Lab Heme/Coagulation Flashcards

Question

How is INR calculated?

Answer 1

INR = [Patient PT / Mean of normal PT range] ^ ISI. ISI = International Sensitivity Index for thromboplastin, used for PT determination. A patient with high ISI (ISI = ~2) will have low sensitivity to factor deficiencies. A patient with low ISI (ISI = ~1) will have high sensitivity to factor deficiencies.

Answer 2

If there is significant bleeding, discontinue warfarin, give vitamin K (most likely IV or sub-Q), and give plasma to replace the missing coagulation factors. If there is no significant bleeding, and there is a desire to regain the anticoagulated state as soon as possible OR the INR is less than 10, discontinue warfarin and allow INR to decline. If there is no significant bleeding, and there is no desire to regain the anticoagulated state as soon as possible OR the INR is greater than 10, discontinue warfarin and administer vitamin K (most likely oral).

Answer 3

Heparin is a very negatively charged compound, and protamine sulfate is a positively charged compound. They bind together and heparin is neutralized.

Answer 4

If it is LMWH used for prophylaxis or LMWH therapy in normal weight, normal renal function, non-pregnant patients, no monitoring is needed. If unfractionated heparin is used, target PTT to >2.0x mean of normal range (varies widely depending on reagents and instruments).

Answer 5

Allergic reactions (drug reactions, asthma), parasitic infections (strongyloidiasis), schistosomiasis, filariasis, toxocariasis), metabolic abnormalities (adrenal insufficiency), humoral immunodeficiency (hyperimmunoglobulin E syndrome (Job syndrome), Wiskott-Aldrich syndrome, hyperimmunoglobulin M syndrome, immunoglobulin A deficiency), pulmonary eosinophilias (eosinophilic granulomatosis with polyangiitis (formerly Churg-Strauss syndrome), allergic bronchopulmonary aspergillosis, chronic and acute idiopathic eosinophilic pneumonias), autoimmune blistering skin diseases (dermatitis herpetiformis, bullous pemphigoid).

Answer 6

Most eosinophilias are reactive, polyclonal processes. In all these reactive processes, the increase in AEC appears to be mediated by cytokines, principally IL-5, which promotes proliferation of eosinophils and their precursors. Reactive eosinophilias may also involve overproduction of additional cytokines, such as IL-3 and IL-4, which can lead to concomitant elevation of IgE in reactive eosinophilias.

Answer 7

This association exists because glucocorticoids inhibit eosinophil proliferation and survival, an effect that is exploited clinically when steroids are used as treatment of reactive eosinophilias. In adrenal insufficiency, the converse occurs; low glucocorticoid levels allow increased eosinophil proliferation and survival. This scenario is especially important in critically ill patients, in whom eosinophilia due to adrenal insufficiency is common. Given the inverse relationship between glucocorticoid levels and eosinophil count, the standard evaluation of eosinophilia should include attention to clinical signs of adrenal insufficiency (orthostatic hypotension, skin discoloration); routine chemistries, which may be abnormal in Addison disease; and, in some cases, morning cortisol levels.

Answer 8

Among the reactive eosinophilias in the developed world, allergic reactions are most common, comprising ~80% of cases, and parasitic infections represent the second most-common cause, comprising ~8% of cases.

Answer 9

Whereas autosomal-dominant hyperimmunoglobulin E syndrome is caused by mutations in STAT3, DOCK8 and TYK2 mutations are implicated in the comparatively rare autosomal-recessive forms of the disease.

Answer 10

Paraneoplastic eosinophilia is frequently observed in association with solid organ malignancies, with reported incidences ranging from 0.5% to 7%. The phenomenon is not specific to any particular tumor type, and a broad spectrum of primary tumors have been implicated. Instead, paraneoplastic eosinophilia appears to be most closely related to tumor stage. It has been noted that blood eosinophilia is a poor prognostic sign and, in almost all cases, is associated with advanced metastatic disease. Various mechanisms have been proposed to explain this association. The eosinophilia may disappear after surgical excision and reappear with recurrence.

Answer 11

Reactive eosinophilia is frequently observed in patients with lymphoma, often because of increased production of growth factors by the malignant cell population. In Hodgkin lymphoma, the reported incidence of blood eosinophilia is 15%. Bone marrow and tissue eosinophilia are also common, although surprisingly, there is no strong correlation with peripheral eosinophil counts. The incidence of tissue eosinophilia varies between types of Hodgkin lymphoma and is most common in the mixed cellularity form and the nodular sclerosing form of the disease. As with many reactive eosinophilias, the mechanism appears dependent on increased IL-5 levels, and possibly IgE levels, both which may be produced directly by Reed-Sternberg cells.

Answer 12

Eosinophilia may be associated with a variety of B-cell and T-cell neoplasms. B-cell lymphoblastic leukemia (BLL) with eosinophilia is one such example. It is often associated with a characteristic cytogenetic abnormality t(5;14), which juxtaposes the IL3 gene on chromosome 5 to the immunoglobulin heavy chain locus (IgH) on chromosome 14. These cases are recognized in the 2008 WHO classification as B lymphoblastic leukemia with t(5;14); IL3-IgH.” This rearrangement implies a “reactive” eosinophilia, in which increased IL-3 expression by malignant, lymphoblastic clones provides a paracrine signal, driving polyclonal expansion of the eosinophils.

Answer 13

Absolute contraindications: TTP and HIT. Immune thrombocytopenia (idiopathic thrombocytopenic purpura and post-transfusion purpura) are strong relative contraindications; Do not transfuse unless severe thrombocytopenia with life-threatening bleeding; Large numbers of units may be needed due to rapid immune destruction.

Answer 14

Generally yes, except that FP24 and 5-day cold plasma should not be used for replacement of Factor V or Factor VIII. However, selective Factor V deficiency is rare, occuring in ~1/million and the general population and is not associated with a bleeding tendency; also, Factor VIII concentrate is an available product, and cryoprecipitate can be used if factor concentrate is unavailable. So FFP, FP24, and 5-day cold plasma are basically equivalent blood products.

Answer 15

Factor VII, at 4-7 hours. Factor I is 72-120 hours, factor II is 48-120 hours, factor V is 12-36 hours, factor VIII is 8-12 hours, factor IX is 18-24 hours, factor X is 24-48 hours, factor XI is 40-84 hours, factor XII is 48-52 hours, and factor XIII is 9-12 days.

Answer 16

Factor XIII, at 9-12 days. Factor I is 72-120 hours, factor II is 48-120 hours, factor V is 12-36 hours, factor VII is 4-7 hours, factor VIII is 8-12 hours, factor IX is 18-24 hours, factor X is 24-48 hours, factor XI is 40-84 hours, factor XII is 48-52 hours.

Answer 17

Thrombocytopenia (secondary to entrapment of platelets in the tumor/Kasabach-Meritt syndrome). Microangiopathic hemolytic anemia (due to red cell fragmentation in the tumor). Disseminated intravascular coagulation.

Answer 18

POC PT/INR devices are approved for warfarin monitoring in the stabilized patient. Once the patient's dose requirements and anticoagulation effects have been stabilized for 1-2 weeks, using a central laboratory, testing can be moved to a POC device. POC PT/INR devices have not been approved for coagulation screening, testing for DIC, or use in the trauma/ED setting.

Answer 19

Hantavirus pulmonary syndrome. During the HPS prodrome, thrombocytopenia is the only dependable finding. Once pulmonary edema is established, however, there is a highly reproducible pentad of findings: thrombocytopenia, left-shifted neutrophilia, neutrophils with lack of significant toxic granulation, increased hemoglobin concentration (hemoconcentration), and >10% of lymphocytes having immunoblastic morphology. Having 4 of these 5 has a high sensitivity and specificity for HPS.

Answer 20

Of the cytokines, IL-5 is the most specific for the eosinophil lineage. It is responsible for the selective differentiation of eosinophils and release of eosinophils from bone marrow.

Answer 21

Several named syndromes are associated with eosinophilia and eosinophilic infiltration of specific organs: eosinophilic cellulitis (Well syndrome), eosinophilic pneumonia (Loeffler syndrome), eosinophilic fasciitis (Shulman syndrome), and eosinophilic vasculitis (Churg-Strauss syndrome).

Answer 22

Agranulocytosis. The effect is not dose-dependent. The incidence is 0.05-0.5% of all users. In most patients, the agranulocytosis occurs within the first 3 months of treatment. This often presents with pharyngitis, and patients are instructed to seek attention if they develop sore throat, fever, an oral ulcer, or other symptoms of infection (UTI, PNA). Minor depressions in the neutrophil count are much more common than true neutropenia.

Answer 23

Cyclic/congenital (ELA2-related) neutropenia. Kostmann syndrome. Schwachman-Diamond syndrome. Chediak-Higashi syndrome. Fanconi anemia. Dyskeratosis congenita. Benign familial neutropenias. Glycogen storage disease type Ib. WHIM syndrome (myelokathexis). Reticular dysgenesis. Wiskott-Aldrich syndrome.

Answer 24

Isolated neutropenia: Kostmann syndrome. Cyclic neutropenia. Glycogen storage disease type Ib. WHIM (myelokathexis) syndrome. Chediak-Higashi syndrome. Reticular dysgenesis. With other cytopenias: Shwachman-Diamond syndrome. Dyskeratosis congenita. Fanconi anemia. Common variable immunodeficiency. Congenital amegakaryocytic thrombocytopenia.

Answer 25

Isolated lymphopenia is uncommon but may be seen in SLE, HIV, SARS, anti-CD20 (rituxan) therapy, steroid therapy, and certain congenital immunodeficiencies (Bruton, SCID, DiGeorge, CVI).

Answer 26

With an isolated monocytopenia, consider hairy cell leukemia or steroid therapy. In patients undergoing chemotherapy, monocytopenia heralds the onset of neutropenia.

Answer 27

The four hereditary types of vWD described are type 1, type 2, type 3, and platelet-type. Type 1 is most common, at 60-80% of all vWD cases. Type 2 has four subtypes: 2A, 2B, 2M and 2N (Normandy). Type 3 is the most severe form of vWD. Platelet-type vWD, also known as pseudo-vWD, is an autosomal dominant genetic defect of the platelets; The von Willebrand factor is qualitatively normal and genetic testing of the von Willebrand gene and vWF protein reveals no mutational alteration.

Answer 28

Malaria is the single most important disease hazard from travel to developing countries. Worldwide, there are over 200 million annual cases with over 600,000 annual deaths. Hematological indicators of poor prognosis in severe malaria include a platelet count < 50 x 10E9/L, prolonged PT >3 seconds, prolonged APTT, fibrinogen < 200mg/dl, hyperparasitemia > 100,00/uL (high mortality if >500,000/uL), > 20% parasites and > 5% neutrophils containing visible malarial pigment. Early recognition and prompt management are important.

Answer 29

A serious but rare (<2% incidence) lesion that occurs in the bones and deep soft tissues of patients with hemophilia, which can be confused with simple bone cyst, aneurysmal bone cyst, osteosarcoma, or angiosarcoma. Recurrent hemorrhages with reparative changes are responsible for the clinicopathologic manifestations. In bone, they may be intraosseous or sub-periosteal and usually develop in the femur, pelvis, and tibia in adults and the small bones of the hands in children. Histologically, areas of extensive hemorrhage, thrombus formation, bone destruction, and florid new bone formation characterize this lesion and, taken out of context, can be misinterpreted as malignant. Juxtacortical and intramuscular lesions exhibit central masses of organizing blood encased by a fibrous capsule that may be composed of 3 distinct layers: an inner hemosiderin-rich collagenous layer, a central layer of dense fibrous tissue, and an outer layer rich in elastin.

Answer 30

Pseudohyperkalemia can occur in patients with extremely high blast counts in acute or accelerated phase leukemias. Those blasts can be fragile and may lyse during standard phlebotomy, releasing potassium. In contrast, specimens with very high WBC counts that are collected gently can show pseudohypokalemia when potassium is taken up by highly metabolically active leukemic cells along with glucose; such specimens can be transported on ice to slow this enzymatically mediated uptake.

Answer 31

Normally platelets release potassium during clotting, so serum has a slightly higher value of potassium than plasma from the same individual; this difference is accentuated when the platelet count is extremely elevated.

Answer 32

Oxalate anticoagulants may shrink red cells; thus blood anticoagulated with oxalate cannot be used to measure hematocrit. Combined ammonium/potassium oxalate does not have the same effect of shrinking cells.

Answer 33

Electrical impedance measurement is based on the change in electrical resistance across an aperture when a particle in conductive liquid passes through this aperture. Electrical impedance is used primarily in the hematology laboratory to enumerate leukocytes, erythrocytes, and platelets. In a typical electrical impedance instrument by Coulter, aspirated blood is divided into two separate volumes for measurements. One volume is mixed with diluent and is delivered to the cell bath, where erythrocyte and platelet counts are performed. As a cell passes through the aperture, partially occluding it, the electrical impedance increases, producing a voltage pulse, the size of which is proportional to the cell size. The number of pulses is directly related to the cell count. Particles measuring between 2 and 20 fL are counted as platelets, whereas those measuring greater than 36 fL are counted as erythrocytes. The other blood volume is mixed with diluent and a cytochemical-lytic reagent that lyses only the red blood cells. A leukocyte count is performed as the remaining cells pass through an aperture. Particles greater than 35 fL are recorded as leukocytes.

Answer 34

Practically, the best indicator for anemia is a low RBC count or number of RBCs per volume of whole blood. Although the reference range for the red cell count varies with age, sex, and population, it encompasses values from around 4–6 × 106 RBCs per cubic millimeter (cu mm) or microliter. This range may change somewhat depending on the population. RBC counts below the lower limit of the reference range suggest the presence of anemia.

Answer 35

The chromicity of the red cells (i.e., the intensity of the red color of the cells due to intracellular Hb) is measured quantitatively by the mean corpuscular hemoglobin concentration, or MCHC.

Answer 36

Moderate to severe iron deficiency anemia is associated with a increased RDW, while thalassemia and anemia of chronic disease are associated with a normal RDW.

