Flashcards in Additional Thrombosis questions Deck (18):
what does the mutation in prothrombin 20210A cause?
causes abnormally high prothrombin levels and contributes to clot risk by increasing thrombin generation
VTE risk in heteros is 4x, with low risk of recurrence
homozygous form is very rare
For AT deficiency what is the risk of VTE?
always heterozygous, homozygous not compatible with life
risk of spontaneous VTE 40%, risk of recurrence. usually clot in the second decade of life
what levels of protein C are associated with a risk of VTE?
levels below 50% (normal is 70-110%)
what does UFH inhibit?
thrombin and factor Xa
what is the antidote to UFH?
reverses the effect in 5 minutes
what are the causes of heparin resistance?
AT deficiency (levels below 60%) inherited or acquired
Increased clearance-due to lasix or CVVH
high levels of FVIII or fibrinogen
increased heparin binding proteins
what does LMWH inhibit?
Xa more so than thrombin
what is the antidote for LMWH
protamine sulfate, doesn't work as well as for UFH
how do you test for HIT?
test for HIT antibodies using ELISA- this will look for all antibodies against heparin-PF4 complexes
confirmatory test is the functional assay-called serotonin release assay
what is fondaparinux?
An indirect Xa inhibitor- high affinity binding to AT which induces a conformational change and increases the ability of AT to inactivate FXa
what is argatroban and bivalrudin?
direct thrombin inhibitors
has no antidote
what is dabigatran?
oral direct thrombin inhibitor, trade name pradaxa
no lab monitoring required
an antidote exists: idarucizumab (Praxbind)
other DOACs: Apixaban, rivaroxaban, edoxaban
what effect does warfarin have on pregnancy?
between weeks 6-12 gestation it causes cartilage disease of nose and limb hypoplasia, intellectual disability
always remember to check for pregnancy before starting warfarin
what is the INR?
ratio of the patients PT and the normal mean PT (at that lab)
what is the antidote to warfarin?
PCC and FFP can also be used
why does warfarin skin necrosis happen?
protein C levels drop when warfarin is started, and this can potentiate clots, this is why you cover a patient with LMWH when getting warfarin therapeutic
what are the indications for thrombolysis?
acute ischemia-limb threatening
Extensive DVT-SVC syndrome, occlusive IVC, bil renal vein clot with renal compromise, lg iliofemoral clot-risk of serious post-thrombotic syndrome