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Heme and Lymph Exam 1 > Chapter 14: Polycythemia and Bleeding Disorders > Flashcards

Chapter 14: Polycythemia and Bleeding Disorders Flashcards

1
Q

What is the most common cause of primary polycythemia?

A

Polycythemia Vera

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2
Q

The primary pathway for the initiation of coagulation is what?

A

Tissue factor (extrinsic) pathway

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3
Q

Which test assesses the intrinsic and common clotting pathways; also monitors the treatment effect of Heparin?

A

PTT

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4
Q

Which test is used to monitor treatment effect of coumadin as well as the extrinsic and common coagulation pathways?

A

PT

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5
Q

What are the platelet counts and tests of coagulation (PT, PTT) like in bleeding disorders caused by vessel wall abnormalities?

A

Typically normal

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6
Q

Which infections are associated with vessel wall abnormalities that can cause bleeding?

A
  • Meningococcemia –> can be catastrophic if not recognized clinically
  • Septicemia + infective endocarditis
  • Rickettsioses
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7
Q

Henoch-Schonlein purpura is a cause of bleeding due to vessel wall abnormalities and is characterized by what signs/sx’s?

A
  • Purpuric rash
  • Colicky abdominal pain
  • Polyarthralgia
  • Acute glomerulonephritis
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8
Q

Serious bleeding is most often associated with what inherited disorder causing vessel wall abnormalities?

A

Hereditary hemorrhagic telangiectasia (Weber-Osler-Rendu syndrome)

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9
Q

What is the most frequent symptom/presentation of hereditary hemorrhagic telangiectasia?

A

Recurrent epistaxis

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10
Q

Which infectious agents can infect megakaryocytes leading to decreased platelet production (thrombocytopenia)?

A

HIV; one of the most common hematologic manifestations of HIV

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11
Q

How may alloantibodies against platelets be generated?

A

When platelets are transfused or cross placenta from fetus —> mother

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12
Q

What are the 2 most important non-immunologic causes of decreased platelet survival leading to thrombocytopenia?

A
  • DIC
  • Thrombotic microangiopathies (TTP and HUS)
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13
Q

Chronic immune thrombocytopenic purpura (ITP) is most commonly seen in whom?

A

Young women <40 y/o and is 3x more likely in females than males

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14
Q

What is the pathogenesis of chronic immune thrombocytopenic purpura (ITP); which antibody is most often seen?

A
  • Due to autoantibodies (IgG) against platelets
  • Anti-platelet Abs are recognized by IgG Fc receptors expressed on phagocytes —> ↑ platelet destruction
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15
Q

What is seen in the bone marrow and peripheral blood with chronic immune thrombocytopenic purpura (ITP)?

A
  • Marrow reveals moderately ↑ number of megakaryocytes
  • Peripheral blood reveals abnormally large platelets (megathrombocytes)
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16
Q

What are the clinical signs/sx’s of chronic immune thrombocytopenic purpura (ITP); often there is a history of what?

A
  • Insidious onset characterized by bleeding into the skin and mucosal surfaces
  • Cutaneous bleeding in the form of petechiae and ecchymoses
  • Often there is hx of epistaxis, easy bruising, gum bleding and hemorrhages into soft tissues w/ minor trauma
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17
Q

The thrombocytopenia of chronic immune thrombocytopenic purpura (ITP) is markedly improved following what?

A

Splenectomy

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18
Q

How is the diagnosis of chronic immune thrombocytopenic purpura (ITP) made?

A

Diagnosis of exclusion after all other causes of thrombocytopenia ruled out

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19
Q

How does acute ITP differ from chronic ITP in terms of population affected and pathogenesis?

A
  • Mainly affects children, occurring equally in males and females
  • Sx’s appear abruptly, 1-2 weeks after self-limited viral infection
  • Acute ITP, unlike chronic, is self-limited and usually spontaneously resolves within 6 months
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20
Q

Chronic ITP may sometimes first manifest with what signs/sx’s?

A

Melana, hematuria, or excessive menstrual flow

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21
Q

What are 2 serious and sometimes fatal complications of chronic ITP?

A

Subarachnoid hemorrhage and intracerebral hemorrhage

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22
Q

Which 3 drugs are most commonly indicated in causing drug-induced thrombocytopenia?

A
  • Quinine
  • Quinidine
  • Vancomycin
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23
Q

Which type of heparin-induced thrombocytopenia is most clinically significant and explain what occurs?

A
  • Type II, begins 5-14 days after initiation of therapy
  • Antibodies recognize complexes of heparin and platelet factor 4
  • Leads to activation of platelets and promotes thrombosis EVEN in the setting of thrombocytopenia
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24
Q

What are the complications which may arise with heparin-induced thrombocytopenia, type II?