Answer 37

Peripheral blood reticulocytosis is a measure of bone marrow response in the face of anemia. A similar measure, RPI, corrects the reticulocyte count with respect to (1) the proportion of reticulocytes present in a patient without anemia, and (2) the premature release of reticulocytes into the peripheral circulation. Bone marrow response to anemia may be appropriate (hyperproliferative) with an RPI >3, generally indicating marrow red cell hyperproliferation; however, the anemia may be due to defective RBC production or marrow failure (hypoproliferative), which is generally indicated by an RPI <2.

Answer 38

Common microcytic anemias include IDA and the thalassemias. Some hemoglobinopathies and ACD may also be microcytic.

Answer 39

ACD appears to be due to defective iron utilization/metabolism and is associated with chronic nonhematologic disorders such as chronic infections, connective tissue disorders, malignancy, and renal, thyroid, and pituitary disorders.

Answer 40

Normally, there is an equilibrium between intracellular and extracellular ferritin. The lower the stored iron becomes, the lower is the intracellular ferritin, and, consequently, the lower the extracellular ferritin becomes. The level of extracellular ferritin can be directly measured by determining the serum ferritin level, which is readily and accurately assessed on serum aliquots, using ELISA techniques. Therefore, serum ferritin levels give an excellent measure of available iron stores, noninvasively. Because iron stores in ACD are abundant, serum ferritin levels are characteristically normal to elevated. In contrast, in IDA, in which iron stores become depleted, serum ferritin levels are characteristically decreased. Thus serum ferritin level is one assay that can be used in differentiating IDA from ACD.

Answer 41

Iron binding capacity is a direct measure of the protein transferrin, which transports iron from the gut to iron storage sites in bone marrow.

Answer 42

Considerable overlap has been noted between serum levels of iron and iron-binding capacity in IDA and ACD. A somewhat more reliable discriminating measure of IDA is the ratio of serum iron to IBC, known as the transferrin saturation. This ratio is around 1 : 3 for normal individuals, and in IDA it is significantly reduced to values of around 1 : 5 or lower. Again, considerable overlap is seen even in this ratio for patients with IDA and ACD, so the values should always be interpreted with care.

Answer 43

IDA: low ferritin, increased IBC, decreased serum iron, reduced Fe/IBC ratio, generally increased RDW. ACD: generally high ferritin, normal IBC, decreased serum iron, normal Fe/IBC ratio, generally normal RDW.

Answer 44

Schistocytosis, increased reticulocytes, low haptoglobin, elevated carboxyhemoglobin, elevated LD, elevated indirect bilirubin, generally increased RDW.

Answer 45

Aplastic anemia: leukopenia, thrombocytopenia, hypocellular bone marrow, generally normal RDW. Renal failure: elevated BUN and Cr, low erythropoietin, burr cells may be present, generally normal RDW.

Answer 46

B12 and/or folate deficiency: megaloblastic, low B12 and/or folate, hyperlobulated PMNs, macroovalocytes, increased RDW. Hypothyroidism: nonmegaloblastic, elevated TSH, normal RDW.

Answer 47

After erythrocyte membrane breakdown, Hb is extruded. Extruded Hb becomes bound to the α-2 fraction protein haptoglobin. The Hb–haptoglobin complex becomes catabolized by macrophages that engulf these complexes by receptor-mediated endocytosis. Thus an excellent laboratory test for hemolytic anemia is a low haptoglobin value. Extremely sensitive and rapid ELISA assays for haptoglobin are available for this purpose.

Answer 48

When Hb is extruded, large amounts of it become oxidized to methemoglobin. The heme portion dissociates and then becomes oxidized ultimately to bilirubin. The first step in this process is the oxidative opening of the porphyrin ring of heme with attendant liberation of CO. CO may be measured easily by gas chromatographic techniques or even more conveniently by cooximetry, based on spectrophotometry, as carboxyhemoglobin. Elevated CO levels in normochromic, normocytic anemias are an excellent indicator of hemolytic anemia. Because production of bilirubin, which is unconjugated, is increased, at least a transient elevation of serum indirect bilirubin occurs. This elevation, in the presence of normal liver function, will be modest.

Answer 49

Because MHA results from traumatic destruction of newly formed RBCs in the microvasculature, where both red and white blood cell (WBC) precursors are being formed, often both RBC and WBC precursors are released into the circulation. Thus, all findings of hemolytic anemia are present, in addition to which a significant number of precursor cells such as nucleated RBCs, myelocytes, and metamyelocytes are seen in the peripheral blood—a pattern termed the leukoerythroblastic picture.

Answer 50

Schistocytes may be present on peripheral blood films as the result of mechanical (prosthetic heart valve) or thermal (severe burns) destruction. Mechanical rupture of red cells within the microvasculature may also occur by physical damage to red cells in the microvasculature of bone marrow. This may be due to space-occupying lesions, such as metastatic tumors or leukemia or lymphoma, and also myelofibrosis. Besides space-occupying lesions, other causes of this type of anemia include disease states in which fibrin is deposited on endothelial surfaces, also resulting in shearing and fragmentation of newly synthesized red blood cells, as in DIC. In this condition, an abnormal activation of the coagulation process occurs, in which fibrin–platelet clots form intravascularly and embolize to virtually any tissue. These clots block the microvasculature of tissues, including that of bone marrow, resulting in the destruction of newly synthesized red cells. In addition, other disease states may give rise to MHA that may have an immunologic component (i.e., antibodies to determinants on endothelial cells or on other structures in the microvasculature), resulting in immune complex deposits with or without fibrin deposits. These states include TTP and HUS. MHA may also occur with other immune-mediated disorders (e.g., connective tissue disorders such as disseminated lupus erythematosus), where, again, endothelial damage from the attachment of immune complexes and complement produces fibrin deposition on endothelial surfaces.

Answer 51

Another normocytic, hypoproliferative anemia is the anemia of chronic renal failure. Loss of the kidneys’ excretory function produces an increase in BUN and creatinine, as discussed later, as well as a buildup of metabolic byproducts. The resulting uremia appears to be responsible for changes in red cell shape, with burr cells (echinocytes) and ellipsoidal cells commonly present on peripheral blood films. Identification of burr cells on peripheral blood films during the course of illness may signal the development of renal dysfunction. In addition to decreased excretory function, the kidneys’ ability to produce erythropoietin is decreased, resulting in impaired erythropoiesis, such that the marrow's response to hypoxia becomes inadequate. In contrast to aplastic anemia, white cell and platelet counts usually remain within normal limits.

Answer 52

Concomitant elevations of potassium and LD in serum should be taken as indications of hemolysis that occurs artifactually after a blood sample has been taken from the patient or, less commonly, as hemolysis that results from an underlying hemolytic condition.

Answer 53

Consistently low anion gaps, typically in the range of 1–3 mEq/L, signify the presence of high levels of basic protein, often a monoclonal paraprotein as occurs in plasma cell dyscrasias. Basic protein contains ammonium ions, the counter-ions for which are chloride. Now the “invisible” ion is ammonium, and a measurable increase in chloride ion occurs. This tends to decrease the anion gap. Persistently low anion gaps are a serious sign of possible malignancy (e.g., multiple myeloma).

Answer 54

Plasma transfusion is generally indicated for coagulation factor deficiency, disseminated intravascular coagulation, dilutional coagulopathy, urgent warfarin reversal, and thrombotic thrombocytopenic purpura.

Answer 55

Anaplasma phagocytophilum (formerly Ehrlichia phagocytophilum) is a gram-negative rickettsial bacterium that is unusual in its tropism to neutrophils. It causes anaplasmosis in sheep and cattle, also known as tick-borne fever and pasture fever, and also causes the zoonotic disease human granulocytic anaplasmosis.

Answer 56

The platelet transfusion is relatively contraindicated in immune thrombocytopenic purpura. In this setting, posttransfusion platelet survival is extremely brief, and platelet transfusion is indicated only if there is severe hemorrhage.

Answer 57

Standard coagulation tests such as PT and APTT are commonly used to assess the need for plasma transfusion; however, these tests are poorly predictive of bleeding risk. In general, if the PT and APTT are less than 1.5 times the midpoint of the reference range, no benefit will be obtained from plasma transfusion. If the INR is used, in general, no benefit will be derived from plasma transfusion if it is less than 1.5, although for nervous system and retinal hemorrhage, plasma may be reasonably used unless the INR is less than 1.3.

Answer 58

The coagulation cascade concludes as thrombin converts fibrinogen into fibrin monomer. Fibrin monomers self-assemble into fibers, with growth of fibrin via end-to-end and side-to-side association of molecules. They are then covalently cross-linked by factor XIIIa at the outer D domains of adjacent fibrin monomers and the central E domain of a third fibrin monomer molecule. The structure developed within fibrin in which 2 D domains are covalently linked is referred to as D-dimer.

Answer 59

The clinical conditions associated with elevated levels of D-dimer are numerous. Some of these include thrombosis (arterial or venous), pulmonary embolism, venous thrombosis, disseminated intravascular coagulation, myocardial infarction, stroke, postoperative state, liver disease, malignancy, and pregnancy.

Answer 60

D-dimer is reported in mass units and, as these assays have evolved, 2 different types of units have been used to represent D-dimer: the fibrinogen equivalent unit (FEU) at 340 kDa and the D-dimer unit (DDU) at 195 kDa. Fibrin monomer polymerizes end to end and side to side forming a fiber, fibrin, in a process that is not enzymatically driven. The polymerization of fibrin monomer occurs with the association of the D domains of 2 fibrin monomers (referred to as D-dimer) with the E domain of a third. Soluble fragments of fibrin (fibrin degradation products) that contain variable numbers of the D-D domains (D-dimer) are produced. When assayed, the fragments are quantified in 2 different types of units, the DDU and the FEU. The mass of the FEU, related to the mass of fibrinogen, is about 1.7 times greater than the mass of the DDU. Because the D-dimer is reported in mass units, the type of units involved is very important in setting the threshold for the exclusion of venous thromboembolism and for interpretation of reported results. Adding to the complexity of reporting these values is the variability in the magnitude of units reported, for example, ng/mL, μg/mL, and μg/L. Variability in the type and magnitude of units has led to confusion in some laboratories as they attempt to use the assay, especially as they set a threshold for the exclusion of VTE.

Answer 61

An autoantibody with anti-P specificity is seen in patients with paroxysmal cold hemoglobinuria, a clinical syndrome that may occur in children following viral infection. In PCH, autoanti-P is an IgG, biphasic hemolysin capable of binding RBCs at colder temperatures, followed by intravascular hemolysis at body temperature. This characteristic can be demonstrated in vitro in the Donath-Landsteiner test.

Answer 62

An autoantibody with anti-P specificity is seen in patients with paroxysmal cold hemoglobinuria, a clinical syndrome that may occur in children following viral infection.

Answer 63

Extra antibodies. Transfusion (plasma components not type-specific to patient; IV Ig/albumin). Transplantation. Subgroup of a major blood type (especially subgroup of A (i.e. A2). Rouleaux (multiple myeloma; chronic inflammatory disorders).

Answer 64

An acquired Donull phenotype can be observed in paroxysmal nocturnal hemoglobinuria type III (PNH-III). A hematopoietic stem cell disorder, PNH III is characterized by chronic hemolysis due to an absence of all GPI-linked glycoproteins, including Dombrock, Cromer, and Cartwright antigens.

Answer 65

The Donull or Gy(a−) phenotype is a rare, autosomal recessive phenotype of the Dombrock blood group system. An acquired Donull phenotype can be observed in paroxysmal nocturnal hemoglobinuria type III (PNH-III). A hematopoietic stem cell disorder, PNH III is characterized by chronic hemolysis due to an absence of all GPI-linked glycoproteins, including Dombrock, Cromer, and Cartwright antigens.

Answer 66

Gerbich antigens are decreased in patients with hereditary elliptocytosis due to protein 4.1 (an RBC cytoskeletal protein) deficiency.

Answer 67

HDFN is the destruction of fetal or newborn RBCs by maternal alloantibodies specific for inherited paternal RBC antigen(s). The maternal IgG is transported across the placenta into the fetal circulation where it binds to the corresponding RBC antigen, targeting the antibody-coated RBCs for destruction by macrophages in the fetal spleen. The fetal marrow initially responds by increasing erythropoiesis and releases many of the newly produced RBCs into the circulation prematurely as nucleated precursors, leading to the term "erythroblastosis fetalis." With worsening anemia, erythropoiesis expands to the liver and spleen, causing organ enlargement and portal hypertension. A resulting decrease in liver production of albumin leads to reduced plasma colloid osmotic pressure, generalized edema, ascites, and effusions known as "hydrops fetalis."

Answer 68

The immature nucleated red cell also has class I antigens on its surface, but as the RBC matures the expression of class I antigens is diminished. Remnants of class I HLA antigens on red blood cells are also known as Bennet-Goodspeed (Bg) antigens. The antigens are listed with their corresponding class I HLA designation: Bga – HLA-B7, Bgb – HLA-B17, Bgc – HLA –A28.

Answer 69

HLA class II antigens are selectively expressed by dendritic cells, macrophages, B-lymphocytes, and activated T-cells that function in antigen processing and self versus non-self recognition.

Answer 70

The iadult phenotype is a rare, autosomal recessive phenotype found in <1/10,000 donors. In Asia, the iadult phenotype can be associated with congenital cataracts. i antigen is also observed on cord RBCs and reticulocytes and in megaloblastic anemia, leukemia, and chronic hemolytic states as a sign of stressed erythropoiesis. Elevated i antigen is also observed in HEMPAS (hereditary erythroblastic multinuclearity with positive acidified-serum test), a congenital dyserythropoietic anemia.

