Platelets: Qualitative and Quantitative Disorders Flashcards

1
Q

3 functions of von Willebrand Factor (vWF)

A
  • Carrier protein for Factor VIII (VIII:C)
  • Participates in platelet’s adhesion to subendothelial collagen
  • Facilitates a normal aggregation response to ristocetin
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2
Q

von Willebrand disease

- Pathogenesis

A

Clinical disorder due to deficiency of vWF

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3
Q

von Willebrand disease

- Bleeding time results

A

Increased

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4
Q

von Willebrand disease

- Closure time results (PFA)

A

Increased

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5
Q

von Willebrand disease

- Platelet adhesion result

A

Abnormal

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6
Q

von Willebrand disease

- Platelet aggregation w/ ristocetin

A

Abnormal ristocetin induced aggregation

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7
Q

von Willebrand disease

- Platelet count

A

Can be normal or abnormal → not a hallmark

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8
Q

von Willebrand disease

- APTT result

A

Prolonged due to ↓ VIII:C

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9
Q

Bernard-Soulier syndrome

- Pathogenesis

A

Missing GPIb/IX receptor complex

- Platelets cannot adhere to subendothelium via vWF

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10
Q

Bernard-Soulier syndrome

- Bleeding time result

A

Prolonged

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11
Q

Bernard-Soulier syndrome

- Platelet aggregation w/ ADP and ristocetin

A
  • ADP: normal

- Ristocetin: abnormal

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12
Q

Bernard-Soulier syndrome

- Platelet adhesion result

A

Abnormal

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13
Q

Bernard-Soulier syndrome

- Platelet count

A

Decreased

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14
Q

Bernard-Soulier syndrome

- Platelet morphology

A

Giant platelets

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15
Q

Glanzmann’s thrombasthenia

- Pathogenesis

A

Missing GPIIb/IIIa receptor complex

- Platelets cannot bind to fibrinogen and bridge/attach to one another → cannot aggregate

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16
Q

Glanzmann’s thrombasthenia

- Bleeding time result

A

Prolonged

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17
Q

Glanzmann’s thrombasthenia

- Platelet adhesion result

A

Normal

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18
Q

Glanzmann’s thrombasthenia

- Platelet aggregation w/ ADP and ristocetin

A
  • ADP: abnormal

- Ristocetin: normal

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19
Q

Glanzmann’s thrombasthenia

- Platelet count

A

Normal

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20
Q

Glanzmann’s thrombasthenia

- Platelet morphology

A

Normal

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21
Q

5 acquired qualitative platelet disorders

A
  • Drug therapy (most common cause)
  • Renal disease (uremia)
  • Dysproteinemias
  • Liver disease
  • Platelet Abs
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22
Q

4 general causes for thrombocytopenia

A
  • ↓ platelet production
  • Ineffective thrombopoiesis
  • Abnormal distribution of platelets
  • ↑ destruction of platelets
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23
Q

Destruction occurs by processes other than the immune system (consumption, mechanical destruction)

A

Nonimmune-mediated platelet destruction

24
Q

Platelets become sensitized w/ Abs and RES, especially the spleen, destroys them

A

Immune-mediated platelet destruction

25
Q

3 causes of nonimmune-mediated platelet destruction for thrombocytopenia

A
  • Thrombotic thrombocytopenic purpura (TTP)
  • Hemolytic uremic syndrome (HUS)
  • Disseminated intravascular coagulation (DIC)
26
Q

3 causes of immune-mediated platelet destruction for thrombocytopenia

A
  • Idiopathic thrombocytopenic purpura (ITP)
  • Drug-induced → heparin-induced thrombocytopenia (HIT)
  • Neonatal alloimmune thrombocytopenia
27
Q
Thrombocytopenic purpura (TTP)
- Predisposing factors
A
  • Infectious diseases
  • Autoimmune diseases
  • Drugs
  • Pregnancy
  • Hereditary
28
Q
Thrombocytopenic purpura (TTP)
- Clinical presentation
A

Characterized by
- MAHA (jaundice, pallor, acute renal failure)
- Thrombocytopenia
- Neurologic dysfunction (headaches, seizures, vertigo, delirium)
Mostly in adults

29
Q
Thrombocytopenic purpura (TTP)
- Platelet count
A

Decreased

30
Q
Thrombocytopenic purpura (TTP)
- Lab findings
A
  • ↓ RBC, hemoglobin, hematocrit
  • ↑ reticulocytes
  • SCHISTOCYTES
  • Coag tests (PT, APTT) usually normal but it helps to distinguish from DIC
31
Q
Thrombocytopenic purpura (TTP)
- Type of anemia/mechanism
A

Hemolytic anemia???
Underlying disorder that damages vascular endothelium*
- Caused by ultra high molecular weight vWF multimers present when endothelium-secreted vWF isn’t properly proteolysed by its cleaving protease
- Promotes deposition of platelet thrombi (platelet consumption, fragmented RBCs leading to intravascular hemolysis)