A
  • Clots within large arteries may lead to vascular insufficiency and limb loss
  • Emboli from DVT’s can cause fatal pulmonary thromboembolism

*This is thrombosis occurring in the setting of thrombocytopenia, which is paradoxical to what should be happening.

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25
Q

Explain how HIV can cause both decreased production and survival of platelets?

A
  • HIV binds CD4 and CXCR4 on megakarytocytes; causing these cells to become prone to apoptosis and ↓ platelet production
  • HIV causes B-cell hyperplasia, predisposing to the development of autoantibodies, which may opsonize platelets, promoting their destruction
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26
Q

Which feature of TTP and HUS is not of primary importance like it is in DIC?

A

Activation of the coagulation cascade is NOT of primary importance; so the PT and PTT = normal

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27
Q

Thrombotic thrombocytopenic purpura (TTP) is due to a deficiency in what?

A

ADAMTS13 (aka “vWF metalloprotease)

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28
Q

What is the classic pentad of findings associated with TTP?

A
  • Fever
  • Thrombocytopenia
  • Microangiopathic hemolytic anemia
  • Transient neuro deficits
  • Renal failure
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29
Q

How do typical vs. atypical HUS differ from eachother?

A
  • Typical is highly assoc. w/ E. coli O157:H7 infection (shiga-like toxin) most commonly affecting children/older adults
  • Atypical is assoc. w/ defects in complement factor H, membrane cofactor protein (CD46) or factor I —> which normally prevent activation of alternative complement pathway
30
Q

Bernard-Soulier Syndrome illustrates the consequences of which type of platelet dysfunction; caused by what?

A
  • Defective adhesion of platelets to subendothelial matrix
  • AR inherited deficiency of platelet membrane glycoprotein complex Ib-IX; which is a receptor for vWF
31
Q

Glanzmann Thrombasthenia illustrates the consequences of what type of platelet dysfunction; what is it due to?

A
  • Defective platelet aggreggation (Mann, Agg)
  • AR deficiency of glycoprotein IIb-IIIa causing failure of platelet aggregation in response to ADP, collagen, epinephrine, or thrombin
32
Q

What are the 2 most clinically significant acquired defects of platelet function?

A
  • Ingestion of aspirin and other NSAIDs; potent irreversible inhibitor of COX’s required for synthesis of thromboxane A2 and prostaglandins
  • Uremia which involves defects in platelet adhesion, granule secretion, and aggregation
33
Q

How do hereditary vs. acquired deficiencies of clotting factors differ in the number involved?

A
  • Hereditary typically only involved ONE factor
  • Acquired usually involved MULTIPLE
34
Q

Vitamin K deficiency results in the impaired synthesis of which 5 coagulation factors?

A

Factors II, VII, IX, X and protein C

35
Q

Bleeding due to clotting factor deficiencies most often occurs into which areas of the body?

A
  • GI and urinary tracts
  • Weight-bearing joints (hemarthrosis)
36
Q

vWF stabilizes which coagulation factor?

A

Factor VIII

37
Q

Factor VIII is an essential cofactor for?

A

Factor IX

38
Q

Type 1,2, and 3 von Willebrand disease are associated with what type of defect in vWF?

A
  • Type 1 and 3 = QUANTITATIVE
  • Type 2 = QUALITATIVE
39
Q

Which is most common, type 1 or type 3 von Willebrand disease; how do they differ in pathogenesis and inheritance?

A
  • Type 1 = most common; due to autosomal dominant inheritance and is characterized by mild to moderate vWF deficiency
  • Type 3 = autosomal recessive inheritance; associated w/ very low vWF and severe disease
40
Q

What is the most common subtype of type 2 von Willebrand disease; how is it inherited and what is the pathogenesis?

A
  • Type 2A is most common and is an autosomal dominant disorder
  • vWF is expressed in normal amounts, but mutations cause defective multimer assembly
  • Associated w/ mild to moderate bleeding
41
Q

Which type of von Willebrand disease has a marked effect on the stability of factor VIII?

A

Type 3

42
Q

What is the relationship of vWF to ADAMTS13?

A

- ADAMTS13 typically degrades very high-molecular-weight multimers of vWF

- Absence of ADAMTS13 as seen in TTP leads to accumulation of these multimers in plasma promoting platelet aggregation and activation

43
Q

Prolonged PTT can be seen in which 3 inherited deficiencies of clotting factors?

A
  • vWF disease
  • Hemophilia A (Factor VIII)
  • Hemophilia B (Factor IX)
44
Q

Hemophilia A is the most common hereditary associated with what?

A

Life-threatening bleeding

45
Q

What is the inheritance pattern of hemophilia A and who is most affected?

A

X-linked recessive so affects mainly males and homozygous females

46
Q

The most severe deficiencies associated with hemophilia A are do to what type of mutation?