Answer 71

Anti-I and anti-i are antibodies of IgM isotype, reactive at room temperature. Autoantibodies to I are relatively common and are usually low-titered cold agglutinins. Some anti-I can have IH specificity, reacting stronger with group O and A2 RBC. Although generally benign, hemolysis secondary to high-titered anti-I is observed in cold autoimmune hemolytic anemia (CAIHA). CAIHA can occur in the setting of malignancy and occasionally infection (e.g., Mycoplasma pneumoniae). These antibodies display high thermal amplitude, often agglutinating RBCs at temperatures of 30°–34° C. In contrast, alloanti-I is relatively rare and is found as a naturally occurring antibody in iadult individuals.

Answer 72

Patients with multiple myeloma, Waldenström's macroglobulinemia, and hyperviscosity syndromes have high concentrations of abnormal serum proteins that change the net surface charge on the RBC membrane. The cells thus cluster together in clumps that resemble macroscopic hemagglutination. Plasma expanders, such as dextran and hydroxyethyl starch, as well as some intravenous X-ray contrast materials can also cause rouleaux formation.

Answer 73

Rouleaux can be differentiated from true agglutination by direct microscopy (1) by the classical “stacked-coin” formation in rouleaux, and (2) by the loss of rouleaux after washing and resuspension in saline.

Answer 74

Haptoglobin binds free hemoglobin to prevent iron loss and kidney damage during hemolysis. Any hemolytic process (immune, mechanical, environmental) can result in free hemoglobin entering the vascular system.

Answer 75

Positive acute phase reactant.

Answer 76

Haptoglobin is made in the liver as a single polypeptide chain that is cleaved post-translationally to generate alpha and beta subunits. These polypeptide chains can then be linked via disulfide bonds into four peptide chains in two pairs (alpha-beta)2 confirmation, much like hemoglobin.

Answer 77

Serum adsorption. Adsorb serum antibodies with autologous cells, selected allogeneic cells, or rabbit erythrocyte stroma (REST) at appropriate temperature for reactivity of antibody. This physically removes broadly reactive autoantibodies or alloantibodies from serum by reacting with absorbing cells to allow for detection of underlying IgG antibodies—particularly useful in cases of WAIHA.

Answer 78

Hypotonic cell lysis. The method is based on the resistance of Hg S red cells to hypotonic saline. The patient sample is repeatedly washed with 0.3% hypotonic saline to lyse normal donor red cells until gross hemolysis is no longer present. The cells are then washed and resuspended in 0.9% saline for antigen typing.

Answer 79

Individuals with warm reactive autoantibodies account for approximately 70%–80% of cases of AIHA.

Answer 80

Secondary WAIHA is often observed in autoimmune diseases (frequently systemic lupus erythematosus), in lymphoproliferative disorders, and following viral infections.

Answer 81

Autoantibodies in WAIHA are usually IgG and polyclonal in nature, showing optimal in vitro reactivity at 37° C. The DAT will be positive in approximately 80% of cases.

Answer 82

In those instances where the DAT is negative, the use of more sensitive techniques, such as radioisotope or enzyme-labeled DAT, can demonstrate low levels of IgG or, less frequently, IgM and IgA on red cells.

Answer 83

In WAIHA, causative antibodies are predominantly IgG1 and/or IgG3. Despite the ability of these subclasses to activate complement, immune destruction of the patient's autologous cells occurs largely through the spleen and liver via extravascular pathways.

Answer 84

In general, warm autoantibodies display a broad specificity, reacting with all normal RBCs. Relatively few individuals with WAIHA will show a single simple specificity.

Answer 85

Transfusion is usually avoided for as long as possible in patients with WAIHA. If transfusion is necessary, it is important to characterize the autoantibody and exclude the presence of RBC alloantibodies. Typical investigation strategies should always include adsorption of the serum (Because a strong, broadly reactive serum autoantibody can mask the presence of significant alloantibodies, adsorption studies should be performed in these patients), followed by antibody detection and identification on the adsorbed serum. Subsequent testing can also be performed on eluted antibody, although it seldom yields further useful information unless the serum is nonreactive.

Answer 86

Cold autoantibodies may be detected in the serum of many normal individuals if tested under the right conditions. However, most of these antibodies are benign cold agglutinins that show optimal reactivity at 4° C and little or no reactivity at 37° C. Cold agglutinins are often a nuisance that can interfere with ABO/Rh typing, antibody detection, and crossmatching when polyspecific AHG is used. Although usually ignored as clinically insignificant, cold agglutinins may become pathologic by virtue of expanded thermal amplitude and a significant increase in titer, frequently in association with certain disease states. DAT, serum titration, and characterization of thermal amplitude are the most important serologic tests in evaluating a possible diagnosis of CAIHA.

Answer 87

DAT, serum titration, and characterization of thermal amplitude are the most important serologic tests in evaluating a possible diagnosis of CAIHA.

Answer 88

Although usually ignored as clinically insignificant, cold agglutinins may become pathologic by virtue of expanded thermal amplitude and a significant increase in titer, frequently in association with certain disease states.

Answer 89

Cold agglutinin disease (CAD) accounts for about 20% of total cases of AIHA. As with WAIHA, CAD may be idiopathic or secondary following infection or malignancy.

Answer 90

In contrast to the anti-I cold agglutinins found in normal sera (usually less than 1 : 64 when tested at 4° C), anti-I in CAD is often of very high titer, with ranges of 1 : 10,000 to 1 : 1,000,000. The antibody also has expanded thermal amplitude, reacting with RBCs at temperatures in the range of 30°–34° C in vitro, especially in tests with albumin-suspended RBCs. The DAT is typically positive with polyspecific and anti-C3 reagents.

Answer 91

In addition to laboratory findings of intravascular hemolysis, PCH patients may have erythrophagocytosis on peripheral blood smear.

Answer 92

Autoanti-P, also known as the Donath-Landsteiner (DL) antibody, is the most common causative antibody in PCH. It is an IgG, biphasic autohemolysin capable of binding to RBCs at cold temperatures and causing intravascular hemolysis of those cells at body temperature.

Answer 93

The DL test requires that a fresh blood sample be used to ensure that an adequate supply of complement is available, because complement is relatively unstable and deteriorates during storage. The sample should be drawn and immediately stored at 37° C until clot formation. It is also important not to draw the blood into an anticoagulant such as EDTA because chelation of calcium ions will prevent complement activation and thus in vitro hemolysis.

Answer 94

A “mixed” AIHA occurs in s serum will react in all phases of testing (at room temperature and at 37° C) in the IAT. The cold-reactive antibody is typically anti-I or anti-i, and the warm-reactive antibody is typically a 37° C reactive IgG autoantibody. To adsorb autoantibody in a mixed AIHA, the sample is sequentially adsorbed at 37° C to adsorb warm-reactive autoantibody, followed by incubation in an ice bath for 30 minutes to adsorb cold-reactive antibody. Clinically, mixed AIHA usually is similar to WAIHA, although some patients may have symptoms of both WAIHA and CAD.

Answer 95

Drug-independent antibodies. Drug-dependent antibodies are subclassified into two types: Drug-dependent reactivity with drug-coated cells and Drug-dependent reactivity with uncoated cells. Nonimmunologic protein adsorption. There are also combination mechanisms.

Answer 96

Drug-independent antibodies do not require the addition of drug into the test system for detection, even though the drug is responsible for inducing hemolytic anemia. Drug-dependent antibodies, on the other hand, require the presence of the drug for serologic reactivity. Drug-dependent antibodies can be subclassified into two types, depending on whether antibody reactivity requires drug-coated red cells or simply the presence of drug in serum. Nonimmunologic protein adsorption proposes that a change in the red cell membrane causes immune globulins and other plasma proteins to be adsorbed nonspecifically to the red cell membrane. There are also combination mechanisms.

Answer 97

Myeloblast --> promyelocyte --> myelocyte --> metamyelocyte --> bands --> polymorphonuclear neutrophils.

Answer 98

Cells from the first 3 maturation stages constitute the proliferative pool, while cells from the last 3 maturation stages are postmitotic.

Answer 99

The term "large granular lymphocytes (LGLs)" usually refers to NK cells, because up to 75% of LGLs function as NK cells.

Answer 100

Left shift refers to an increased percentage of immature granulocyte forms in the peripheral blood, which may exhibit toxic granulations (prominent primary granules) and Dohle bodies (prominent secondary granules) in response to severe infections. The presence of myelocytes or even less mature granulocyte forms in peripheral blood should raise the question of an underlying hematologic malignancy or severe trauma.

Answer 101

Leukemoid reactions represent exaggerated leukocytosis (typically 50,000–100,000/mL) and may include in the peripheral blood all recognizable stages of neutrophil maturation, that is, from myeloblasts to mature granulocytes. Leukemoid reactions typically last hours to days and may be caused by either benign or malignant conditions. A leukoerythroblastic reaction caused by myelophthisis is similar (but the total WBC does not need to be high) and also includes nucleated RBCs.

Answer 102

Leukoerythroblastosis indicates severe disruption of the marrow by overwhelming infection, myelofibrosis, or bone marrow invasion by cancer, and may be associated with extramedullary hematopoiesis. A leukoerythroblastic reaction in infants can occur with severe hemolytic anemia (eg, erythroblastosis fetalis) or the rare bone disorder, osteopetrosis, in which failure of osteoclasts to resorb bone causes loss of hematopoietic marrow space and resultant extramedullary hematopoiesis.

Answer 103

Hyperleukocytosis refers to a WBC count greater than 100,000/mL, and is seen almost exclusively in leukemias and myeloproliferative disorders.

Answer 104

Leukostasis, or sludging of WBC in small vessels of the brain, lungs, and kidneys, is an oncologic emergency that may cause life-threatening cerebral infarcts, cerebral hemorrhage, or pulmonary insufficiency caused by impaired blood flow. It is most common with acute myelogenous leukemia.

Answer 105

Leukostasis is more common in acute myelogenous leukemia than in acute lymphoblastic leukemia, because myeloblasts are larger and more adhesive than lymphoblasts; it is rarely seen in chronic leukemias, even with extremely high WBC counts.

Answer 106

Because the normal spleen retains a large number of leukocytes, asplenia is associated with an increased WBC count. Splenomegaly may cause relative lymphocytosis as a result of splenic sequestration of granulocytes.

Answer 107

Corticosteroids, which demarginate granulocytes, decrease neutrophil release from the marrow, and reduce neutrophil egress from the circulation, frequently cause leukocytosis.

Answer 108

Some patients with Clostridium difficile infection or tuberculosis may manifest a leukemoid reaction with a WBC count greater than 50,000/mL. Conversely, typhoid fever, brucellosis, tularemia, rickettsial diseases, ehrlichiosis, leishmaniasis, and some cases of Staphylococcus aureus infection may be associated with leukopenia.

Answer 109

It may be related to coxsackievirus A or B6, echovirus, and adenovirus 12, and is rarely associated with splenomegaly or lymphadenopathy. Infection with EBV can cause atypical lymphocytosis (large and reactive lymphocytes with abundant basophilic cytoplasm) and lymphadenopathy. HTLV-1 may produce a transient lymphocytosis (usually <20,000/mL) with fever, rash, and lymphadenopathy. In contrast to most other bacterial infections, pertussis (whooping cough) is frequently accompanied by lymphocytosis.

Answer 110

Familial neutrophilia, an autosomal dominant disorder of prominent leukocytosis (>20,000/mL), splenomegaly, and widened diploe of the skull, is caused by a mutation in the G-CSF receptor gene (CSF3R). Neutrophils in this disorder are functionally normal and the leukocytosis has no clinical consequences.

Answer 111

Pelger-Huet anomaly (PHA) is characterized by mature neutrophils with bilobed nuclei, rather than the characteristic multilobed nuclear morphology. PHA is caused by a mutation in the lamin B receptor gene. Neutrophil function in PHA is normal, but automated cell counters may indicate a left-shifted WBC because they mistakenly classify the cells as immature granulocytes.

Answer 112

Transient myeloproliferative disorder (TMD) is seen in up to 10% of patients with Down syndrome (trisomy 21). TMD may also be seen in patients with trisomy 21 mosaicism who are phenotypically normal. TMD is characterized by peripheral blood leukocytosis in early infancy, and may include circulating myeloblasts in association with an accumulation of megakaryoblasts in the blood, liver, and marrow. TMD typically persists for several weeks and resolves spontaneously in most patients, but up to 30% of affected patients later develop acute megakaryoblastic leukemia.

Answer 113

Reticulated platelets (retPLTs) are platelets that are newly released from bone marrow megakaryocytes and still contain RNA. They have a short lifespan in the circulation and therefore reflect current megakaryopoietic activity, exactly comparable with reticulocytes and erythropoiesis. Reticulated platelets have clinical utility because they can help distinguish bone marrow failure from peripheral destruction in thrombocytopenia. Furthermore, retPLTs are an early predictor of bone marrow recovery after chemotherapy and transplantation.

Answer 114

Clinically, patients with exon 12 mutations typically present with isolated erythrocytosis and suppressed erythropoietin, in contrast to the trilineage hyperplasia characteristic of patients with V617F mutation. Bone marrow from patients with exon 12 mutation often exhibits nonspecific morphology, with isolated erythroid proliferation and absence of prominent megakaryocyte atypia and clustering. Demonstration of exon 12 mutation in these patients is particularly helpful for ruling out reactive erythrocytosis.

Answer 115

JAK2 V617F (~96%) or JAK2 exon 12 mutations (~3%).

Answer 116

False. Other hematological neoplasms (eg, myelodysplastic syndrome, chronic myelomonocytic leukemia, acute myeloid leukemia, and acute lymphoblastic leukemia) may harbor JAK2 and MPL mutations in low frequencies. Because JAK2 and MPL mutations are not completely specific for MPN, finding of these mutations in isolation does not warrant a diagnosis of MPN.

Answer 117

The JAK2 gene maps to chromosome band 9p24 and encodes a tyrosine kinase protein composed of 1132 amino acids. It contains three critical domains: JH1, JH2, and four-point-one, ezrin, radixin, moesin (FERM) homolog domains. JAK2 protein kinase activity is activated by phosphorylation of its kinase domain. Activation of JAK2 induces signal transduction from both type 1 and type 2 cytokine receptors. Constitutive activation of JAK2 by either point mutation or fusion protein causes activation of the JAK/STAT pathway. The activated JAK2 causes phosphorylation of STATs, which then dimerize and translocate to the nucleus, where they regulate gene transcription. The constitutive tyrosine phosphorylation activity promotes cytokine hypersensitivity.

