is stored and available in the form of Ferritin (mobilized in the body and easily utilized--Fe3+ in serum and tissue sites for iron storage) or Hemosiderin (produced from aggregates of ferritin and less available for utilization--Fe3+ in bone marrow and tissue sites for iron storage).
What is hemostasis?
Balance between thrombosis and bleeding. Represents a delicate balance between procoagulant and anticoagulant mechanisms allied to fibrinolysis. A complex process that maintains blood in the fluid state within the vascular compartment. Regulated and highly integrated interactions--eventually all bleeding stops (for better or worse)
What are the characteristics of a red blood cell?
Biconcave in shape--increases surface area for oxygen to bind to the erythrocyte. No nucleus. 7-8 microns (or micrometers) in diameter 1.5-2.5 microns (or micrometers) in thickness Volume of ~90 fL (cubic micrometer or cubic micron, 10^-15 L) Central portion is the thinnest Uniform in size 120 day lifespan Eventually rupture in the spleen
Why is blood classified as a non-Newtonian fluid? What even is a non-Newtonian fluid?
Blood is classified as a non-Newtonian fluid due to its viscosity (measured in millipoise, representing dynamic velocity) - normally 40/100. A non-Newtonian fluid is identified as a fluid whose viscosity is variable based on applied stresses or forces, i.e. a fluid whose movement is affected by the movement of elements dissolved/contained within.
What are the major components of hemostasis?
Blood vessels Platelets Coagulation proteins Fibrinolysis Serine Protease Inhibitors (can intiate clot/inflammatory response)
Define thrombocytosis
Bone marrow overproduces megakaryocytes (cause still largely unknown) >400,000 May be related to anemia, low iron concentration (stem cells not differentiating to platelet), MI, infections, chronic kidney failure, splenectomy, trauma/burns
What composes the hematopoiesis system of the body?
Bone marrow, liver, spleen, lymph nodes, thymus. In adults, bone marrow of the sternum, ribs, pelvis and vertebrae primarily. From infancy to childhood, primarily takes place in marrow of long bones. During gestation, takes place primarily in the yok sac (2 months->), liver (2-7 months), spleen (2-7 months), axial and radial bones (late stages of fetus and after birth--fat begins to form in long bones at 4 years of age).
Give some examples of quantitative platelet disorders.
Can take place with: - Deficient platelet production - Ineffective erythropoiesis - Congenital disorders - Abnormal distribution of platelets - Increased destruction
What are the role of interleukins?
Cause stem cells to produce precursors to mature blood cells; respond to tissue injury and foreign matter in the inflammatory response. IL-3, for example, is vital to normal hemopoiesis.
In general, how does the blood function with regard to protection?
Clotting mechanism (coagulation) and immunity against infection.
Describe the process of secondary hemostasis.
Coagulation cascade system. The platelet plug is reinforced by the secondary hemostasis system to produce the fibrin clot formation. The system is mediated through coagulation proteins (coagulation factors) that become activated Roman Numerals (according to sequence of discovery). Some factors referred to as common name such as fibrinogen or prothrombin. Activation of factor is denoted by a small "a" next to roman numeral (Xa). All coagulation factors are produced in the liver.
What can cause qualitative platelet disorders?
Congenital defects. 3 classes: Platelet surface membrane defects • Glanzmann's thrombasthenia - absence of GPIIb/IIa complex Platelet release or secretion defects • Glycoprotein release of granules that cause change of shape and aggregation - defect in COX pathway Abnormal platelet coagulant proteins
Give some examples of qualitative platelet disorders.
Congenital disorders of platelet function Von Willebrand disease Acquired platelet disorder
What do the Mean Corpuscular Hemoglobin (MCH) and Mean Corpuscular Hemoglobin Concentration (MCHC) measure?
Content of Hgb in the RBC. MCH = Hgb x 10 / RBC count (DON'T NEED TO CALCULATE/MEMORIZE THIS FORMULA) - Weight of Hgb in RBCs MCHC = Hgb x 100 / HCT = % (DON'T NEED TO CALCULATE/MEMORIZE THIS FORMULA) - % Hgb in RBC
How does the vascular system prevent bleeding?
Contracts vessels (vasoconstriction) at site of damage, diverts blood flow around damaged vasculature, initiates contact activation of platelets and contact activation of coagulation system
What is the structure/function of the Sol-Gel zone of the platelet?