A

Inversion involving the X chromosome –> NO synthesis of Factor VIII

47
Q

What are characteristic signs/sx’s of symptomatic hemophilia A?

A
  • Easy bruising and massive hemorrhage after trauma or operations
  • Spontaneous hemorrhages may occur, particularly in joints (hemarthroses)
  • Recurrent bleeding into joints cause progressive deformities that can be crippling
48
Q

Which finding associated with bleeding disorders is characteristically absent in hemophilia A?

A

Petechiae

49
Q

What is required for the diagnosis of hemophilia A?

A

Factor VIII-specific assays

50
Q

Hemophilia B (Christmas Disease) is due to a deficiency in what; follows what type of inheritance?

A
  • Deficiency in Factor IX
  • X-linked recessive inheritance
51
Q

How do the lab findings for bleeding time differ between Von Willebrand disease and Hemophilia’s?

A
  • Von Willebrand = prolonged bleeding time
  • Hemophilia’s = bleeding time unaffected
52
Q

The best way to think about the pathogenesis of DIC is how?

A

Clotting + bleeding into the microcirculation

53
Q

Which mediator of endothelial injury is implicated in DIC occurring with sepsis?

A

TNF induces endothelial cells to express tissue factor on their cell surfaces, ↓ expression of thrombomodulin, and upregulates expression of adhesion molecules

54
Q

Which 2 types of cancer are most frequently associated with DIC?

A
  • Acute promyelocytic leukemia
  • Adenocarcinoma of the lung, pancreas, colon, and stomach
55
Q

The possible consequences of DIC are twofold and include what?

A
  • Widespread deposition of fibrin within microcirculation —> ischemia + microangiopathic hemolytic anemia
  • Consumption of platelets and clotting factors and activation of plasminogen, leading to hemorrhagic diathesis
56
Q

Which unusual form of DIC occurs in association with giant hemangiomas?

A

Kasabach-Merritt syndrome, where thrombi form within neoplasm because of stasis and recurrent trauma to fragile vessels

57
Q

What is the acute vs. chronic presentation of DIC most often associated with?

A
  • Acute, as seen w/ obstetric complications or major trauma is dominated by bleeding diathesis
  • Chronic, such as occurs in cancer pt’s, tends to present w/ thrombotic complications
58
Q

Severe cases of DIC can cause what in the kidney?

A

Bilateral renal cortical necrosis

59
Q

What is the most common complicaton of transfusions; how does it present?

A
  • Febrile NON-hemolytic reaction
  • Fever + chills, sometimes mild dyspnea, within 6 hours of a transfusion of red cells or platelets
60
Q

Allergic reactions following transfusions are most common in which patients; occurs how?

A
  • Those w/ IgA deficiency

- IgG Abs recognize IgA in the infused blood product

61
Q

What are the cause of acute hemolytic reactions following blood transfusions?

A

Preformed IgM Abs against donor red cells that fix complement

62
Q

Which test will be positive in a patient with acute hemolytic reaction following blood transfusion?

A

Direct Coombs test (+)

63
Q

Signs/sx’s of acute hemolytic reaction following transfusion; what is the underying cause of them?

A
  • Rapid appearance of fever + shaking chills + flank pain
  • Due to complement activation
  • Produces hemoglobinuria without any other sx’s of hemolytic anemia
64
Q

Acute hemolytic reactions following a blood transfusion most often are caused by what?

A

Human error, either pt identification or tube labeling = pt receives ABO incompatible blood

65
Q

What is the cause of delayed hemolytic reactions following a transfusion?

A

Due to IgG Ab’s against red cell Ag the patient was previously sensitized to

66
Q

Which labs are indicative of delayed hemolytic reactions following transfusion?

A
  • Direct Coombs test (+)
  • Labs typical of hemolysis (i.e, low haptoglobin and ↑ LDH)
67
Q

What occurs in Transfusion-Related Acute Lung Injury (TRALI)?

A

Transfused blood product triggers activation of neutrophils in the lung microvasculature

68
Q

Most common Ab’s associated with TRALI are those that bind what; who is this most often seen in?

A

Abs that bind MHC class I Ags; often found in multiparous women

69
Q

What is the presentation of TRALI like; what is seen on imaging?

A
  • Dramatic, rapid onset of respiratory failure following transfusion
  • Other findings include: fever, hypotension and hypoxemia
  • Bilateral pulmonary infiltrates seen on CXR
70
Q

TRALI is most likely to occur when using what transfusion products?

A

Those w/ high levels of donor Abs such as fresh frozen plasma and platelets

71
Q

Significant bacterial contamination is more likely with what type of blood products?

A

Platelets (must be stored at room temp.)

Heme and Lymph Exam 1 (14 decks)

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