Pediatric Hematolgy: VWD
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- what is the relationship between VW factor and blood type
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lowest levels with type O
highest levels with AB - what is the defect in VWD type 2B
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dominant GAIN of function
the HMW mulitmers bind spontaneously to platelets and are subsequently removed from the circulation (which is why there can be thrombocytopenia with this type) - what is the difference in pathophysiology between type 1 and type 2 vWD
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type 1: quantitative
type 2: qualitative - what differentiates type 2 A vWD from type 2b on aggregation studies
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2A - get virtually no aggultination with ristocetin
2B get increased agglutination comared to normal - what treatment is contraindicated in type 2B vWD
- DDAVP
- lab findings in type 1 vWD
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normal PT, PTT, platelets
vWF antigen, ristocetin cofactor and f8 all tend to be decreased in parallel - treatment for type 2a vWD
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DDAVP
clotting factor concentrates containing f8 and vwf (but not cryo b/c no viral inactivation) - why is DDAVP contraindicated in type 2B vWD
- DDAVP causes the release of additonal vWF which is then spontaneously bound to platelets and cleared from the system - worsening the thrombycytopenia
- what is the treatment for type 2B vWD
- clotting factor concentrates containing both f8 and vWF
- what is the defect in type 2N vWD
- vWF molecule does not bind factor 8
- which types of vWD have decreased levels of F8
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type 2N
in this type VWF does not bind F8 and the unbound F8 is rapidly cleared from the system
type 3 - levels are virtually undetactable - potential misdiagnosis in type 2N vWD
- hemophilia
- who gets type 2N vWD
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compund heterozygotes with type 1 VWD or
recessive inheritance - what is the defect in type 2M vWD
- abnormal binding site on vWF for platelet GP Ib resulting in reduced ristocetin cofactor activity
- how does type 2M vWD differ from other type 2s in terms of multimeric pattern
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normal multimeric pattern
(other type 2s have decreased large size multimers) - what are the lab findings in type 3 vWD
- virtually no detectable vWF:Ag and markedly decreased f8