Cytoskeleton of the platelet Consists of microtubules to maintain the discoid shape Microfilaments - composed of contractile proteins actin and myosin, once microtubule changes shape microfilaments can contract sub-membranous filaments
Define thrombocytopenia.
Deficient platelet production/abnormal platelet distribution/increased destruction. <100,000 Overt bleeding with count <20,000 <10,000 is life threatening
Describe megakaryocytopoiesis and megakaryocytes.
Descending from HSC's (signaled by thrombopoietin or erythropoietin*) form: Megakaryoblasts - MKI - 10-15 micron diameter Promegakaryocyte - MKII - Enlarges to 80 microns - Granules formed into Golgi Megakaryocyte - MKIII - Basophilic megakaryocyte - Glycogen stores -> sustain platelets for 9-11 days Megakaryocyte - MKIV - Final stages of maturation - Releases cytoplasmic fragments (platelets) through marrow sinusoid fenestrations -> budding or shedding platelets - Once platelets are released the naked nuclei are phagocytized by marrow histocytes. * This wasn't in the PPT's, I got it from Wikipedia
In general, how does the blood function with regard to regulation?
Electrolyte balance and regulation of pH.
What does the Mean Corpuscular Volume (MCV) measure?
Estimated size of RBC in femoliter (fL - 1 cubic micrometer). MCV = HCT x 10 / RBC count (DON'T NEED TO CALCULATE/MEMORIZE THIS FORMULA)
What is a blood smear (or blood film) and why is it performed?
Examines the morphology of blood and indicates % of each cell type present. Fixated with methanol (essential for good staining and cellular detail) and stained with Romanowsky, Wright's or Giemsa to detect WBC's, RBC's and platelet abnormalities. Viewed under 1000x magnification.
What causes iron overload? How can we treat it?
Excessive accumulation of iron to supernormal levels. Increased hemosiderin deposits in liver, spleen and bone marrow--no physiologic mechanism for elimination of excess iron. 4 stages - 3rd and 4th stages result in organ damage and cirrhosis. Caused by increased iron absorption or transfusion overload. Diagnosis via serum iron and transferrin levels. Treated via iron chelation therapy.
Describe the common pathway of coagulation.
Factors X, V, II, and I Xa in presence of calcium and phosphate (PF3) Convert prothrombin (factor II) to IIa thrombin (active form, activates factors VIII and V which converts fibrinogen/factor I to fibrin). Factor XIII fibrin stabilizing factor --> XIIIa creates the fibrin polymer.
What is the structure/function of the peripheral zone of the platelet?
Glycocalyx - amorphous exterior coat Platelet membrane Open canicular system (OCS) Sub-membranous region Contains the platelet membrane: phospholipid plasma membrane, exterior glycoprotein coat Platelet membrane receptor reacts with GP1B, vWF, and collagen. Adhesion takes place with release of ADP and ATP from platelet granules--changes platelet shape and increases aggregation. Fibrinogen 10-20 seconds after vascular injury.
What are colony stimulating factors, and what are their roles?
Glycoproteins that promote production of white blood cells (mainly granulocytes) in response to an infection. Bind to the receptor proteins of hemopoietic cells.
What are the WHO grades of anemia?
Grade 0: >11.0g/dL Grade 1 (mild): 9.5-10.9g/dL Grade 2 (moderate): 8.0-9.4g/dL Grade 3 (serious/severe): 6.5-7.9g/dL Grade 4 (life threatening): <6.5g/dL
How is HCT calculated?
HCT = MCV x RBC count
What is hemolytic anemia?
Hemolysis resulting in decreased RBC counts. Hemolysis - increased destruction of RBCs, shortened life span, decreased tissue oxygenation and increased erythropoietin, increased reticulocytes Acute vs. chronic - rapid onset (transfusion reaction) vs. chronic illness Inherited vs. acquired Intrinsic vs. extrinsic - RBC defects (membranes, enzymes) vs. RBC-external factors (antibodies, heart valves, etc.)
What are the normal values for Hgb, HCT, WBC's, and platelets?
Hgb normal values*: -> 13.8-17.2g/dL (adult male) -> 12.1-15.1g/dL (adult female) -> 14-24g/dL (newborn) -> 9.5-13g/dL (infant) HCT normal values*: -> 41.4-51.6% (adult male) -> 36.3-45.3% (adult female) -> 42-72% (newborn) -> 28.5-39% (infant) WBC's*: 4.5-10 thousand per microliter Platelets*: 150-400 thousand per microliter *Depends on choice of reference
What are some complications of HIT?
