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IBI Test 4 > B3.068 Big Case Hemophilia > Flashcards

B3.068 Big Case Hemophilia Flashcards

1
Q

functional elements of hemostasis

A 
vascular wall (endothelium and subendothelial collagen)
platelets
von Willebrand factor
coagulation factors
calcium
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2
Q

result of primary hemostasis

A

platelet plug

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3
Q

result of secondary hemostasis

A

fibrin meshwork stabilized by cross-linking

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4
Q

which clotting factors does thrombin stimulate in a positive feed back mechanism

A

11, 8a, 5a

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5
Q

PT factors

A

TF (thromboplastin) , 7, common

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6
Q

PTT factors

A

prekallikren, HMWK, 12, 11, 9, 8, common

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7
Q

common factors

A

10, 5, 2 (prothrombin), 1 (fibrinogen)

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8
Q

bleeding patterns associated with disorders of primary hemostasis

A

skin or mucosal bleeds
purpura, petechiae, ecchymosis
spontaneous bleeding

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9
Q

bleeding patterns associated with secondary hemostasis

A

bleeds into soft tissue, muscle, joints
hemarthrosis
bleeding with trauma

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10
Q

two classes of common acquired disorders of secondary hemostasis

A

acquired factor deficiencies

factor inhibitors

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11
Q

3 causes of acquired factor deficiencies

A

liver disease
DIC
vitamin K deficiency - includes warfarin therapy

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12
Q

why does liver disease cause factor deficiencies?

A

many coagulation factors are produced in the liver

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13
Q

which factor is one of the easiest to monitor for deficiencies?

A

factor 7
shortest half life
is the first to deplete and usually has the most significant depletion
goes up and down the most

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14
Q

which factors are vitamin K dependent?

A

2, 7, 9, 10

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15
Q

3 factor inhibitory conditions

A

lupus anticoagulant
heparin therapy
specific factor inhibitors
-associated with treatment of factor deficiencies
-associated with autoimmune or lymphoproliferative disorders

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16
Q

what is lupus anticoagulant and why is it a misnomer

A

autoantibody associated with increased PT, PTT
NOT associated with lupus directly
NOT associated with anticoagulant activity in vivo

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17
Q

which factors are inhibited by heparin

A

factor 10, 2

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18
Q

whats more common, acquired or inherited disorders of secondary hemostasis?

A

acquired more common

inherited super uncommon

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19
Q

most clinically relevant inherited disorder of secondary hemostasis

A

factor 8 or factor 9 deficiency

Hemophilia A and B respectively

20
Q

what is interesting about factor 12, HMWK, and prekallikrein deficiencies?

A

no clinical relevance
discover through lab abnormalities, but have no legitimate risk for bleeding
patients just need to be aware to tell their clinicians

21
Q

where is factor 8 made

A

liver

22
Q

factor 8 half life

A

2.4 hours

12 hours if bound to vWF

23
Q

how do you measure factor 8 function?

A

PTT- screen

F8 activity- based on clotting assay using F8 deficient reagent (mixing study)

24
Q

where is vWf made

A

endothelial cells and platelets

25
Q

how do you measure vWf?

A

PFA-100 - screen
vWf antigen- quantity
vWf activity (ristocetin cofactor activity)- quality

26
Q

what is hemophilia

A

decreased factor 8 (A, 80%)

decreased factor 9 (B, 20%)

27
Q

genetics of hemophilia

A

X-linked - males affected, females carriers
no family history in 30%- new mutations
>500 mutations
large gene deletions/insertions associated with most symptoms

28
Q

clinical manifestations of hemophilia

A

spontaneous or traumatic bleeding into, soft tissue, muscle
life threatening bleeding (CNS, oropharyngeal space, retroperitoneal space)
self limited hematuria
contractures, joint deformities secondary to hemarthrosis

29
Q

why is bleeding into the oropharyngeal space so dangerous

A

can quickly compromise airway

30
Q

laboratory diagnosis of hemophilia

A 
prolonged PTT (extent of prolongation doesn't correlate with factor level)
decreased factor 8 or 9 level (only way to distinguish A from B)
31
Q

discuss how disease severity varies with residual factor levels

A

severe <1%
moderate 1-5%
mild 6-30%

32
Q

treatment of hemophilia

A 
factor 8 or 9 concentrates
-recombinant human (or bovine or porcine)
supportive therapy
-DDAVP
-antifibrinolytic agents
33
Q

what should you NEVER do to treat hemophilia?

A

use blood products like cryoprecipitate

can get HIV or HCV (leading cause of death in hemophilia patients)

34
Q

what does DDAVP do

A

forces platelets and endothelial cells to release vWF

stabilizes more factor 8

35
Q

why do antifibrinolytic agents help with hemophilia

A

stop breakdown of clots do you have more available fibrin to help with clot formation

36
Q

factor 8 concentrate dose calculation

A

1 unit/kg body weight increases level by 2%
dose = (target level - baseline) * body weight * 0.5 (unit/kg)
dose twice daily

37
Q

factor 9 concentrate dose calculation

A

1 unit/kg body weight increases level by 1%
dose = (target level - baseline) * body weight * 1 (unit/kg)
dose once daily

38
Q

target factor levels for hemophilia treatment

A

primary prophylaxis - 1%
surgical prophylaxis - 100% for 7-10 days tapered based on likelihood of bleeding
mild bleeding- 30-50% for several days
severe bleeding- 100% for several days

39
Q

why might your body develop antibodies to factor 8 or 9?

A

if you have hemophilia and get these factors transfused, your body might recognize them as foreign and attack them

40
Q

incidence of Abs to F8 or F9

A

hemophilia A- 5-10% of all cases; 20% of severe cases

hemophilia B- 3-5% of all cases

41
Q

risk factors for Abs to F8 or F9

A 
severe deficiency (<1% factor level)
family history of inhibitor
African descent
large deletions or rearrangements of gene
intensive therapy
42
Q

lab tests for detecting Abs to F8 or F9

A

PTT 1:1 mixing study

Bethesda assay- 1 BU = amount on inhibitor that neutralizes 50% factor activity at 2 h

43
Q

discuss results of the Bethesda assay and their clinical implications

A

low responder <5 BU : treated by upping dose

high responder >10 BU : have to use bypass agents to treat

44
Q

management of acute bleeding in people with Abs to F8 or F9

A

low responders - high dose recombinant human or porcine factor concentrate
high responders - bypass agents

45
Q

how to reduce Abs to F8 or F9

A

immune tolerance induction

immunosuppression, anti-CD20 - variable effectiveness

IBI Test 4 (21 decks)

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