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27 Cards in this Set
- Front
- Back
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how do inhibitors cause an increased PT & PTT?
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- acquired antibody against coagulation components
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when PTT & PT are normal what is often the cause of bleeding?
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- vWF --> b/c not measured, but it stabilizes FVIII
- if vWF:ag low enough or dysfunctional FVIII half life drops & prolongs PTT |
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what is a mixing study & how does it work?
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- mix pts plasma w/ normal plasma then repeat test to see if prolonged PT & PTT correct
- if test corrects 0-2 hrs = defective coagulation factors - if failure to correct after 2 hrs = circulating inhibitor protein |
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when it TT prolonged?
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- with abnormal fibrinogen or very low fibrinogen
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what are the two major functions of vWF?
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- adhesion of platelets to endothelium (primary hemostasis)
- stabilized FVIII in circulation = role in coagulation |
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what is Type I vWD?
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- AD, most mild, most common
- deficiency in functional vWF protein (aka low levels) |
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what is the problem in Type 2 vWF diseases? what is the most common?
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- problem is dysfunctional protein
- most common is type 2A |
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what happens in vWF disease 2B?
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- gain of function mutation (increased affinity for GPIb
- leads to thrombocytopenia & low vWF - reduction of highest MW multimers |
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what happens in vWF 2N? how do you distinguish it from FVIII deficiency?
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- mutation in binding site for FVIII
- moderate FVIII deficiency - poor response to FVIII concentrates, need to test binding site on vWF |
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what happens in vWF 2M?
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- vWF defect in binding to GPIb
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what happens in vWF type 3?
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- severe defiency/absence of vWF & low levels of FVIII b/c can't stabilize FVIII
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what is pseudo-VWD? which type of vWD does it mirror?
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- it is increased GPIb affinity for vWF (clearing multimers)
- mirrors type 2B but platelet abnormal! |
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what is acquired vWD?
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- usually autoimmune --> antibodies bind to vWF causing rapid clearance by RES
- can be due to hypothyroidism (decreased vWF) or cardiac (destruction of vWF in AS, MVP, etc) |
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what do PT & PTT look like in vWD? BT?
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- PT & PTT normal
- BT is prolonged - no matter what though if you think vWD need to do specific testing |
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when is FVIII low with vWD?
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- low if vWF low b/c it stabilized FVIII
- very low in type 2N when there is defect in FVIII binding even with normal vWF |
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what do you see on multimer analysis in type 3? type 1? type 2A & 2B?
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- see no vWF in type 3
- reduced levels in type 1 - loss of high weight multimers in type 2A & 2B |
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how do you tell the different b/w type 2B & pseudo-vWD?
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- defect in platelet in type 2B no in vWF
- do mixing study w/ pts platelets & see if there is still a problem - sequencing vWF exon 28 will reveal no mutation if it is pseudo-vWD |
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why do you use DDAVP (desmopressin) in vWD?
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- useful in type 1 because increases vWF levels
- doesn't really help in other types |
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what is hemophilia A vs B? which is more common?
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- A is FVIII deficiency (more common)
- B is FIX deficiency |
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what are target joints?
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- recurrent bleeding into joints can induce painful arthritis
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what is severe hemophilia? moderate? mild? very mild??
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- severe: <1% functional protein
- moderate: 1-5% levels - mild: 5-25% - very mild: 25-50% |
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what do the PT & PTT look like in hemophilia? what does a mixing study look like? what can a factor assay help with?
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- PT is normal
- PTT prolonged b/c FVIII & FIX are intrinsic factor pathways - mixing study will correct w/ normal plasma - factor assay can help quantify levels of FVIII & FIX |
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what do you prefer plasma derived or recombinant proteins? why?
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- prefer recombinant b/c no risk of infection like you have in plasma derived
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if someone has inhibitor in blood against FVIII how do you treat an acute hemorrhage? how do you eventually suppress the inhibitors?
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- Novoseven = recombinant FVIIa --> drives production of thrombin
- want desensitization |
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what is hemophilia C?
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- Factor XI deficiency
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what is acquired hemophilia?
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- autoantibody to FVIII
- treatment is immunosuppression |
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what do the labs look like in DIC? how do you treat it?
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- decreased platelets, decreased coagulation factors, decreased fibrinogen, increased d dimers
- prolonged PT & PTT - treat w/ platelet transfusion, factor replacement, frozen plasma - real treatment is to treat the underlying cause = deliver baby, antibiotics, etc |