High risk for thrombosis causing significant morbidity and mortality 30-50% patients with HIT will have thrombotic complication within 30 days (DVT, PE, infarction, MI, spinal arteries) Venous and arterial thrombus is associated with a mortality rate of 20% 20-30% of patients will be permanently disabled... amputation chance in 20%
What causes hypochromic anemia?
Increased demands for iron (nutrition/malabsorption), abnormal utilization, increased blood loss.
Describe the extrinsic pathway of coagulation.
Initiated when factor III, not normally found in blood, enters the vascular system. Includes a phospholipid component that is the source for various factor interaction. The term extrinsic is used because the pathway is initiated by factors external to the vascular system. Factor III (tissue factor) includes a phospholipid surface for contatct. Factor III released from injured vessel wall. Factor VII is activated to VIIa in the presence of calcium (factor IV) and tissue factor (factor III) Only VIIa, calcium and factor III are needed to activate factor X to Xa.
What are 3 key components to forming red blood cells?
Iron, globin protein chains, and protoporphyrin (combines with iron and heme and is responsible for binding oxygen and carbon dioxide)
What are the various methods of Hgb/HCT measurement?
Manual RBC counting (dilution pipettes, not commonly used) Manual Hgb and HCT (MicroHCT method) Electrical Impedance Light scatter (co-oximetry)
Describe von Willebrand disease.
Most common inherited bleeding disorder - autosomal dominant inheritance pattern Caused from a lack of vWF 1% of general population • Occurs equally in men and women • First described in 1926 by Dr. von Willebrand in Finland - five-year-old girl with bleeding disorder located on chromosome 12 There is a decrease in factor VIII and an abnormal hemostasis Inherited deficiency of vWF • Autosomal dominant on chromosome 12 • Can appear as platelet defect Not the same as Hemophilia A • X-linked chromosome recessive gene Circulating vWF forms a complex with factor VIII, the protein that is deficient or defective in hemophilia A vWF acts as a carrier protein for VIII serving to protect the factor from proteolytic degradation and increase its concentration at the site of tissue injury Normal should have same levels of vWF and factor VIII Type 1 • Autosomal-dominant disorder • 70% of all cases • Decrease in normal vWF and possible low levels of factor VIII • Mild bleeding Type 2 • Variable inheritance with numerous subtypes • Makes normal amounts of vWF, but does not work properly • Qualitative abnormality in the structure of vWF • 4 sub-types Type 3 • Rare autosomal-recessive disorder • Characterized by absent vWF and little to no factor VIII • Severe disorders - usually life-threatening
Which cells compose white blood cells in the body? What percentage of total white blood cells do they represent?
Neutrophils: 60-70% Lymphocytes: 20-25% Monocytes: 3-8% Eosinophils: 2-4% Basophils: 0.5-1%
Describe iron metabolism.
Normal people lose about 37-42mL/day--2mL of blood contains 1mg of iron. 20mg of iron needed for each day for replenishment--shedding and sweating: 1mg, menses: 1-2mg. The majority of iron is heavily recycled. Daily dietary requirements are 1-2mg/day, with ferric iron being the most common dietary form.
What are the RBC indices, and what are their possible causes?
Normocytic (80-100 MCV) Normochromic (32-36% MCHC) Macrocytic (>100 MCV) Microcytic (<80 MCV) Hypochromic (<32% MCHC) See attached picture for possible causes.
Describe monopoiesis and monocytes.
Originating in the bone marrow from a common HSC, differentiation occurs to myeloid and then to monocyte stages via macrophage stimulating factor. Monocytes: - 13-15 microns in diameter - Large nucleus with 1-2 nucleoli - Basophilic cytoplasm (no granules) - Migrate into tissues and become macrophages which ingest and kill bacteria - 12 hour lifespan Monocytes are responsible for ingesting and killing bacteria.
What the 3 zones of the platelet?
Peripheral Zone, Sol-Gel Zone, and Organelle Zone
Describe Vitaimin B12 deficiency.
