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Hematology > 111 Platelet Disorders > Flashcards

111 Platelet Disorders Flashcards

1
Q

What is the treatment of ITP with severe thrombocytopenia without significant bleeding?

A

Prednisone

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2
Q

Dynamic process in which platelets and blood vessel wall play key roles

A

Hemostasis

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3
Q

Major regulator of platelet production and where is it synthesized?

A

Thrombopoietin TPO which is synthesized in the liver

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4
Q

Increased synthesis of platelet is associated with inflammation and what interluekin?

A

Interluekin 6

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5
Q

What is the average lifespan of platelets?

A

7 to 10 days

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6
Q

Large multimeric protein present in both plasma and extracellular matrix of the sub endothelial vessel wall which platelet adhere to

A

VWF

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7
Q

Signals platelet aggregation

A

Glycoprotein IIb/IIIa

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8
Q

Stabilized platelet plug and develops simultaneously as product of coagulation cascade

A

Fibrin

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9
Q

Processes that leads to thrombocytopenia

A
  1. Decreased bone marrow production
  2. Sequestration in the spleen
  3. Increased platelet destruction
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10
Q

Key step in evaluating a patient with thrombocytopenia

A

Review the peripheral blood smear

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11
Q

What is pseudothrombocytopenia?

A

In vitro artifact resulting from platelet agglutination via antibodies form the calcium content in the blood collection
(EDTA anticoagulated blood)
Remedy: collect blood in sodium citrate (blue top tube) or heparin (green top tube)

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12
Q

Platelet count to maintain vascular integrity in the microcirculation

A

Platelet count of 5-10K

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13
Q

Pinpoint non blanching hemorrhages and are usually a sign of decreased platelet number and not platelet dysfunction

A

Petechaie

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14
Q

Most common noniateogenic cause of thrombocytopenia

A

Viral and bacterial infection

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15
Q

Platelet count less than 150K. Hgb and WBC count abnormal. Whats the next step?

A

Bone marrow examination

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16
Q

Platelet count less than 150K. Hgb and WBC count normal. Whats the next step?

A

Peripheral blood smear

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17
Q

Platelet count less than 150K. Hgb and WBC count normal. PBS show clumped platelets. What’s the next step?

A

Redraw in sodium citrate or heparin

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18
Q

Platelet count less than 150K. Hgb and WBC count. PBS fragmented RBC. What’s the diagnosis?

A

Micrioangiopathic hemolytic anemia (DIC, TTP)

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19
Q

Platelet count less than 150K. Hgb and WBC count normal. PBS normal RBC. Normal Platelets. What are the considerations?

A

Drug induced thrombocytopenia
Infection induced thrombocytopenia
Idiopathic immune thrombocytopenia
Congenital thrombocytopenia

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20
Q

What differentiates HIT from other drug induced thrombocytopenia

A
  1. In HIT, thrombocytopenia is not usually severe with nadir counts rarely less than 20K
  2. Hit is not associated with bleeding but with markedly increased risk for thrombosis
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21
Q

Pathophysiology of HIT

A

Antibody formation to heparin. Protein platelet factor 4 (PF4) attached to heparin to form a complex. The anti hepatrin/PF4 antibody activates platelets through the FcYRIIa receptor and also activates monocyte and endothelial cells

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22
Q

True or false. HIT is more common in UFH than in LWH.

A

True

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23
Q

When do patient manifest HIT?

A

5-10 days after exposure to heparin

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24
Q

4T in the diagnostic algorithm of HIT

A

Thrombocytopenia
Timing of drop of platelet count
Thrombosis such as localized skin reaction
Other cause if thrombocytopenia not evident

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25
Q

How is HIT diagnosed? What laboratory tests are used for HIT?

A 
HIT remains a clinical diagnosis
Test for HIT
ELISA with PF4/polyanion complex
IgG ELISA
Platelet activation assat (serotonin release)
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26
Q

Why is ELISA PF4/polyanion has low specificity in what population of patient?

A

Low specificity among patibes who undergone cardiopulmonary bypass surgery where 50% develop antibodies postoperatively

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27
Q

Common complication of HIT

A

Thrombosis both arterial and venous

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28
Q

Drugs effective in HIT thrombosis. How long should it ge given?

A

Direct thrombin inhibitors like argatroban, bivalirudin
Anti thrombin binding polysaccharides like fondaparinux
Then transitions to warfarin

Given a few days after platelet recovery for for 1 month

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29
Q

Can you give warfarin immediately to HIT thrombosis?