Answer 118

The MPL gene maps to chromosome band 1p34 and encodes the thrombopoietin receptor, which binds to thrombopoietin, the primary cytokine that regulates megakaryocyte development and platelet production, as well as hematopoietic stem cell homeostasis. Binding to thrombopoietin to MPL leads to activation of JAK2, which phosphorylates MPL and initiates a cascade of downstream signaling events that regulate cell survival, proliferation, and differentiation. The mutation W515L results in impaired function of the autoinhibitory region and subsequent ligand-independent thrombopoietin receptor activation. This then leads to subsequent activation of downstream tyrosine kinases and activation of transcription factors STAT3 and STAT5, which in turn leads to transformation of hematopoietic cells into cytokine-independent clones, resulting in megakaryocytic hyperplasia and marrow fibrosis. The mutation Y252H, which is located in the extracellular domain of MPL, confers hypersensitivity to thrombopoietin and increases the generation of megakaryocyte colonies in vitro and leads to increased thrombopoietin signaling and cell growth and survival.

Answer 119

In unconjugated hyperbilirubinemia... If the step affected is heme conversion to unconjugated bilirubin (increased production), the pathologic process is extravascular hemolysis. If the step affected is delivery of unconjugated bilirubin to liver, the potential pathologic processes are blood shunting (cirrhosis) or right heart failure. If the step affected is uptake of unconjugated bilirubin into hepatocyte, the potential pathologic processes are Gilbert syndrome and drugs such as rifampin. If the step affected is conjugation of bilirubin in hepatocyte, the potential pathologic processes are Crigler-Najjar syndrome and hypothyroidism.

Answer 120

Physiologic jaundice. Breast milk jaundice. Polycythemia. Hemolysis (HDN, hemoglobinopathies, inherited membrane or enzyme defects). Bowel obstruction (Hirschprung disease, cystic fibrosis, ileal atresia). Inherited disorders of bilirubin metabolism (Gilbert syndrome, Crigler-Najjar syndrome).

Answer 121

A benign acquired condition (associated with celiac disease, lymphoma, HIV infection, monoclonal gammopathy, rheumatoid arthritis, and ulcerative colitis) with an incidence of ~1%, in which apparently healthy individuals have markedly elevated serum amylase levels (with low urine amylase levels), due to Ig-amylase complexes.

Answer 122

Electromotive and endosmotic. When a charge is applied (from a power source), this creates an electromotive force. The solid support has a slight negative charge and is drawn toward the positive pole (anode), but, being a solid support, it cannot move. There is instead a compensatory flow of the fluid buffer towards the negative pole (cathode). This buffer flow is called endosmosis and has the capacity to carry with it substances suspended within the medium. Since most proteins bear a net negative charge, electromotive force tends to pull them to the anode (positive pole), whereas endosmosis pulls them toward the cathode (negative pole). In most proteins, the electromotive force exceeds the endosmotic force, and they move to variable extents towards the anode. However, gamma globulins have a weak net negative charge and the endosmotic force displaces them toward the cathode.

Answer 123

MCV is the volume (in fL = 10^-9 uL = 10^-15 L) of the average circulating red blood cell. MCH is the hemoglobin content (in pg/red cell) of the average circulating red blood cell. MCHC is the hemoglobin concentration (in g/dL) within circulating red blood cells (grams of hemoglobin per 100 mL of packed red blood cells).

Answer 124

Particles with a volume 36-360 fL are counted as RBCs; leukocytes are within this size range but their relative number is usually so small that the effect is negligible. For counting WBCs, the RBCs are lysed, and particles larger than 36 fL are counted as WBCs. Particles measuring 2-20 (or 30) fL are counted as platelets.

Answer 125

Manual counting by light microscopy, optical light scatters, and flow cytometry. In the first two methods, red cells are stained with a supravital dye (such as new methylene blue or azure B) which highlight residual cytoplasmic RNA. In flow cytometry, the cells are stained with an RNA-specific fluorochrome (such as Auramine O or thiazole orange).

Answer 126

The hemoglobin solubility (dithionate) test detects insoluble forms of hemoglobin withint a lysate of blood. The sickling (metabisulfite) test detects red cells with sickling hemoglobins.

Answer 127

The hemoglobin solubility (dithionate) test detects insoluble forms of hemoglobin withint a lysate of blood. In this test, red cells are lysed in sodium dithionate buffer with saponin. After several minutes, marked turbidity indicates a positive screen. Note that this test detects free hemoglobin with altered solubility. Like the sickling (metabisulfite) test, a positive result indicates sickling hemoglobin, but gives no information on genotype and may be positive in SS, SA, SC, SD, and C harlem.

Answer 128

The sickling (metabisulfite) test detects red cells with sickling hemoglobins. In this test, whole blood is subjected to metabisulfite, which encourages cells containing HbS to sickle. A smear is then examined microscopically for sickling. Like the hemoglobin solubility (dithionate) test, a positive result does not give genotypic information and may be positive in SS, SA, SC, S-other, and C harlem.

Answer 129

The hemoglobin solubility (dithionate) test may be negative when the concentration of HbS is too small, such as in neonates. The sickling (metabisulfite) test requires at least 10% HbS to be positive, so may be negative in neonates or in those very aggressively transfused.

Answer 130

Howell-Jolly bodies - DNA fragments. Heinz bodies - Denatured, precipitated hemoglobin (visible only with supravital stain). Pappenheimer bodies - Iron-containing inclusions. Basophilic stippling - Ribosomal RNA. Hemoglobin H inclusion - Precipitated beta-hemoglobin chains (visible only with supravital stain).

Answer 131

This area is usually empty, but hemoglobin, usually absent from serum, may be present here when there is a hemolysis - a possible pseudo-M-spike.

Answer 132

No. Haptoglobin is a protein that binds free hemoglobin.

Answer 133

The haptoglobin genetic locus at 16q22 is polymorphic with two classes of alleles: type 1 and type 2. Based on these 2 alleles, the 3 haptoglobin phenotypes/protein products are: Hp 1-1, Hp 2-1, and Hp 2-2. The 2-2 phenotype is an independent risk factor for CV disease in DM.

Answer 134

The half-life of haptoglobin is 3.5 days, and the half-life of the haptoglobin-hemoglobin complex is ~10 minutes. The haptoglobin-hemoglobin complex is removed by binding to the CD163 receptors on the surface of macrophages and monocytes.

Answer 135

In ~5% of sera with an M-protein, two M-proteins are present (biclonal gammopathy). Biclonal gammopathies are typically detected when two different heavy or light chain classes of M-proteins are detected on immunofixation (eg, an IgA kappa M-protein and an IgM lambda M-protein in the same patient). Sometimes, the presence of monomers and polymers of a single M-protein may produce two spikes on the SPEP and can resemble a biclonal gammopathy (this should be considered monoclonal rather than biclonal).

Answer 136

The monoclonal gammopathies (paraproteinemias or dysproteinemias) are a group of disorders characterized by the proliferation of a single clone of plasma cells, which produces an immunologically homogeneous immunoglobulin commonly referred to as a paraprotein or monoclonal protein (M-protein or M-component, where the "M" stands for monoclonal). The M-protein can be an intact immunoglobulin (ie, containing both heavy and light chains) or can be composed of only light chains or (rarely) only heavy chains.

Answer 137

Panhypogammaglobulinemia occurs in ~10% of patients with multiple myeloma. Most of these patients have a Bence Jones protein (monoclonal free kappa or lambda light chains) in the urine, but lack intact immunoglobulins in the serum. Panhypogammaglobulinemia occurs in ~20% of patients with primary amyloidosis, often associated with a nephrotic pattern (mainly albumin with nonselective globulin loss) in the urine.

Answer 138

Waldenström macroglobulinemia, with increased concentrations of IgM, is the most common cause of hyperviscosity, but hyperviscosity can also occur in patients with high concentrations of monoclonal IgA or IgG. Serum viscosity should be determined whenever the monoclonal IgM protein spike is >4 g/dL or the IgA or IgG protein spike is >6 g/dL.

Answer 139

Serum viscosity is normally in the range of 1.5 to 1.8 centipoise (cp). Many patients have symptoms when the viscosity is >4 cp and most have symptoms when the viscosity reaches 6 to 7 cp.

Answer 140

Anopheles mosquitos. Of the approximately 430 Anopheles species, only 30-40 transmit malaria.

Answer 141

Most human cases of Babesiosis in the United States are caused by Babesia microti, which is spread in nature by Ixodes scapularis ticks (also called blacklegged ticks or deer ticks).

Answer 142

E. chaffeensis causes human monocytic erlichiosis. The vector is the Lone Star tick (Amblyomma americanum).

Answer 143

A. phagocytophila (formerly known as Ehrlichia phagocytophila) causes human granulocytic anaplasmosis. The vector is Ixodes ticks (I. scapularis in the Northeast and upper Midwest (AKA deer tick, black-legged tick, and bear tick) and I. pacificus (AKA Western black-legged tick) in the western US).

Answer 144

Increased excretion of LMW proteins can occur with marked overproduction of a particular protein, leading to increased glomerular filtration and excretion. This is almost always due to immunoglobulin light chains in multiple myeloma but may also be due to lysozyme (in acute myelomonocytic leukemia), myoglobin (in rhabdomyolysis), or free hemoglobin (in intravascular hemolysis) that is not bound to haptoglobin. In these settings, the filtered load is increased to a level that exceeds the normal proximal reabsorptive capacity.

Answer 145

Cryoglobulin is present when proteins precipitate from an individual's serum and plasma, and cryofibrinogen refers to the precipitate from plasma only. Cryoglobulins are either immunoglobulins or a mixture of immunoglobulins and complement components. Cryofibrinogen is typically composed of a mixture of fibrinogen, fibrin, fibronectin, and fibrin split products.

Answer 146

The presence of isolated monoclonal Ig (typically IgG or IgM, less commonly IgA or free immunoglobulin light chains) is the criterion for classification as a type I CG. The proportion of patients with a type I CG accounts for 5-25% of cases. The hematologic diagnoses are typically Waldenström's macroglobulinemia or multiple myeloma.

Answer 147

A mixture of polyclonal Ig in association with a monoclonal Ig, typically IgM or IgA, with rheumatoid factor activity defines type II CG. This type of CG, also called essential mixed cryoglobulinemia, accounts for 40-60% of cases. Type II CGs are often due to persistent viral infections, particularly hepatitic C and human immunodeficiency virus infections.

Answer 148

Mixed cryoglobulins consisting of polyclonal immunoglobulins characterize type III CGs. 40-50% of all CG cases are type III, and these are often secondary to connective tissue diseases.

Answer 149

The quantitative assay is based on the principle that HbF is resistant to alkali denaturation in 1.25 Molar NaOH. HbA is denatured and precipitated out; the optical density of the remaining supernatant reflects the equantity of HbF.

Answer 150

One assay is based on the principle that HbF is resistant to alkali denaturation in 1.25 Molar NaOH. HbA is denatured and precipitated out; the optical density of the remaining supernatant reflects the equantity of HbF. HPLC is also a highly accurate method for HbF quantitation.

Answer 151

Alkaline. It is "slow" and found between the origin and the C band.

Answer 152

HbH or HbBarts.

Answer 153

D, G, or Lepore.

Answer 154

Thalassemia, being a quantitative defect in production of entirely normal hemoglobins, does not produce abnormal bands. Alpha thalassemia has "thalassemic indices" (increased RBC count, low MCV) and normal Hb A2. Beta thalassemia has "thalassemic indices" (increased RBC count and low MCV) and a quantitatively increased Hb A2.

Answer 155

It does not resolve HbS from HbD, HbG, and Hb Lepore, nor does it resolve HbC, HbA2, HbO-Arab, and HbE.

Answer 156

Acid electrophoresis is still not able, in most cases, to separate HbD from HbG and HbLepore and, in some cases, HbE from HbO-Arab.

Answer 157

A1a, A1b, F, A1c (glycated), A1d (glutathioned), A1e, A0 (=HbA), A2. When S and/or C are present, they elute after A2. *F and A1c might actually be flipped.

Answer 158

HbA1: 95%-98%. HbA2: 1.5%-3.5%. HbF: < 2% (age-dependent). HbC: Absent. HbS: Absent.

Answer 159

Presence of HbS and HbF, but no HbA: Sickle cell anemia (HbSS), sickle beta0 -thalassemia (hereditary persistence of fetal hemoglobin [HPFH]), or sickle–HPFH. Overall higher proportion of HbS than HbA and HbF: Sickle beta+ -thalassemia (most likely). Presence of HbC, but with a higher proportion of HbA than HbC: HbC trait (HbAC). Presence of HbC and HbF, but no HbA: HbC disease (HbCC), HbC –beta0 -thalassemia (HbC-HPFH). A higher proportion of HbC than HbA: HbC beta+ -thalassemia. Presence of HbS and HbC: HbSC disease. Presence of HbH: HbH disease. Increased HbA2: Beta-thalassemia minor. Increased HbF: Hereditary persistence of fetal hemoglobin, sickle cell anemia, beta-thalassemia, HbC disease, HbE disease.

Answer 160

The result (in seconds) for a prothrombin time performed on a normal individual will vary according to the type of analytical system employed. This is due to the variations between different batches of manufacturer's tissue factor used in the reagent to perform the test. The INR was devised to standardize the results. Each manufacturer assigns an ISI value for any tissue factor they manufacture. The ISI value indicates how a particular batch of tissue factor compares to an international reference tissue factor. The ISI is usually between 1.0 and 2.0.