Pernicious anemia - atrophy of gastric parietal cell mucosa (decreased secretion of intrinsic factor, which is essential for B12 absorption). Lab test - serum B12, normally 200-500ng/L. Gastric achlorhydria. Antibodies to intrinsic factor. Schilling test (absorption of B12 from intestinal tract). Serum and urine homocysteine. Treated by B12 injections (bypassing need for intrinsic factor) and vitamin therapy.
What are some vascular disorders that can occur?
Primary and secondary bleeding from small blood vessels, congenital connective tissue disorders
What are the stages of hemostasis?
Primary hemostasis (platelet adhesion to exposed collagen within the endothelium of the vessel wall, 'platelet plug'), secondary hemostasis (enzyme activation of the coagulation proteins to produce fibrin), fibrinolysis (clot dissolves, plasmin digests fibrinogen and fibrin)
How is iron reuptake performed in the body?
RBCs broken down by the RES and iron released from Hgb and back into plasma. Also via transferrin.
How is iron absorbed in the body?
Regulated by the intestine--GI tract mucosal cells limit absorption. Amount of absorption determined by gastric acidity, pancreatic secretion, bone marrow activity, and state of intestinal mucosa. Converted into ferrous state (Fe2+)
What is the structure/function of the organelle zone of the platelet?
Responsible for metabolic activity--mitochondria and cytoplasmic granules. 3 storage granules: - Dense granules - store ADP, ATP, ionic calcium, serotonin, and phosphate - Alpha granules - most numerous, beta-thromboglobulin and platelet factor IV (both inhibit heparin), thrombospondin (promotes platelet interaction), platelet-derived growth factor, and factor V - Lysosomes - contain neutral protease, acid hydrolase, and bacteriocidal enzymes
Differentiate between reticulocytes and erythrocytes.
Reticulocytes appear blue in Romanowsky stains; if you have increased reticulocyte concentration it indicates that your body is having increased demand for RBC production (conditions like anemia). Low counts can tell us that erythrocyte production is being halted/stagnated.
How is iron stored in the body?
Reticuloendothelial cells of bone marrow, liver, and spleen. Stored in 2 forms: ferritin and hemosiderin.
Describe the release of erythropoietin (EPO)--where, why and how?
Secreted by the kidneys in response to cellular hypoxia; stimulates RBC production (erythropoiesis) in the bone marrow. Secreted from the tip of the juxtamedullary region of the cortex (10% also released from the liver). A release is delivered to the bone marrow where it signals growth factors to release stem cells for RBC formation. Once the central sinus of the medullary marrow is triggered, takes about 5 days to develop a mature erythrocyte.
What are the assays used to diagnose HIT?
Solid-phase immunoassays - heparin/PF4 enzyme-linked ELISA and particle gel immunoassays Functional assays - Heparin-induced platelet aggregation assay (HIPA), Serotonin release assay (SRA)
In general, how does the blood function with regard to transportation?
Solutes can be free in plasma, bound to plasma proteins, or bound to blood cells (nutrients from the GI tract to body cells, oxygen from lungs to tissues, carbon dioxide from tissues to lungs, hormones from endocrine gland to body cells, heat to regulate body temperature, and waste products away from tissues).
Describe lymphopoiesis and lymphocytes.
The generation of lymphocytes; lymphoid progenitor cell derives from common HSC and differentiates to T cell in the thymus, B cell in adult bone marrow, and natural killer cells/antibodies. Lymphocytes: - After neutrophils, the second most numerous cell in the blood (20-44% of adult white blood cells) - 7-10 microns in diameter - Most do not have granules - Large nucleus Produce antibodies and provide direct cytotoxic activity.
Describe the production (and storage) of mature cells once they are made.
The stem cell decides which factor it will become: myeloid or lymphoid progenitor? Interleukin helps it decide. WBCs stay in dormant form until they increase in response to external threat. Stem cells are stored in the bone marrow pool--when something acute occurs it can respond right away by releasing stem cells. The transition to its various products can take a while--for example, RBCs take about 5 days. In some cases, such as granulocytes and thrombocytes, these cells are stored--platelets in the spleen and WBCs in the various glands, etc.
How is iron transported in the body?
Transferred from mucosal cells to tissues via transferrin.
Describe alloimmune hemolysis.
Trigger is not the self; Transfusion - IgM, ABO incompatibility Pregnancy - hemolytic disease of newborn, immune RBCs destroyed by maternal alloantibodies (HDN), maternal-fetal blood group incompatibility Organ transplantation - antibodies produced against foreign antigen on the transplanted organ Acute vs. Delayed Hemolysis
Describe autoimmune hemolysis.
