Platelet disorders Flashcards

1
Q

Bernard soulier clinical/lab features

A
  • Mild to moderate thrombocytopenia
  • large platelets
  • highly variable bleeding phenotype (mild to severe)
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2
Q

Bernard soulier diagnosis

A
  • platelet aggregometry.
  • BSS platelets do not agglutinate or aggregate in response to ristocetin
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3
Q

Bernard soulier management 1) non life threatening bleeding 2) critical bleeding

A

IF non life threatening bleeding, plt transfusion to goal 30k + antifibrinolytics
Critical bleeding - recombinant factor VIIa

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4
Q

Steps of platelet aggregation

A

3 A’s
1) Adhesion -adhesion to damaged epithelium. Adhere to collagen, Regulated by Gp1A2A, GP4, GP6
2) Activation ( release contents of alpha and dense granules)
3) Aggregation

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5
Q

Receptor that mediates platelet aggregation

A

GP2B3A receptor, and through fibrinogen

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6
Q

2 types of platelet granules and contents

A
  • alpha granules contain platelet factor 4, beta thromboglobulin, VWF, fibrinogen, Factor V, VIII, HMWK, albumin,
  • dense granules - ATP, ADP, calcium, serotonin, magnesium
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7
Q

PFA negative predictive value

A
  • very high (very good test of all steps of platelet function), essentially rules out platelet function defect
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8
Q

Bernard soulier inheritance pattern

A
  • autosomal recessive
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9
Q

1) Bernard soulier mechanism 2) complex that is deficient

A
  • *abnormal aggregation to ristocetin
  • lack of Gp1b/IX complex
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10
Q

General treatment of platelet disorders during acute bleeding episode

A
  • recombinant factor 7
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11
Q

What to be cautious about with platelet transfusion in bernard soulier

A

alloimmunization (antibodies to Gp1b)

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12
Q

1) grey platelet syndrome mechanism 2) name of gene mutation

A
  • lack of alpha granules secondary NBEAL2 gene mutation
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13
Q

grey platelet syndrome findings on periphearl smear

A
  • large platelets
  • platelets appear grey with poo granularity due to lack of alpha granules
    **see photo online
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14
Q

grey platelet syndrome sequela to know

A
  • predisposed to myelofibrosis
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15
Q

hermansky pudlak inheritance

A

autosomal recessive

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16
Q

hermansky pudlak demographics

A

Puerto rican (pocket of cases)

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17
Q

1) hermansky pudlak mechanism 2) name of gene mutation

A

Lack of dense granules, defect in HPS1 gene (hermansky pudlak)

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18
Q

hermansky pudlak and platelet studies

A
  • lack of second wave with ADP and epinephrine
  • dense granules or decreased on immunofluorescense
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19
Q

hermansky pudlak clinical features

A
  • pulmonary fibrosis
  • albinism
  • colitis
  • neurologic changes (nystagmus)
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20
Q

Quebec platelet disorder inheritance pattern

A

Autosomal dominant (so multiple family members affected)

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21
Q

Quebec platelet disorder mechanism

A
  • Decrease in alpha granule protein leading to abnormal aggregation w/ epinephrine
  • increased urokinase plasminogen (confirm)
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22
Q

Chediak higashi mechanism

A
  • mutation in LYST gene (lysosomal trafficking regulator protein)
    *platelet storage defect
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23
Q

Chediak higashi labs

A

*thrombocytopenia
anemia
neutropenia

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24
Q

Chediak higashi bone marrow biopsy finding

A

myeloperoxidase inclusion in neutrophils

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25
Q

Chediak higashi clinical features

A
  • immunodeficiences
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26
Q

Chediak higashi treatment

A
  • steroids
  • splenectomy
  • prophylactic antibiotics
  • consideration for transplant
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27
Q

1) glanzman’s thrombasthenia mechanism 2) response to ristocetin

A
  • platelet aggregation defect, abnormal aggregation to collagen and ADP
  • *lack of GPIIbIIIa receptor
  • no primary wave seen
  • normal aggregation to ristocetin
    (
    opposite to bernard soulier so important to remember)
28
Q

glanzman’s thrombasenia inheritance pattern

A

autosomal recessive

29
Q

Management of bleeding in glanzman’s thrombasenia

A

recombinant factor 7

30
Q

congenital afibrinogenemia lab features

A
  • prolonged PT + PTT
31
Q

Wiskott aldrich mechanism

A

WASP gene mutation

32
Q

Wiskott aldrich smear

A
  • small platelets
33
Q

Wiskott aldrich clinical features

A
  • ezcema
  • ## frequent infections
34
Q

Wiskott aldrich inheritance pattern

A
  • x linked recessive (thus more common in males)
35
Q

MYH9-RD inheritance pattern

A

autosomal dominant

36
Q

MYH9-RD lab features

A
  • large platelets
  • dohle bodies in neutrophils (see photo of smear online)
37
Q

MYH9-RD clinical features

A
  • cataracts
  • hearing loss
  • renal disease
38
Q

Bernard soulier labs

A
  • large platelets
  • mild thrombocytopenia
39
Q

What do alpha granules contain?