Answer 161

The RBCs of HPP patients manifest a superimposed quantitative deficiency in spectrin, which has been termed a "thalassemia-like" defect of a-spectrin. Thus, the most common scenario leading to the HPP phenotype is the combination of an elliptocytogenic a-spectrin missense mutation within one parent and a silent "thalassemia-like" defect within the other parent; when this biochemically occult allele occurs in trans to the missense mutation, the expression of the mutant spectrin is promoted and the production of normal spectrin is significantly inhibited.

Answer 162

The most severe clinical form of hereditary elliptocytosis. Severe thermal burns. Clostridial sepsis, presumably a function of the clostridial hemolysins (a-toxin, containing phospholipase C/lecithinase). Artifactual in vitro poikilocytosis due to overheating of blood samples after removal from the body, most commonly inside of motor vehicles ("pseudopyropoikilocytosis").

Answer 163

Many women of reproductive age are parvovirus B19 seronegative and are thus susceptible to a primary infection during pregnancy. The rate of vertical transmission from mother or fetus is ~33%. The risk of fetal demise is greatest in the early second trimester, when fetal immunity is sluggish. The most commonly recognized clinical manifestation of severe parvovirus B19 induced anemia is non-immune hydrops fetalis. Parvovirus is thought to cause ~10% of non-immune fetal hydrops cases.

Answer 164

HLH is a severe life-threatening syndrome caused by an abnormal hyperinflammatory response due to uncontrolled proliferation of activated lymphocytes and histiocytes which secrete increased cytokines. The etiology of HLH is related to genetic factors, viral triggers, autoimmune disease, and malignancy.

Answer 165

~30% of FHLH cases are due to mutations in the gene encoding perforin (PRF1, 10q21-22), and 20-25% of cases are due to mutations in Munc 13-14 (UNC13D, 17q25). Acquired forms of HLH are typically triggered by infections, especially viral infection such as EBV, CMV, other herpes viruses, and parvovirus B19. Other forms of infection which trigger HLH include bacterial, fungal, and protozoan infections, especially Leishmaniasis. It is important to note that genetic forms of HLH may also be triggered by infection, and isolation of a causative agent does not distinguish primary and secondary forms. Malignancies associated with HLH include primary lymphomas, an association that is more common in adults than in children. Specifically, ALCL is a frequent associated malignancy. HLH in the setting of autoimmune disease has been distinguished from other forms and is called "macrophage activation syndrome" or " reactive hemophagocytic syndrome." This is most often reported in association with systemic-onset juvenile idiopathic arthritis, but may also be seen with LE and other collagen vascular diseases.

Answer 166

Renal medullary carcinoma is very rare, with less than 100 reported cases. Age range 5 – 39 yo, average age 21 – 24 yo. Much more common in the right kidney than the left. Occurs predominantly in males (>75% of cases) and almost exclusively in African-Americans due to its relationship with sickle cell trait. Almost all reported cases have occurred in the setting of sickle cell trait or sickle cell disease. Most patients have sickle cell trait with Hemoglobin-AS (Hb-AS), however cases have been reported in patients with hemoglobin SC disease (Hb-SC) and sickle cell disease (Hb-SS). In fact, chronic medullary hypoxia due to hemoglobinopathy with subsequent chronic regenerative proliferation of the damaged epithelium has been implicated in the pathogenesis of renal medullary carcinoma.

Answer 167

Renal medullary carcinoma shows loss of INI1, while the other two retain INI1 expression.

Answer 168

ABG analyzers use a pH electrode, a PaCO2 electrode, and a PaO2 electrode to measure these variables directly. They usually also derive a % saturation of oxygen through a calculation that assums a normal hemoglobin oxygen affinity.

Answer 169

Pulse oximeters measure hemoglobin oxygen saturation directly by measuring the absorbance of transdermally transmitted light. It emits two wavelengths of light: one that deoxyhemoglobin absorbs, and one that oxyhemoglobin absorbs.

Answer 170

The co-oximeter is a spectrophotometric dvice that measures absorbance of multiple wavelengths of light. It is thus able to measure (not calculate) the proportions of oxyhemoglobin, deoxyhemoglobin, methemoglobin, and carboxyhemoglobin. Oxygen saturation is then the ratio of oxyhemoglobin to the total.

Answer 171

Co-oximetry.

Answer 172

The main function of FXIII, AKA fibrin-stabilizing factor, is the stabilization of newly formed fibrin, increasing strength and rigidity of the fibrin clot and protecting it against shear stress in the circulation, as well as protecting fibrin from prompt elimination by the fibrinolytic system. It is important in wound healing and maintenance of pregnancy. FXIII is a transglutaminase consisting of 2 potentially active, catalytic A subunits (FXIII-A) and 2 noncatalytic/carrier/inhibitory B subunits (FXIII-B). In the plasma, FXIII-B is in excess, mainly in free, noncomplexed form. Tetramers also circulate in plasma and require calcium and thrombin for activation.

Answer 173

Routine screening tests for coagulopathies (PT, aPTT, TT) do not show abnormalities in cases of FXIII deficiency. A quantitative, functional, FXIII activity assay that detects all forms of FXIII deficiency should be used as a first-line screening test.

Answer 174

Congenital FXIII deficiency can be attributed to defects in both the FXIII-A and FXIII-B genes. It is an AR trait; patients with severe disease are homozygotes or compound heterozygotes. Congenital FXIII-A deficiency may be a quantitative defect (type I deficiency) or a qualitative defect (type II deficiency). Severe FXIII-B deficiency has been rarely reported.

Answer 175

Congenital FXIII-A deficiency may be a quantitative defect (type I deficiency) or a qualitative defect (type II deficiency). Untreated, severe congenital FXIII-A deficiency causes critical bleeding events in most cases, with intracranial hemorrhage being the major cause of death. Typically, delayed-type umbilical stump bleeding represents the first classic clinical sign of congenital FXIII-A deficiency. Muscle and subcutaneous soft tissues are also preferred sites of severe bleeding complications. The FXIII-A deficiency is frequently associated with impaired wound healing and leads to abortion. Severe FXIII-B deficiency has been rarely reported.

Answer 176

Acquired FXIII deficiency with significant reduction in FXIII levels have been reported in several medical conditions such as major surgery, PE, stroke, leukemia, MDS, Crohn disease, UC, HSP, liver cirrhosis, sepsis, and DIC. In these acquired FXIII-deficient states, FXIII-A subunit levels drop to 20-70%, caused by decreased synthesis or increased consumption. Also, acquired FXIII deficiency can arise from the production of autoantibodies against FXIII subunits.

Answer 177

An autoimmune bleeding disorder that must be distinguished from regular hemorrhagic acquired FXIII deficiency (resulting from various medical conditions). AH13 tends to be more severe and requires both immunosuppressive therapy to eradicate autoantibodies and FXIII replacement therapy to stop the bleeding.

Answer 178

FFP and cryoprecipitate are good sources of FXIII, providing 1 and 3 unit/mL of FXIII respectively; however, these carry the risk of transmission of bloodbourne viruses. Pasteurized FXIII concentrates are safer and have a higher titer of FXIII (~240 U/vial), so are preferred. Also, recombinant FXIII-A is available and can be used in congenital FXIII-A subunit deficiency. The recombinant FXIII-A subunit associates in plasma with the endogenous FXIII-B subunit to form a stable FXIII heterotetramer.

Answer 179

Albumin: dec 1 g/dL. Total calcium: dec 10%. Creatinine: dec 0.3 mg/dL. Fibrinogen: inc 1-2 g/L. Albumin: dec 0.5-1 g/dL. BUN: dec 50%. Urine protein: inc to approximately double. Amylase: inc 50-100%. Hct: dec 4-7%. Hgb: dec 1.5-2 g/dL.

Answer 180

Antepartum DVT: 1/2000. Postpartum DVT: 1/700. And the incidence of PE is about 1/2500.

Answer 181

Acute fatty liver of pregnancy is a rare but serious condition - a medical emergency usually complicated by DIC. It affects about 1 in 10,000 pregnancies but has a 30% case fatality rate. It usually presents in the third trimester. Immediate delivery is the treatment of choice.

Answer 182

Normal adults score in the range of 40-120. Low LAP scores are seen in PNH, some MDSs, congenital hypophosphatasia, CML (LAP score is 0-15), and neonatal septicemia (LAP paradoxically decreased). Elevated levels (>180) are seen in leukemoid reactions, non-CML MPDs, glucocorticoid administration and 3rd trimester of pregnancy.

Answer 183

Bands and neutrophils are scored on the intensity of cytoplasmic staining from 0 to 4+ until 100 cells are counted. The number resulting from the sum of the 100 values is reported as the LAP score. Normal adults score in the range of 40-120.

Answer 184

Peripheral blood or bone marrow smears are fixed and incubated in an alkaline-dye solution of naphthol AS-MX phosphate and fast blue RR salt or fast violet B salt. As a result of phosphatase activity, naphthol AS-MX is liberated and immediately coupled with a diazonium salt, forming an insoluble, visible pigment at the sites of phosphatase activity.

Answer 185

Formerly known as glycoprotein IIb/IIIa (gpIIb/IIIa). It is an integrin complex found on platelets. It is a receptor for fibrinogen and aids in platelet activation. The complex is formed via calcium-dependent association of gpIIb and gpIIIa, a required step in normal platelet aggregation and endothelial adherence. Platelet activation by ADP leads to a conformational change in platelet gpIIb/IIIa receptors that induces binding to fibrin. Defects in glycoprotein IIb/IIIa cause Glanzmann thrombasthenia.

Answer 186

Integrin alpha-IIb (CD41) is a protein that is encoded by the ITGA2B gene. Integrin beta-3 (CD61) is a protein that is encoded by the ITGB3 gene. Alpha-IIb undergoes post-translational cleavage to yield disulfide-linked light and heavy chains that join with beta-3 to form a fibrinogen receptor expressed in platelets that plays a crucial role in coagulation. Mutations that interfere with this role result in thrombasthenia.

Answer 187

AKA protectin, complement regulatory molecule, MAC-inhibitory protein (MAC-IP), or membrane inhibitor of reactive lysis (MIRL). Regulates complement mediated cell lysis by inhibiting formation of membrane attack complex (MAC); binds to C8 or C9 components, preventing incorporation of multiple copies of C9 required for complete formation of osmolytic core. It is present on nearly all human cells. Decreased cell surface expression, along with decreased CD55 - DAF, is a feature of the affected clone in paroxysmal nocturnal hemoglobinuria.

Answer 188

Genetic defects that reduce both CD55 and CD59 on erythrocytes produce PNH.

Answer 189

Genetic defects that reduce both CD55 and CD59 on erythrocytes produce paroxysmal nocturnal hemoglobinuria.

Answer 190

Pyruvate kinase deficiency is the most common enzyme deficiency in hereditary erythrocyte disorders of the glycolytic pathway, accounting for up to 90% of cases. Hexokinase, aldolase, and phosphofructokinase deficiencies are extremely rare. G6PD, although the most common enzymatic disorder of RBCs in humans, is not an enzyme of the glycolytic pathway, but of the pentose phosphate pathway (hexose monophosphate shunt).

Answer 191

Pyruvate kinase (PK) deficiency is the most common cause of congenital non-spherocytic chronic hemolytic anemia. It is an autosomal recessive condition caused by a deficiency of erythrocytic PK. Although the gene frequency for PK deficiency is lower than that for glucose-6-phosphate dehydrogenase (G6PD) deficiency, the vast majority of patients inheriting G6PD deficiency never suffer acute or chronic hemolysis, whereas chronic hemolysis of variable severity is common in those with PK deficiency.

Answer 192

PK - glycolytic pathway. G6PD - pentose phosphate pathway (hexose monophosphate shunt).

Answer 193

The variation comes from the fact that HS can be caused by any one of several defects in cytoskeletal proteins, including band 3, protein 4.2, spectrin (alpha and beta), and ankyrin. A deficiency in any of these components can lead to the cytoskeletal instability that underlies HS.

Answer 194

Splenomegaly is common in all chronic hemolytic disorders except for sickle cell disease.

Answer 195

Increased MCHC. The MCV and MCH are usually normal but variable. While spherocytes are typically smaller than normal red cells, the MCV may be low, normal, or high, owing to reticulocytosis. Elevated LDH and bilirubin.

Answer 196

The osmotic fragility test (considered the gold standard, but misses as many as 25% of cases) is performed by incubating the RBCs in incrementally hypotonic NaCl solutions are measuring the degree of hemolysis. Spherocytic cells hemolyze more readily in hypotonic saline than normal cells; however, this test merely serves to identify the presence of spherocytes from any cause. Other tests include the autohemolysis test, acidified glycerol lysis test, and flow cytometric analysis of eosin-5'-maleimide-labeled intact RBCs.

Answer 197

Immune-mediated hemolysis and hereditary spherocytosis. Usually a DAT test and low MCV will identify the former.

Answer 198

Iron deficiency anemia, megaloblastic anemia, myelodysplasia, myelophthisis.

Answer 199

Common hereditary elliptocytosis, (hereditary pyropoikilocytosis), spherocytic elliptocytosis, and Southeast Asian ovalocytosis/stomatocytic elliptocytosis. CHE (most common in blacks) is usually asymptomatic but has a wide range of phenotypes. HPP is considered by some to be an additional type (most severe form) of HE, and by some to be a variant of CHE. SE is seen in whites.

Answer 200

MCV is increased in heavy alcohol consumption. Its sensitivity and specificity are modest, and at least 4-8 weeks of consumption are required to produce a measurable effect.

Answer 201

Lead enters the body through inhalation and ingestion. About 95% of ingested lead is distributed in erythrocytes and bone. Some also goes to the kidney where it is toxic to renal tubular cells.

Answer 202

Among the enzymes inhibited are many of the key enzymes involved in heme synthesis, particularly delta-ALA-dehydratase and ferrochelatase. This leads to an accumulation of the immediate precursor of heme, protoporphyrin (free erythrocyte protoporphyrin). FEP binds non-enzymatically to available zinc, yielding zinc protoporphyrin. Lead inhibits sodium channel ATPases, leading to increased osmotic fragility and shortened RBC survival.