Trigger is the self; Body loses itself-->recognition of its own RBC antigens. Patients produce antibodies against its own RBCs. Warm type - most common, idiopathic. Cold type - cold agglutinins. Reactivity is at 4-22 degrees Celsius. Can react at or above 30 degrees Celsius. IgM activates complement. Hemolysis occurs from completion of the complement cascade. More likely to be seen during cardiopulmonary bypass--we run the pump cold.
Discuss the lab tests used to diagnose hemolytic anemia.
Unconjugated - indirect bilirubin, bound to albumin-->no GFR (jaundice) Serum haptoglobin - clearance of RES RBC destruction - hemoglobinemia (free Hgb liberation), hemoglobinuria (free Hgb attached to haptoglobin) Coombs test - tests for autoimmune hemolytic anemia; detects antibodies bound to RBC. After cell washing --> agglutination of RBCs Indirect Coombs test - used with prenatal testing to blood/blood transfusion. Detects antibodies present unbound in serum. Serum incubated with RBCs of known antigenicity.
How does the endothelium activate thrombus formation?
Upon injury to a vascular wall, platelets aggregate to the site. For every platelet bound, more platelets are attracted. Coagulation is activated resulting in thrombin secretion, converting fibrinogen to fibrin and fibrin polymers which secure RBCs to the site of the clot. Upon retraction, the clot breaks and fibrin fragments are released during fibrinolysis.
What is the CBC, and what are the 4 measures of the fishbone diagram?
WBC (leukocytes), RBC (erythrocytes), Mean Corpuscular Hemoglobin (MCH) - content of hemoglobinin the RBC, Mean Corpuscular Volume (MCV) - average size of RBC, MCH Concentration (MCHC) - content of Hgb in the RBC, Hematocrit (packed cell volume)
Describe folic acid deficiency.
Water soluble vitamin - 80% stored in the liver. Absorbed in duodenum and jejunum (80% intake). Necessary for the formation of thymidine for DNA synthesis. Most common causes: gluten sensitive enteropathy, infection causing intestinal atrophy, celiac disease. Treatment: folic acid vitamins given orally or temporally.
What is DDAVP? What are factor VII concentrates?
o DDAVP (desmopressin) - used primarily for vWD type 1 Synthetic replacement of vasopressin Stimulates release of vWF from the endothelial cells 0.3µg/kg IV over 15-30 minutes (pre-op) o Recombinant vWF/FVIII concentrates Approved in December 2015 Used in treatment of Hemophilia A, B, and von Willebrand's disease
Describe the functional assays used to diagnose HIT.
o Heparin-induced platelet aggregation assay (HIPA) Patient's serum is mixed with donor platelets in presence of heparin Activation indicates presence of antibodies to heparin-PRF complex Sensitivity 39-81%, specificity 82-100% o Serotonin release assay (SRA) Gold standard - high specificity (100%) and sensitivity (70-94%) Often performed off-site, can take up to 3 days Platelets are radiolabeled with carbon 14 serotonin and then mixed with serum with both low and high heparin doses • Positive = 20% serotonin release at therapeutic dosage of 0.1 U/mL heparin
Describe the solid-phase immunoassays used to diagnose HIT.
o Heparin/PF4 enzyme-linked ELISA and particle gel immunoassays o Pro: Widely available Rapid turn-around time High sensitivity (>99%) o Con: Poor specificity (30-70%) Also detect non-pathogenic antibodies
What does vitamin K deficiency have to do with coagulation? What factors are associated with vitamin K?
o Vitamin K is essential for coagulation factors II, VII, IX and X and the physiologic anticoagulants protein C and protein S Deficiency: • Inadequate supply • Dietary deficient • Destroyed by gut flora by administration of broad-spectrum antibiotics Impaired absorption of Vitamin K Biliary obstruction (gallstones, strictures, or tumors) Malabsorption of Vitamin K o Pharmacologic antagonists of Vitamin K include Coumadin
What is lupus anticoagulant?
• LA recognized in patients with SLE (Lupus) • Usually IgG or IgM • Interact with platelet membrane phospholipids (increase aggregation) • PT and PTT prolonged • Inhibit formation of prothrombinase complex (factors X, V, calcium and factor II) causing prolonged clotting