A
  • VWF
  • Fibrinogen
  • PF4
  • Growth factors: PDGF/TGF-Beta1
  • Factor V
40
Q

What do dense granules contain?

A
  • ADP/ATP
  • serotonin
  • calcium
41
Q

1) How do you look at dense granules? 2) platelet disorders with dense granule defects

A

Electron microscopy (far smaller than alpha granules you can see with light microscopy)
- need for Hermansky-Pudlak, Chediak-Higashi, Delta-storage pool disorders

42
Q

Utility of PFA

A
  • it’s a useful screening test
  • BUT has low sensitivity for platelet defects and can’t differentiate platelet disorders from VWD
43
Q

What is the gold standard for platelet function?

A

Platelet aggregometry

44
Q

What does platelet aggregometry curve show?

A
  • See photo on desktop
    *some labs x axis is flipped
45
Q

Glanzmann’s thrombasthenia on platelet aggreggation

A
  • absent aggregation to almost all antagonists (ADP, collagen, epinephrine) (think Glanzmann’s = global), only to ristocetin
    (Lack of GP11a/IIIb receptor leads to no binding of fibrinogen)
46
Q

What will you see on platelet aggregometry with Bernard-Soulier?

A
  • normal to ADP, collagen, epinephrine but flat curves/no response to ristocetin (lack of Ib/V/IX receptor complex leads to no binding of VWF)
47
Q

What does TEG look at?

A

determines interaction of fibrin, platelets, proteins in coagulation cascade using whole blood

48
Q

Next step if TEG looks like a test tube

A

Give platelets

49
Q

Next step if TEG looks like an upside down martini glass

A

Give TXA

50
Q

Next step if TEG looks like a champagne flute

A

Give cryo

51
Q

If photo shows electron microscopy, what should you be thinking?

A

dense granule problem

52
Q

For what platelet defects is flow cytometry useful for?

A

(surface GpIb, IX, Ia, IIa, IIb, IIIa - Bernard-Soulier, Glanzmann’s, Wiskott-Aldrich, collagen receptor defects)
Alpha and delta storage pool defects

53
Q

Hermansky Pudlak result on platelet aggregation

A
  • lack of secondary wave with ADP
54
Q

Bernard SOulier result on platelet aggregation

A
  • absent aggregation to ristocetin
55
Q

Other clinical clues to grey platelet syndrome

A
  • myelofibrosis
  • splenomegaly
  • moderate thrombocytopenia (though not all pts)
56
Q

Other clinical features of MYH9-RD

A
  • hearing loss
  • renal disease
  • cataracts
57
Q

What are the storage pool diseases?

A
  • Hermansky Pudlak
  • Chediak HIgashi
  • Grey platelet syndrome
  • Quebec platelet syndrome
58
Q

Grey platelet syndrome inheritance pattern

A
  • autosomal recessive
59
Q

Platelet aggregometry result with all the storage pool defects

A

lack of secondary wave to epinephrine (secondary wave driven by release of granule contents)

60
Q

RUNX1 related platelet disorder clinical features

A
  • variable thrombocytopenia
  • variable platelet dysfunction
  • AML risk
61
Q

Platelet disorder with highest risk of developing specific anti-platelet antibodies

A

Glanzmann’s thrombosthenia

62
Q

General treatment of platelet defect disorders

A
  • plt transfusion
  • antifibrinolytics
  • DDAVP
  • recombinant Factor VIIa
63
Q

Uremic platelet dysfunction management

A
  • dialysis
  • DDAVp
    *cryo
64
Q

What are the P2Y12 antagonists?

A
  • ticlopidinie
  • clopidogrel
  • prasugrel
65
Q

Clopidogrel associated with what condition?

A

TTP

66
Q

What are the IIB/IIIa inhibitors associated with?

A

Drug-induced thrombocytopenia (tirofiban and eptifibatide)

67
Q

Pathophys of MYH9-related disorder

A
  • defect of cytoplasmic structure and cell mobility due to mutation in nonmuscle myosin heavy chain IIA