Answer 203

FEP and ZPP are both increased in lead poisoning and iron deficiency.

Answer 204

Hematologic manifestations of lead toxicity include microcytic and hypochromic anemia.

Answer 205

The CDC recommendation, made in 1978 and still upheld today, is that a blood lead level greater than or equal to 10 ug/dL should be considered elevated.

Answer 206

Their advantage is they can be performed on capillary blood samples and they easily detect moderate to severe lead toxicity. One further advantage is that blood lead levels tend to misleadingly "rebound" during treatment, so that the FEP and ZPP can be used to distinguish this phenomenon from a true increase in lead toxicity.

Answer 207

Atomic absorption spectrophotometry is the preferred method for screening for lead toxicity. It is capable of detecting lead levels below the 10 ug/dL threshold. A venous sample is necessary for this determination, as capillary blood obtained from heel- or finger-sticks can give erroneous results. Furthermore, a repeat for confirmation of any abnormal screening test is advised.

Answer 208

False. CO has greater avidity for fetal hemoglobin, putting infants and fetuses at greater risk for CO poisoning.

Answer 209

Normal nonsmokers: 0.4-2%. Normal smokers: 2-6%. Mild symptoms (dyspnea on exertion): 10-20%. Severe symptoms (intoxication, headache, lethargy, loss of consciousness): 20-50%. Coma and death: >50%.

Answer 210

It is produces during the breakdown of heme. Endogenous production usually results in Hb-CO levels of 1% or less. CO is also generated in the hepatic metabolism of dichloromethane (methylene dichloride), found in paint and varnish removers.

Answer 211

A more severe, hydrocytotic type, and a less severe, xerocytotic type.

Answer 212

Hydrocytosis syndromes: significant stomatocytosis, macrocytosis, moderate to severe hemolysis, low (24-30%) MCHC. Xerocytosis syndromes: mild stomatocytosis, spiculated dessicocytes, target cells, increased MCHC.

Answer 213

Patients with hereditary stomatocytosis have a marked tendency towards thrombosis following splenectomy, so therapeutic splenectomy is generally avoided (and unnecessary). Post-splenectomy thrombotic manifestations include DVT, PE, and pulmonary HTN.

Answer 214

Patients with hereditary stomatocytosis have a marked tendency towards thrombosis following splenectomy, so therapeutic splenectomy is generally avoided (and unnecessary). Post-splenectomy thrombotic manifestations include DVT, PE, and pulmonary HTN.

Answer 215

Stomatocytosis.

Answer 216

TCR: 7. IgH: 14. Kappa: 2. Lambda: 22.

Answer 217

Beta-globin chains (beta, delta, gamma): 11 (2 copies of each per cells). Alpha-globin chains (alpha, zeta): 16 (4 copies of each per cell).

Answer 218

Reticulocytes have significantly more G6PD activity than older red cells.

Answer 219

G6PD is involved in the production of NADPH, which maintains glutathione, and consequently other proteins, in the reduced state when RBCs are subjected to an oxidant stress.

Answer 220

G6PD A- and G6PD Mediterranean. The G6PD Med mutation is much more severe due to the fact that even very young RBCs are depleted of G6PD.

Answer 221

With G6PD A- type, the steady state enzyme activity is 20-60% of normal, and reticulocytes maintain adequate G6PD levels for longer. With G6PD Med type, the steady state enzyme activity is 10% of normal, and even very young RBCs are depleted of G6PD.

Answer 222

The G6PD A- variant has steady state enzyme activity in the range of 20-60% of normal, and their reticulocytes maintain adequate G6PD levels for longer, while the G6PD Med variant has steady state enzyme activity that is 10% of normal, and their reticulocytes are already depleted of G6PD. Hence, G6PD A- will have a rise in enzyme concentration caused by reticulocytosis after a hemolytic episode, causing them to appear to have normal enzyme levels = a false negative.

Answer 223

G6PD deficiency affects 12% of African Americans.

Answer 224

Following oxidant exposure, the peripheral smear shows poikilocytosis, spherocytosis, Heinz bodies (with supravital dyes such as methyl violet, crystal violet, or brilliant cresyl blue), bite cells, and blister cells.

Answer 225

G6PD deficiency has high prevalence in Africa, southern Europe, the Middle East, Southeast Asia, and Oceania. PK deficiency has no profound geographic predilections, but has a relatively high frequency in Northern Europe and Pennsylvania Amish.

Answer 226

A myelodysplastic syndrome or acute myeloid leukemia may rarely result in acquired PK deficiency.

Answer 227

PK catalyzes the rate-limiting step in the Embden-Meyerhoff (glycolysis) pathway, which is the main generator of ATP in red cells. A by-product of the glycolytic pathway is the conversion of NADH to NAD. PK deficiency leads to ATP depletion, impaired ion pumps, red cell dehydration, and finally hemolysis.

Answer 228

Both HS and PK deficiency have a positive autohemolysis test (incubating the red cells at 37 C for 48 hrs and measuring hemolysis). However, while the autohemolysis is ameliorated in HS by incubating with excess glucose, in PK deficiency the autohemolysis does not correct with the addition of glucose and does correct with the addition of ATP.

Answer 229

For G6PD deficiency, the test is based upon the production of and then fluorescence of NADPH after G6P and NADP are added to a hemolysate of test red cells. After incubation, the sample is spotted onto filter paper, dried and examined under long wave UV light. Normal samples will fluoresce brightly, while deficient samples will fluoresce poorly or not at all. For PK deficiency, the test is based on the oxidation of NADH (fluoresces) to NAD (does not fluoresce). Test cells are incubated with ADP, PEP, and NADH (ADP + PEP = ATP + pyruvate, catalyzed by PK; then pyruvate + NADH = lactate + NAD). Normal samples will not fluoresce, while deficient samples do fluoresce.

Answer 230

In G6PD deficiency, there is no fluorescence (G6PD is not present to catalyze the production of NADPH (fluoresces) from G6P and NADP (does not fluoresce)). In PK deficiency, there is fluorescence (PK is not present to catalyze the production of pyruvate, which goes on to combine with NADH (fluoresces) to produce lactate and NAD (does not fluoresce) by the action of lactate dehydrogenase).

Answer 231

The CDAs include types I, II, III, and IV, and are a rare group of disorders that result in anemia caused by ineffective erythropoiesis and multinuclear erythroblasts. These disorders have pathognomonic cytopathologic findings consisting of nuclear abnormalities in bone marrow erythroid precursors. Type II is also called HEMPAS and is the only one out of the 4 types to have a positive acidified serum test and increased i antigen (the others have normal levels of i antigen). It is also the most common subtype.

Answer 232

HEMPAS (Hereditary Erythroblastic Multinuclearity with Positive Acidified Serum test).

Answer 233

The mean age at presentation is 5 yrs (range 1 mo to 25 yrs), but the mean age at time of correct diagnosis is 16 yrs (range 4 mos to 65 yrs).

Answer 234

Lysis in HEMPAS is observed in heterologous serum only; whereas that in PNH is seen in autologous and heterologous serum. The positive Ham test in CDA II is due to an abnormal red cell antigen to which one-third of normal individuals have an antibody.

Answer 235

The i antigen. The other subtypes of CDA (types I, III, and IV) have normal levels of i antigen.

Answer 236

PNH is a disorder characterized by a defect in the glycosylphosphatidylinositol (GPI) anchor, due to an acquired abnormality in the PIG-A (phosphatidylinositol glycan class A) gene on the X chromosome. This leads to partial or complete absence of all GPI-linked proteins, particularly CD59 (membrane inhibitor of reactive lysis) and CD55 (decay accelerating factor), resulting in an increased sensitivity of the affected cells to the action of complement.

Answer 237

Classically, though not usually, patients are described as having episodic hemolysis especially at night. Affected individuals more commonly develop a chronic, normocytic, normochromic anemia. Over time, transient thrombo- and leukopenias develop. Eventually, there may be evolution to aplastic anemia and/or AML.

Answer 238

Decreased: decay accelerating factor (DAF, CD55), membrane inhibitor of reactive lysis (MIRL, CD59), acetylcholinesterase, CD16, and CD48.

Answer 239

In the past, PNH was diagnosed indirectly based upon the sensitivity of PNH red cells to lysis by complement. The sucrose lysis test (the patient's red cells are incubated with fresh serum diluted in an isotonic sucrose solution; complement is activated under these circumstances and hemolysis of the red cells indicates a positive test) was used as a screening test and the diagnosis was confirmed by the Ham acid hemolysis test (complement is activated by reduction of the pH of fresh heterologous and homologous serum to 6.4; hemolysis of red cells in both types of sera ndicates a positive test).

Answer 240

The recognition of a deficiency of GPI-linked proteins in PNH has resulted in the development of flow cytometric methods for diagnosis, which have made the sucrose lysis and Ham tests entirely obsolete. At least 20 GPI-linked proteins are missing from the surface of PNH hematopoietic cells; the absence of any of them can be used as evidence of PNH. The abnormal red cells in PNH are either completely lacking the GPI-linked proteins (PNH III cells) or, less commonly, partially lacking (bearing about 10 percent of normal amounts of the protein, PNH II cells). Some patients have both types of abnormal PNH cells.

Answer 241

Sideroblasts are found in the bone marrow of normal, iron-sufficient subjects. They are nucleated RBC precursors (erythroblasts) with one or more iron-containing granules in the cytoplasm. In their most abnormal form (ie, ring sideroblasts), in which the granules may completely surround the nucleus, they represent the singular diagnostic feature of the sideroblastic anemias and reflect various aberrations in the processing of iron by the erythroblast.

Answer 242

Congenital sideroblastic anemia: X-linked sideroblastic anemia. Mitochondrial transporter SLC25A38 defects. Glutaredoxin 5 (GLRX5) deficiency. Erythropoietic protoporphyria. Congenital sideroblastic anemia without identified molecular defects. Sideroblastic anemia as a component of genetic syndromes (X-linked sideroblastic anemia with ataxia. Myopathy, lactic acidosis, and sideroblastic anemia. Sideroblastic anemia, B cell immunodeficiency, periodic fevers, and developmental delay. Pearson marrow-pancreas syndrome. Thiamine-responsive megaloblastic anemia syndrome). Acquired reversible/metabolic sideroblastic anemia: Alcohol. Drugs (Isoniazid. Chloramphenicol. Linezolid.). Copper deficiency/Zinc toxicity (excess zinc ingestion leads to copper deficiency). Hypothermia.

Answer 243

In sideroblastic anemia, the peripheral blood usually shows a hypochromic anemia that can be microcytic, normocytic, or macrocytic. microcytic anemia is seen more often in the inherited forms of sideroblastic anemia, while macrocytic anemia is seen more often in acquired forms. The classic finding is a wide and bimodal red cell volume distribution. RBCs with Pappenheimer bodies may be seen.

Answer 244

The amount of iron in bone marrow macrophages is strikingly increased, due to the presence of ineffective erythropoiesis (intramedullary hemolysis). Erythroid hyperplasia is present. There may be a degree of dyserythropoiesis.

Answer 245

Serum iron concentration, transferrin % saturation, and ferritin are all high. Often, due to intramedullary hemolysis associated with ineffective erythropoiesis, there is hyperbilirubinemia, high LDH, and a drop in serum haptoglobin.

Answer 246

X-linked sideroblastic anemia (XLSA). One-third of patients are women, who express the disorder because of highly skewed inactivation of their X chromosomes in hematopoietic tissue, favoring expression of the mutant allele. Numerous distinct mutations in the ALAS2 (the erythroid-specific form of 5-aminolevulinate synthase) gene have been identified. This type of sideroblastic anemia may be responsive to high doses of pyridoxine (B6).

Answer 247

One-third of patients are women, who express the disorder because of highly skewed inactivation of their X chromosomes in hematopoietic tissue, favoring expression of the mutant allele.

Answer 248

Diamond-Blackfan anemia. Aase syndrome has been described as another congenital pure red cell aplasia, but is not thought to probably be a variant of DBA rather than a distinct clinical entity.

Answer 249

Progressive normochromic, usually macrocytic anemia in infancy or early childhood. Reticulocytopenia. Normal cellularity of the bone marrow with markedly decreased or absent erythroid precursors. WBC count is generally normal; platelet counts are generally normal but can be increased or decreased. Congenital malformations (50 percent of patients). Increased risk of malignancies.

Answer 250

Parvovirus B19 infects erythroid progenitor cells, causing a maturation arrest at the pronormoblast stage. The bone marrow shows numerous giant pronormoblasts, a reduction of the more mature forms, and viral nuclear inclusions.

Answer 251

5% of patients with PRCA have a thymoma. 5-15% of patients with a thymoma have PRCA. The PRCA results from an autoimmune-mediated hypoproliferation of erythrocyte precursors in the bone marrow. This paraneoplastic disorder is more common in older women, and is usually seen with tumors that have spindle cell morphology.

Answer 252

In Blackfan-Diamond anemia, i antigen ifs often over-expressed on red cells, and the HbF is increased, whereas in TEC, both are normal.

Answer 253

Fanconi anemia. Dyskeratosis congenita. Shwachman-Diamond syndrome. Amegakaryocytic thrombocytopenia. Other inherited causes include reticular dysgenesis and Down syndrome.

Answer 254

SCN due to ELANE (neutrophil elastase gene) mutations have autosomal dominant inheritance and occurs in 60 percent of patients. SCN due to HAX1 (HCLS1-associated X1) mutations have autosomal recessive inheritance. SCN due to WASP (Wiskott-Aldrich Syndrome Protein) gene mutations have X-linked inheritance.

Answer 255

It is an autosomal recessive or X-linked chromosomal breakage syndrome that occurs in all races and ethnic groups.

Answer 256

Characteristic congenital malformations are present in up to 60-70% of children affected with Fanconi anemia, including short stature, hypopigmentation and cafe-au-lait spots, hypoplastic thumbs, microcephaly or hydrocephaly, renal abnormalities such as horseshoe kidney, and developmental delay.