A

No as aspirin may lead to venous gangrene due to Clotting activation and severely reduced level of protein C and S

30
Q

Acquired disorder in which there is immune mediated destruction of platelets and possibly inhibition of platelet release from megakaryocyte

A

Idiopathic thrombocytopenia purpura

31
Q

Autoimmune disease commonly associated with secondary ITP

A

SLE

32
Q

Infections commonly associated with ITP

A

HIV and hepatitis C

33
Q

Pathogen assosciated with ITP

A

H. Pylori

34
Q

Autoimmune hemolytic anemia with ITP

A

Evan’s syndrome

35
Q

Mechanism of action is production of limited hemolysis with antibody coated cells saturating the Fc receptors, inhibiting FC receptor function

A

Rh0D immune globulin

36
Q

Rare complication of Rh0D immune Globulin

A

Severe intrvascular hemolysis

37
Q

Treatment options for ITP

A
  1. Glucocorticoids: prednisone
  2. Rh0D immune Globulin
  3. IVIg
  4. TPO receptor agonist: romiplostim (SQ) and eltrombopag (oral)
38
Q

Common feature among inherited thrombocytopenia

A

Large platelets

39
Q

Group of disorders characterized by thrombocytopenia, micrioangiopathic hemolytic anemia evident by fragmented RBCs. Examples?

A

Thrombotic thrombocytopenic micrioangiopathies

Examples: TTP, hemolytic uremic syndrome

40
Q

Differentiate between DIC and thrombocytopenic micrioangiopathies

A

DIC: consumption of Clotting factors

TTP and HUS: normal PT and aPTT

41
Q

Other name of inherited TTP

A

Upshaw-Schulman syndrome

42
Q

Pathophysiology of TTP

A

Deficiency of metalloprotease ADAMTS13 which cleaves VWF

43
Q

Findings to support TTP?

A 
Increased LDH
Increased Indirect bilirubin
Decreased haptolgobin
Increased Reticulocyte count
Negative antiglobulin tests
44
Q

Main stay treatment of TTP

A

Plasma exchange

45
Q

Syndrome characterized by acute renal failure, micrioangiopathic hemolytic anemia and thrombocytopenia. Often preceeded by an episode of diarrhea

A

Hemolytic Uremic Syndrome

46
Q

Most frequut etiologic serotype of HUs

A

E coli O157:H7

47
Q

Primary treatment of HUS

A

Supportive

48
Q

Humanized monoclonal antibody against C5 that blocks terminal complement and has efficacy in resolution of HUS

A

Eculizumab

49
Q

Causes of thrombocytosis

A 
Iron deficiency
Inflammation
Cancer
Infection
Essential thrombocythemia
Rarely: 5q- Myelodysplastic process
50
Q

True or false. Thrombocytosis in response to acute or chronic inflammation is associated with increased thrombotic risk

A

False.

51
Q

Inherited disorder absence of platelet Gp Ib-IX-V receptor

A

Bernard Soulier

52
Q

Inherited disorder. Absence of platelet Gp IIb/IIIa receptor

A

Glanzmann thrombasthenia

53
Q

Classic autosomal dominant qualitative platelet disorder resulting from abnormalities of platelet granule formation

A

Platelet storage pool disorder

54
Q

Most common inherited disorders of platelet function prevent normal secretion of granule content

A

Secretion disorders

55
Q

Treament for inherited disorders of platelet dysfunction

A

Platelet transfusion
Tranexamic acid
Desmopressin/DDAVP

56
Q

Treament for inherited disorders of platelet dysfunction

A

Platelet transfusion
Tranexamic acid
Desmopressin/DDAVP

57
Q

Common cause of acquired platelet dysfunction

A

Medication: antiplatelet or penicillins

58
Q

What is the platelet dysfunction in Uremia?

A

Defective adhesion and activation
improved by dialysis or
increasing hematocrit by 27-32%
DDAVP

59
Q

Most common inherited bleeding disorder

A

Von willebrand disease

60
Q

What is the role of VWF

A
  1. Major adhesion molecule that tethers the platelet to the exposed subendothelium
  2. Binding protein for FVIII resulting in significant prolongation of the FVIII half life circulation
61
Q

Most common type of VWD

A

Type 1: parallel decrease in VWF protein, VWF function and FVII level

62
Q

Common manifestation of VWD in female

A

Menorrhagia

63
Q

Which blood type has decreased levels of VWF

A

Blood type O

64
Q

VWD variant where gene affecting binding of FVIII; also known as autosomal hemophilia

A

Type 2N

65
Q

VWD variant describes patient with virtually no VWF and FVIII levels less than 10%

A

Type 3

66
Q

VWD variant describes increased susceptibility to cleavage by ADAMTS13

A

Type 2A

67
Q

VWD variant describes increased spontaneous binding of VWF to platelets in circulation

A

Type 2B

68
Q

Aortic stenosis with GI bleeding; attributed to prescience of angiodysplasia of the GI tract

A

Heyde Syndrome

69
Q

Treatment of VWD

A

DDAVP: releases VWF and FVIII from the endothelial stores

70
Q

True or false. DDAVP has 2h peak activity when given intranasally compared to 30 mins if IV.

A

True

71
Q

Major side effect of DDAVP

A

Hyponatremia

72
Q

What the use of vitamin C

A

Synthesize hydroxy proline which is an essential constituent of collagen

Hematology (11 decks)

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