RBC II Putthoff, Bleeding Disorders from defective platelet functions Flashcards

1
Q

What are the classes of inherited disorders of platelet function

A

defects of adhesion
defects of aggregation
disorders of platelet secretion

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2
Q

What is Bernard Soulier syndrome

A

defective adhesion of platelets to subendothelial matrix

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3
Q

Where is the defect in Bernard Soulier

A

glycoprotein complex Ib-IX

R for vWF

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4
Q

What is disorder has bleeding from defective platelet aggregation

A

Glanzmann thrombasthenia

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5
Q

inheritance of glanzmann thrombasthenia

A

autosomal recessive

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6
Q

Where is the defect in glanzmann thrombasthenia

A

dysfunction of glycoprotein IIb IIIA

does not aggregate in response to ADP, collagen, epinephrine, thrombin

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7
Q

disorders of platelet secretion are chanracterized by what

A

defective release of certain mediators of platelet activation like thromboxane and ADP

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8
Q

what are the 2 significant types of acquired defects of platelet function

A

aspirin and NSAID caused

related to uremia

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9
Q

what activates fibrinogen to form clots

A

thrombin

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10
Q

What factors are involved in intrinsic clotting pathyway

A

XII XI IX
X
thrombin and fibrin

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11
Q

what factors are involved in extrinsic clotting pathway

A

VII TF
X
thrombin, fibrin

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12
Q

how do most patients with from coagulation factor defects present?

A

large post-traumatic ecchymoses or hematomas or prolonged bleeding

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13
Q

where are sites of bleeding from factor defect

A

GI and urinary tracts

weight bearing joints

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14
Q

What are the most common inherited disorders of coagulation pathway

A

VIII (hemophilia A)
IX (hemophilia B)
vWF

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15
Q

what is characteristic of acquired deficiencies of coagulation factors

A

multiple factors

decreased protein synthesis or shortened half life

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16
Q

vit K deficiency affects coagulation how

A

impaired synthesis of factors II, VII IX X and protein C

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17
Q

how does liver disease affect coagulation factors

A

many are made in the liver

18
Q

how are coagulation factors affected in DIC

A

multiple coagulation factors are consumed and deficient

19
Q

what cause single factor acquired deficiency

A

autoAb

very rare

20
Q

Where is factor VIII made

A

sinusoidal endothelial cells and kupffer cells in the liver

21
Q

where is vWF produced

A

endothelial cells and megakaryocytes

22
Q

what is the role of vWF

A

binds factor VIII and increases its circulation half life

promotes adhesion of platelets to subendothelial matrix thorugh GpIb-IX

23
Q

where is vWF stored

A

alpha granules of megakaryocyts

24
Q

what is the most common inherited bleeding disorder of humans in US

A

vWF disease

25
what are signs of vw disease
mild bleeding | spontaneous bleeding from mucous membranes, excessive wound bleeding or menorrhagia
26
what is inheritance pattern of vw disease
autosomal dominant but some are autosomal recessive
27
what else can vWF bind to besides VIII
GpIIb IIIa intefrins
28
how is vwF measured
ristocetin agglutination test | measured with aggregaometer
29
What types vw are assoc with quantitative defects in vwF
type I and III
30
characteristics type I VW disease
autosomal dominant | mild to mod deficiency
31
describe type III VW disease
autosomal recessive with very low levels vWF and severe manifestations
32
what causes type 3 VW disease
deletions or frameshift mutations involving both alleles
33
is type 2 VW disease characterized by quantitative or qualitative defects
qualitative
34
what is most common subtype type 2 VW disease
2A
35
inheritance 2A VW disease
autosomal dominant | missense mutations
36
how common is type 2 VW disease
25% of all cases assoc with mild-moderate bleeding
37
are platelet counts low in VW disease
no
38
what will vwD cause a deficiency in
factor VIII levels
39
are PT and PTT normal in vw D
prolonged PTT in type I and 3
40
what is Tx for mild vwD
desmospressin which stimulates vWF release | or infusions of VIII and vWF