Answer 257

Cytopenia develops at a median age of 7 (often mild to moderate thrombocytopenia, but mild leukopenia may also may seen as an initial presentation; anemia, when detected, is typically mild on presentation). 70% of patients have bone marrow failure by age 10.

Answer 258

Patients with FA are at high risk for developing malignancy, particularly MDS, AML (predominant type is with monocytic differentiation - M4 or M5), squamous cell carcinoma of the head and neck or vulva, as well as HCC and gastric carcinoma.

Answer 259

The diagnosis is made by the presence of increased chromosomal breakage in lymphocytes cultured in the presence of DNA cross-linking agents such as mitomycin C (MMC) or diepoxybutane (DEB).

Answer 260

Whereas normal RBCs have a lifespan of 120 days, sickled RBCs have an average lifespan in the blood of 17 days.

Answer 261

S-beta-thalasssemia, S-C, S-D, C Harlem.

Answer 262

HbA - 0%. HbA2 - 1-4%. HbF - 1-20%. HbS - >80%.

Answer 263

HbF, present at birth, has an inhibitory effect on HbS polymerization; thus, the manifestations of sickle cell disease are not apparent until HbS levels increase beyond 50%, which is usually about 6 months of age.

Answer 264

Major early fetal Hb: Hb Gower1. Minor early fetal Hb: Hb Gower2. Major late fetal Hb: HbF. Major adult Hb: HbA. Minor adult Hb: HbA2.

Answer 265

HbA: alpha2-beta2. HbA2: alpha2-delta2. HbF: alpha2-gamma2. Hb Gower1: zeta2-episilon2. Hb Gower2: alpha2-epsilon2.

Answer 266

HbA: alpha2-beta2. HbA2: alpha2-delta2. HbF: alpha2-gamma2. Hb Gower1: zeta2-episilon2. Hb Gower2: alpha2-epsilon2.

Answer 267

Acute episodes of anemia: Aplastic crisis (Parvovirus B19 accounts for nearly 70% of aplastic crises in children). Splenic sequestration (these episodes often occur during a viral illness). Hyperhemolytic crisis (this complication has been associated in many patients with concomitant G6PD deficiency). Slowly progressive worsening of anemia: Progressive renal insufficiency (with decreasing erythropoietin) or supervening iron/folate/B12 deficiency.

Answer 268

Acute pain crisis is thought to be due to a vasoocclusive event within bone. Acute chest syndrome is thought to be related to either vasoocclusive events or bacterial PNA.

Answer 269

S. pneumoniae infections, including pneumococcal sepsis, pneumonia, meningitis, and arthritis, are the most common overall. Other common infections include Salmonella, Haemophilus (HITB), and M. pneumoniae.

Answer 270

Neurologic complications are frequent in sickle cell disease, manifesting as TIA, cerebral infarcts, cerebral hemorrhage, cord infarction, sensorineural hearing loss, and meningitis. About 1 in 3 patients will have an angiographic appearance of moyamoya disease (segmental arterial stenoses with "puff of smoke" collaterals).

Answer 271

Acute sickle hepatic crisis presents with acute RUQ pain, jaundice, elevated LFTs (but not to the level seen in viral hepatitis). The pathogenesis is likely related to ischemia caused by sinusoidal obstruction, and histology may show sickle cell thrombi within sinusoidal spaces with engorgement by RBCs. Patients with SCD may acutely sequester large numbers of RBCs in the spleen, the pulmonary vasculature, and less commonly the liver. Patients with hepatic sequestration usually present with RUQ pain, rapidly increasing hepatomegaly, and a falling Hgb/Hct. The pathophysiology is believed to be obstruction of sinusoidal flow by the masses of sickled RBCs, with trapping of RBCs within the liver.

Answer 272

Gross hematuria, papillary necrosis, nephrotic syndrome, renal infarction, isosthenuria, pyelonephritis, renal medullary carcinoma.

Answer 273

Sickle cell-beta thalassemia is divided into S-beta0 thalassemia and S-beta+ thalassemia, based upon the complete absence of beta globin or the presence of reduced amounts of beta globin, respectively, which in turn determines the level of HbA. The percentage of HbA produced in individuals with beta+ thalassemia varies from 5 to 30 percent, depending upon the molecular defect of the mutation. Compound heterozygous beta0 thalassemia, results in the production of no normal beta chains and therefore no HbA.

Answer 274

Most beta thalassemia mutations among African-Americans result in beta+ thalassemia.

Answer 275

They may manifest mild isosthenuria, are at risk for splenic infarcts at high altitudes, and have a risk for renal medullary carcinoma.

Answer 276

HbA - 50-55%. HbA2 - 1-3%. HbF - <1%. HbS - 35-45%.

Answer 277

SS: HbA - 0%. HbA2 - 1-4%. HbF - 1-20%. HbS - >80%. SA: HbA - 50-55%. HbA2 - 1-3%. HbF - <1%. HbS - 35-45%.

Answer 278

The hemoglobin electrophoresis in SA shows HbA - 50-55%. HbA2 - 1-3%. HbF -

Answer 279

As with all individuals with HbS, the 2 tests are positive.

Answer 280

The gaseous form -arsine gas- is the most toxic form of arsenic, capable of producing acute renal failure, hemolysis, and death within 24-48 hrs.

Answer 281

Arsenic inhibits the oxidative production of ATP. Thus, initial toxicity is manifested in dividing tissue such as GI mucosa, with nausea, vomiting, bloody diarrhea, and abdominal pain. The marrow is affected, causing cytopenias (with erythrocyte basophilic stippling similar to that seen in lead toxicity). Chronic toxicity results in peripheral neuropathy, nephropathy, skin hyperpigmentation and hyperkeratosis (particularly palms and soles) and transverse Mees lines in the nails.

Answer 282

When alpha-thalassemia is coinherited with HbS, there is a decreased percentage of HbS (in single alpha gene deletion HbS is 30-35%; in two alpha gene deletions HbS is 25-30%). When beta-thalassemia is coinherited with HbS, there is an increased proportion of HbS (HbS is usually >50%).

Answer 283

In single alpha gene deletion (- alpha/alpha alpha), there is 30-35% HbS. In double alpha gene deletion (- -/alpha alpha or - alpha/- alpha) there is 25-30% HbS.

Answer 284

About 50% HbS. Clinical manifestations are intermediate in severity between SS and SA.

Answer 285

SS - 17 days. SC - 27 days.

Answer 286

Avascular necrosis of bone and proliferative retinopathy.

Answer 287

Mild sickling and abundant target cells.

Answer 288

A clinically insignificant delta-chain variant that occurs in 1-2% of African Americans.

Answer 289

When heterozygotes for this variant undergo gel electrophoresis, A2' is barely detectable. This may lead to underestimation of the A2 and therefore underdiagnosis of beta-thalassemia trait. A2' is easily detectable by HPLC, in which it produces a minor peak in the S area. In looking for an elevated A2 as part of excluding beta thal trait, HbA2 and HbA2' levels must be added.

Answer 290

HbS is beta6glu-->val. HbC is beta6glu-->lys. HbE is beta26glu-->lys.

Answer 291

Hemoglobin C trait (heterozygous AC) has about 40-50% of hemoglobin in the C band (HbA2 + HbC). C trait is generally asymptomatic. The peripheral blood smear has scattered target cells.

Answer 292

HbA - 0%. HbA2 - 3%. HbF - 7%. HbC - 90%.

Answer 293

There is mild hemolytic anemia and splenomegaly. PBS shows numerous target cells, and hexagonal or rod-shaped crystals may be found in the red cells especially after splenectomy.

Answer 294

CBC shows thalassemic indices and PBS shows numerous target cells.

Answer 295

Those with HbD or HbG are clinically normal. There is a band that runs with HbS on cellulose acetate and a band that runs with HbA on citrate. Often D and G can be distinguished because HbD is a beta-chain defect, while HbG is an alpha-chain defect; thus, HbG may produce two HbA2 bands (one normal, one abnormal) separated by a distance equal to that separating HbA from HbG.

Answer 296

HbD is a beta-chain defect, and HbG is an alpha-chain defect.

Answer 297

Hb Lepore is common near the Mediterranean, especially Italy. Suspect Hb Lepore whenever less than 30% (usually around 15%) HbS is present on the electrophoresis. Actual HbS is rarely present in this quantity, unless aggressively transfused.

Answer 298

Hb Lepore is the result of fusion between the delta and beta genes.

Answer 299

Hb Lepore runs with HbS on cellulose acetate. It is inefficiently produced so that it only comprises 8-15% of total Hb.

Answer 300

Hb CS results from a mutation in the alpha gene stop codon, producing an abnormally long transcript that is unstable. The alpha CS gene is thus inefficient, producing thalassemia.

Answer 301

When a hemoglobin's affinity for oxygen is high (ie, low P50), oxygen delivery to tissues is impaired, stimulating erythropoietin production and increasing the red cell mass, resulting in erythrocytosis. Conversely, in patients with hemoglobins having a low oxygen affinity (ie, high P50), oxygen delivery to the tissues is increased, often resulting in anemia and/or cyanosis.

Answer 302

Some Hb mutants have substitutions that alter the solubility of the molecule in the RBC. The intraerythrocytic precipitated material derived from the unstable abnormal Hb is detectable by a supravital stain as dark globular aggregates called Heinz bodies. These intracellular inclusions reduce the life span of the red cell and generate a hemolytic process of varied severity called congenital HB hemolytic anemia. Hb Köln is the most frequently diagnosed unstable hemoglobin in the West.

Answer 303

Hb Köln is the most frequently diagnosed unstable hemoglobin in the West.

Answer 304

The diagnosis of an unstable hemoglobin variant is established by the detection of Heinz bodies in red cells, the demonstration of hemoglobin instability in the red cell hemolysate, and the presence of pigmenturia.

Answer 305

The detection of unstable hemoglobins. The heat stability or heat denaturation test is a simple procedure in which the hemolysate is incubated for one or two hours at 50ºC [27]. Normal hemolysates are stable under these conditions; the presence of an unstable hemoglobin is signaled by the appearance of a visible precipitate. The isopropanol stability test is also useful, but can be confounded by increased levels of HbF, HbS, and methemoglobin. Mechanical agitation can also precipitate some unstable hemoglobins.

Answer 306

AKA hemiglobin or Hi. A form of hemoglobin in which iron is in the oxidized ferric (Fe+++) state instead of the usual ferrous (Fe++), often resulting from oxidation of hemoglobin. Hi is incapable of combining with oxygen.

Answer 307

Under normal circumstances, there is a small degree of hemoglobin oxidation, and up to 1.5% of total Hb is normally Hi. The small amount of Hi that normally forms is reduced in the RBC by the NADH-dependent methemoglobin reductase system. Cyanosis results when Hi reaches 10% of total Hb or around 1.5 g/dL. In such cases, the blood is grossly chocolate brown.

Answer 308

Pulse oximetry and arterial blood gas analyzers estimate oxygen saturation by emitting a red light (wavelength of 660 nm) absorbed mainly by reduced hemoglobin and an infrared light (wavelength of 940 nm) absorbed by oxyhemoglobin. Methemoglobin absorbs equally at both of these wavelengths so is essentially undetectable by these modalities.

Answer 309

Hereditary methemoglobinemia can result from either deficiency in the reductase system or abnormal hemoglobins (HbM) upon which this enzyme cannot act. HbM is a group of hemoglobins that, due to various amino acid substitutions, prefer the ferric (methemoglobin) state, which binds oxygen poorly. Acquired methemoglobinemia results from exposure to drugs or chemicals that increase the formation of Hi, common examples being nitrites, quinones, phenacetin, and sulfonamides.

Answer 310

Acquired methemoglobinemia results from exposure to drugs or chemicals that increase the formation of Hi, common examples being nitrites, quinones, phenacetin, and sulfonamides. Hi has a very high affinity for cyanide, so part of the treatment for cyanide toxicity involves administration of nitrites to generate Hi which will chelate cyanide.

Answer 311

Methylene blue, which reduces Hi to Hb.

Answer 312

SHb is formed when hemoglobin is oxidized in the presence of sulfur. If further oxidized, SHb precipitates to form Heinz bodies. SHb cannot transport oxygen. Unlike methemoglobin, SHb cannot be reduced to Hb. SHb may increase after exposure to sulfonamides and in the presence of C. perfringens bacteremia (enterogenous cyanosis).

Answer 313

Normally, SHb is less than 1% of total Hb. Cyanosis manifests at around 3-4% or 0.5 g/dL.

Answer 314

Up to 1.5% of total Hb is normally Hi; Cyanosis results when Hi reaches 10% of total Hb or around 1.5 g/dL. Normally, SHb is less than 1% of total Hb; Cyanosis manifests at around 3-4% or 0.5 g/dL.

Answer 315

There are 2 copies of the alpha genes on each chromosome 16, for a total of 4 alpha chain-producing gene loci in each normal cell. There is one copy of the beta gene on each chromosome 11, for a total of 2 productive genes in each normal cell.

Answer 316

Alpha thalassemia syndromes usually result from a large structural deletion within the translated portion of the gene, but occasionally result from a point mutation in the untranslated region. The vast majority of mutations that cause beta thalassemia consist of point mutations.

Answer 317

Beta0 alleles result in complete absence of beta-chain production, usually the result of nonsense or frameshift mutations. Beta+ alleles result in diminished beta-chain production, resulting from mutations in the promoter sequence, locus control region, or 5' untranslated region. There are also silent alleles (almost no impact on chain production - due to mutation of the promoter's CACCC box or the 5' untranslated region) and complex alleles (fusion delta-beta- and gamma-delta-beta-chains resulting from deletion of noncoding intervening segments of the HBB gene cluster).

Answer 318

Beta+ mediterranean tends to be more severe than beta+ american (seen in American blacks).

Answer 319

alpha thal 2 (alpha+ thal) refers to a genotype in which chromosome 16 has one normal and one delted alpha gene (- alpha/). This is most common in African Americans. alpha thal 1 (alpha0 thal) refers to a genotype in which chromosome 16 has two deleted alpha genes (- -/). This is prevalent in Asians.