32
Q

Hemolytic uremic syndrome (HUS)

- Predisposing factors

A

Acquired disorder that resembles TTP
Characterized by
- MAHA
- Thrombocytopenia

33
Q

Hemolytic uremic syndrome (HUS)

- Clinical presentation in contrast to TTP

A
  • Usually no neurological manifestations
  • Intravascular clotting confined to the kidney leading to acute renal failure
  • Associated w/ bacterial toxins
34
Q

Hemolytic uremic syndrome (HUS)

- Platelet count

A

Decreased

35
Q

Hemolytic uremic syndrome (HUS)

- Lab findings

A
  • Similar to TTP

- Additionally, abnormal urinalysis results: proteinuria, hematuria, RBC casts often

36
Q

Hemolytic uremic syndrome (HUS)

- Clinical findings in children

A
  • Classic HUS occurs in infants <2 yrs age

- Children present after a febrile illness with: vomiting, bloody diarrhea, MAHA leads to renal failure, hypertension

37
Q

Hemolytic uremic syndrome (HUS)

- Clinical findings in adults

A

Link w/ malignancy and/or chemotherapy

38
Q
Acute idiopathic (immune) thrombocytopenic purpura (ITP)
- Age of onset
A

Childhood

39
Q
Acute idiopathic (immune) thrombocytopenic purpura (ITP)
- Previous infections?
A

Common

40
Q
Acute idiopathic (immune) thrombocytopenic purpura (ITP)
- Platelet count
A

Decreased (< 20,000/uL), so BM exam requested

41
Q
Acute idiopathic (immune) thrombocytopenic purpura (ITP)
- Bleeding characteristics
A

Abrupt onset of bruising, petechiae, and sometimes mucosal bleeding in a previously healthy patient

42
Q
Acute idiopathic (immune) thrombocytopenic purpura (ITP)
- Occurrence of spontaneous remission
A

Occurs in majority of patients

43
Q
Acute idiopathic (immune) thrombocytopenic purpura (ITP)
- Treatment
A
  • Some patients do not require treatment due to spontaneous remissions
  • Severe causes require platelet transfusions and/or splenectomy (as spleen is primary site of platelet destruction)
44
Q
Chronic idiopathic (immune) thrombocytopenic purpura (ITP)
- Age of onset
A

20-50 years old, females over males

45
Q
Chronic idiopathic (immune) thrombocytopenic purpura (ITP)
- Previous infections?
A

Usually not associated

46
Q
Chronic idiopathic (immune) thrombocytopenic purpura (ITP)
- Platelet count
A

Variable, 30,000-80,000/uL

47
Q
Chronic idiopathic (immune) thrombocytopenic purpura (ITP)
- Bleeding characteristics
A

Insidious

48
Q
Chronic idiopathic (immune) thrombocytopenic purpura (ITP)
- Occurrence of spontaneous remission
A

Relatively rare

49
Q
Chronic idiopathic (immune) thrombocytopenic purpura (ITP)
- Treatment
A
  • Treat w/ steroids

- Refractory cases may require splenectomy and/or chemotherapeutic agents

50
Q

Heparin-induced thrombocytopenia (HIT), type II, according to the basis for the possible thrombotic and hemorrhagic presentation

A
  • In HIT, PF4 and heparin combine to form a surface complex against which the IgG antibody is directed
  • Platelets become activated, in vivo platelet aggregation with thrombosis is possible → thrombotic and hemorrhagic problems
51
Q

An adverse effect of heparin therapy is called ____

A

Heparin-induced thrombocytopenia (HIT)

52
Q

Develops when the mother lacks a specific platelet-specific Ag that the fetus has inherited from the father

A

Neonatal alloimmune thrombocytopenia

53
Q

How do we get thrombocytopenia in neonatal?

A

Mother produces Abs to the fetal Ag which cross the placenta, and attach to the Ag-bearing fetal platelets, resulting in thrombocytopenia

54
Q

This is autosomal dominant inheritance and giant dohle-like bodies in neutrophils, eosinophils, basophils, and monocytes are seen

A

May-Hegglin anomaly

55
Q

4 clinical states in which thrombocytosis can be seen

A
  • Hemorrhage or surgery
  • Inflammation
  • Exercise-induced
  • FDA
56
Q

Describe thrombocytosis according to the etiology and the platelet count values

A
  • Etiology: reactive phenomena–secondary to hemorrhage or surgery, inflammation, exercise-induced, FDA???
  • Platelet count is ↑ but usually <1,000,000/cumm
57
Q

Describe thrombocythemia according to the etiology and the platelet count values

A
  • Etiology: MP disorder cause is unknown

- Platelet count exceeds 1,000,000/cumm