Answer 320

Continued synthesis of normal amounts of the unaffected chain leads to its relative abundance and precipitation of these chains in the red cell, reducing the cell's lifespan. In alpha-thalassemia, beta4 and gamma4 tetramers form, while in beta-thalassemia, alpha4 tetramers form.

Answer 321

Beta-globin chain. Delta globin chain. Gamma globin chains. There is also a pseudo-HBB gene.

Answer 322

Elevated RBC count, low MCV, low Hct, normal to slightly increased RDW. An MCV/RBC count ratio 15 favors iron deficiency.

Answer 323

Alpha-thalassemia: 65-75 fL. Beta-thalassemia: 55-65 fL.

Answer 324

Microcytic hypochromic anemia with occasional target cells (more in beta-thalassemia than alpha-thalassemia), and basophilic stippling.

Answer 325

Double heterozygosity for beta-thalassemia and an abnormal beta-chain results in a an increased % of the abnormal beta-chain (eg. in S-beta-thal, there is >50% HbS with 1-15% HbF). Alpha-thalassemia results in a decreased % of abnormal beta-chains (eg. in S-alpha-thal there is 30-35% HbS with one alpha gene deletion and 25-30% HbS with two alpha gene deletions).

Answer 326

Silent carrier. Alpha-thal trait. HbH disease. Hb Bart disease (hydrops fetalis).

Answer 327

Silent carrier: - alpha/alpha alpha, normal, normal. Alpha-thal trait: - alpha/- alpha or - - /alpha alpha, thalassemic indices, normal. HbH disease: - - /- alpha or - -/alphaCS alpha, thalassemic indices and Heinz bodies, fast-migrating HbH (beta4 tetramers). Hb Bart disease (hydrops fetalis): - -/- -, hypochromia and nRBCs, fast-migrating Hb Barts (gamma4 tetramers).

Answer 328

Alpha thalassemia has manifestations at birth, while manifestations of beta thalassemia do not become evident until 6-9 months of age.

Answer 329

The alpha thal 1 genotype (one chromosome has 2 deleted alpha genes: - -/) is prevalent in Asians, while the alpha thal 2 genotype (one normal and one deleted alpha gene: - alpha/) is prevalent in African Americans.

Answer 330

Erythroleukemia (FAB M6), MPN, MDS.

Answer 331

Iron deficiency. If the results of parallel iron studies indicate iron deficiency and the % A2 is normal, electrophoresis should be repeated following iron repletion.

Answer 332

Beta thalassemia minor: beta/beta+, beta/beta0. Beta thalassemia major: beta0/beta0, beta+/beta+, beta+/beta0.

Answer 333

One of several patterns is found. In the most common situation, one sees high HbA2 (over 2.5%, usually 4-8%) and normal HbF. In the second most common situation, the electrophoresis may show normal A2 (because the patient is also iron deficient). This electrophoresis may be erroneously interpreted as consistent with alpha thalassemia.

Answer 334

In delta-beta thalassemia (deletion of both the delta and beta genes), there is normal HbA2 and increased HbF (5-20%).

Answer 335

In heterozygous Hb Lepore (fusion of delta and beta) there is normal HbA2, slightly increased HbF, and a band in the S regions comprising 6-15% (Hb Lepore).

Answer 336

The dependence of the latter on transfusions. In beta thal intermedia, hemoglobin concentrations are usually 5-10 g/dL and they usually require transfusions only when they have an intercurrent event, such as an infection, which impairs erythropoiesis. With beta thal major, starting during the first year of life, they have profound and life-long transfusion-dependent anemia.

Answer 337

Beta thalassemia intermedia is the term applied to patients with disease of intermediate severity, such as those who are compound heterozygotes of two thalassemic variants.

Answer 338

Infection. In particular, infection with Yersinia enterocolitica is a significant cause of morbidity in patients with thalassemia and other iron overload syndromes.

Answer 339

Increased HbF levels in adults are found in a number of acquired and inherited disorders. Among the inherited conditions associated with increased HbF levels in adults, some are primary and caused by mutation or genetic variation; these are termed HPFH. Others, such as those associated with sickle cell anemia and thalassemia, result from secondary responses to the dyserythropoiesis and hemolysis characteristic of these disorders, modulated by co-inherited genetic variation.

Answer 340

Developmental (trisomy 13, infants of diabetic mothers). Bone marrow regeneration (acute blood loss, transient erythroblastopenia of childhood, bone marrow transplantation, chemotherapy, following iron treatment in severe iron deficiency). Bone marrow failure syndromes (Fanconi anemia, dyskeratosis congenita, Diamond-Blackfan anemia). Leukemia (JMML, erythroleukemia). Miscellaneous (choriocarcinoma).

Answer 341

HbS-HPFH is found in about 1 in 100 patients with homozygous HbSS. These individuals have a homogeneous pancellular distribution of 25-30% HbF in adulthood and suffer from neither anemia nor vasoocclusive episodes.

Answer 342

Combined sickle cell-hereditary persistence of fetal hemoglobin, or combined sickle cell-beta thal.

Answer 343

HbS-HPFH has a pancellular distribution, while S-beta-thal has a heterocellular distribution.

Answer 344

Antiplatelet agents include aspirin, clopidogrel (Plavix), prasugrel (Effient), ticagrelor (Brilinta), and glycoprotein IIbIIIa inhibitors. Are indicated for many conditions in which platelet aggregation leads to arterial thrombosis, such as MI, angina, stroke, diabetes in those over age 30, and PAD. Aspirin blocks thromboxane A2 synthesis irreversibly. Clopidogrel, prasugrel, and ticagrelor produce inhibition of platelet ADP receptors. The IV drugs abciximab (Reopro), eptifibatide (Integrilin), and tirofiban (Aggrastat) block glycoprotein IIbIIIa receptors.

Answer 345

Anticoagulants include the oral agents warfarin (Coumadin), dabigatran (Pradaxa), rivaroxaban (Xarelto), and the IV/SQ agents unfractionated heparin, the LMW heparins enoxaparin (Lovenox) and dalteparin (Fragmin), fondaparinux (Arixtra), lepirudin (Refludan), and argatroban (no brand; generic only). Are indicated for venous thrombosis and to prevent stroke in patients with atrial fibrillation. Warfarin reduces the synthesis of the coagulation factors II, VII, IX, and X. The heparins bind to antithrombin, changing its configuration and allowing antithrombin to bind activated coagulation factors and inactivate them. Unfractionated heparin inactivates many factors. LMW heparin inactivates factors Xa and IIa (thrombin); fondaparinux inactivates only factor Xa. Lepirudin and argatroban are direct thrombin inhibitors.

Answer 346

Unlike the more common flu strains, H5N1 affects predominantly children and young adults, with a median age of 15 yrs. Lymphopenia is characteristic, without significant changes in the neutrophil, RBC, or platelet counts. The virus has tropism for non-ciliated epithelial cells of the lower respiratory tract, leading to an ARDS/DAD-like clinicopathologic picture and may explain the low rate of human-to-human transmission.

Answer 347

Alpha granules, dense or delta granules, and lysosomes. The alpha granules are the most abundant.

Answer 348

Alpha granules: thromboglobulin, P-selectin, PDGF, PF4, platelet fibrinogen, throbospondin, and VWF. Dense or delta granules: ADP, ATP, serotonin, and Ca++. Lysosomes: hydrolases.

Answer 349

Thrombin time is sensitive to heparin, while reptilase time is not.

Answer 350

Simplistically, a peripheral blood smear with giant platelets and Dohle bodies (RER) in WBCs is May-Hegglin anomaly.

Answer 351

ITP. May-Hegglin anomaly. Gray platelet syndrome. Bernard-Soulier syndrome. Velocardiofacial syndrome. Montreal platelet syndrome. Hereditary macrothrombocytopenia with hearing loss. Mediterranean macrothrombocytopenia. Sebastian syndrome. Fechtner syndrome. Epstein syndrome. Alport syndrome. Harris platelet syndrome.

Answer 352

Lacks alpha granules: Gray platelet syndrome and Quebec platelet disorder. Lacks delta/dense granules: Wiskott-Aldrich syndrome, Chediak-Higashi syndrome, and Hermansky-Pudlak syndrome.

Answer 353

Parasitic infection. Churg-Strauss syndrome. Hyper-IgE (Job) syndrome. IgE myeloma. Hodgkin lymphoma. IgE is not uniformly elevated in allergic states so is not a useful screening test in that setting.

Answer 354

T cells are exposed to mitogen, such as phytohemagglutinin or concanavalin A. Alternatively, the T cells can be exposed to cytokines such as IL-2, and the T cells proliferate in a cytokine concentration-dependent manner. Proliferation is measured by the uptake of radioactive DNA precursors (tritiated thymidine).

Answer 355

To test NK cell function. Several laboratory methods exist for determining the efficacy of antibodies or effector cells in eliciting antibody dependent cell mediated cytotoxicity (classical ADCC is mediated by NK cells, but macrophages, neutrophils, and eosinophils can also mediate ADCC). Some of these methods include chromium-51 [Cr51] release assay, europium [Eu] release assay, and sulfur-35 [S35] release assay. Although the chromium release assay is considered the gold standard test for assessing NK cell activity, flow cytometric assays for the clinical measurement of NK cell activity have also been developed.

Answer 356

An excellent screening test for neutrophils is simply the neutrophil count and peripheral smear, since most inherited defects in this arm of the immune system have readily identifiable numerical and/or morphologic findings. Also, myeloperoxidase staining can show myeloperoxidase deficiency, an AR trait which produces at most a mild immunodeficiency. But additionally, one can specifically look at chemotaxis, phagocytosis, and oxidative burst functions with various assays.

Answer 357

The nitroblue tetrazolium test.

Answer 358

It is a test used to screen for chronic granulomatous disease. Yellow NBT dye is added to neutrophils which are then stimulated. Cells capable of a normal oxidative burst will reduce the yellow NBT to a purple-blue formazan precipitate, and are said to be f+. Normal individuals will have nearly 100% f+ cells. An abnormal result, with perhaps less than 10% f+ dlls, is expected in CGD, in which deficiency of NADPH oxidase prevents the oxidative burst.

Answer 359

WASP is found mainly within hematopoietic cells and appears to be responsible for the cytoskeletal malleability that is necessary for physiologic activities.

Answer 360

Chediak-Higashi syndrome is an autosomal recessive condition that presents as neutropenia, recurrent infection, thrombocytopenia, and oculocutaneous albinism. Granulocytes, lymphocytes, and monocytes show giant cytoplasmic granules, representing abnormally fused lysosomes. The basic abnormality is defective degranulation. In late stages, an accelerated phase may develop, characterized by lymphoma-like proliferations within viscera.

Answer 361

May-Hegglin anomaly is an autosomal dominant condition manifesting as Dohle-like bodies in granulocytes and monocytes, large platelets, and thrombocytopenia. The Dohle-like bodies can be abolished by the addition of ribonuclease. 50% of patients have an abnormal bleeding history, but bleeding complications have only been documented when the platelet count falls below 80,000. Platelet aggregation studies are usually normal, and there does not appear to be much of an immune defect.

Answer 362

Alder-Reilly anomaly is mainly a morphologic finding. It is an autosomal dominant condition manifesting as large azurophilic granules resembling toxic granulation in all white blood cells. There is an association with mucopolysaccharidoses.

Answer 363

Pelger-Huet anomaly is an autosomal dominant disorder with dysfunctional segmentation of neutrophils. Bilobed neutrophils are seen rather than normally segmented forms. In homozygotes, monolobated neutrophils (Stodtmeister cells) are seen. Functionally, the cells are normal.

Answer 364

Jordan anomaly is characterized by vacuolization of leukocyte cytoplasm by fat vacuoles.

Answer 365

Coxsackie B virus infection - development of IDDM. HBV infection - polyarteritis nodosum. K. pneumoniae infection - onset of ankylosing spondylitis. Aldomet - WAIHA. Penicillamine - systemic vasculitis. Procainamide, hydralazine, and isoniazid - drug-induced SLE.

Answer 366

Type I (allergic, immediate-type): IgE; atopy, asthma, anaphylaxis. Type II (antibody-dependent, cytotoxic, antibody-mediated cellular cytotoxicity): IgM or IgG, complement, MAC; Goodpasture syndrome, autoimmune hemolytic anemia, erythroblastosis fetalis, rheumatic heart disease (also Graves disease and myasthenia gravis, but some classify these as type V). Type III (immune complex): IgG, complement, neutrophils; SLE, serum sickness, Arthus reaction, PSGN. Type IV (delayed-type, cell-mediated immune memory response, antibody-independent): T cells; tuberculin skin test, contact dermatitis, MS. Type V (an additional subtype sometimes used as a distinction from type II) (receptor mediated autoimmune disease): IgM or IgG, complement; Graves disease, myasthenia gravis.

Answer 367

Anti-Rh complex. Detection is not routinely done.

Answer 368

Anti-GPIIb, GPIIIa, GP1b, or GPV. Detection is not routinely done.

Answer 369

Amyloidosis causes an acquired factor X deficiency because factor X binds to amyloid fibrils primarily in liver and spleen, causing a shortened half-time. Factor X levels in amyloidosis range from 2-50%, but symptoms don't arise until less than 10%.

Answer 370

TA-GVHD has pancytopenia due to immune destruction of host marrow cells. Most die within 1-3 wks of symptoms due to bone marrow failure (severe hemorrhage, infection).

Answer 371

The DAT can detect as few as 150 autoantibodies bound to the RBC membrane.

Answer 372

Up to 33% of patients with autoimmune hemolytic anemia have underlying alloantibodies to red cell antigens.

Answer 373

70-80% of patients with autoimmune hemolytic anemia have warm autoantibodies, 15-20% have cold autoantibodies, and 10% have mixed AIHA.

Answer 374

For transfusion or plasma exchange in patients with TTP refractory to FFP. CRP is not deficient in ADAMTS13, the vWF-cleaving protease that is deficient in TTP.