Additional Thrombosis questions

Question 1

what does the mutation in prothrombin 20210A cause?

Answer 1

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

Question 2

For AT deficiency what is the risk of VTE?

Answer 2

always heterozygous, homozygous not compatible with life

risk of spontaneous VTE 40%, risk of recurrence. usually clot in the second decade of life

Question 3

what levels of protein C are associated with a risk of VTE?

Answer 3

levels below 50% (normal is 70-110%)

Question 4

what does UFH inhibit?

Answer 4

thrombin and factor Xa

Question 5

what is the antidote to UFH?

Answer 5

protamine sulfate

reverses the effect in 5 minutes

Question 6

what are the causes of heparin resistance?

Answer 6

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

Question 7

what does LMWH inhibit?

Answer 7

Xa more so than thrombin

Question 8

what is the antidote for LMWH

Answer 8

protamine sulfate, doesn’t work as well as for UFH

Question 9

how do you test for HIT?

Answer 9

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

Question 10

what is fondaparinux?

Answer 10

An indirect Xa inhibitor- high affinity binding to AT which induces a conformational change and increases the ability of AT to inactivate FXa

Question 11

what is argatroban and bivalrudin?

Answer 11

direct thrombin inhibitors
IV only
has no antidote

Question 12

what is dabigatran?

Answer 12

oral direct thrombin inhibitor, trade name pradaxa
no lab monitoring required
an antidote exists: idarucizumab (Praxbind)

other DOACs: Apixaban, rivaroxaban, edoxaban

Question 13

what effect does warfarin have on pregnancy?

Answer 13

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

Question 14

what is the INR?

Answer 14

ratio of the patients PT and the normal mean PT (at that lab)

Question 15

what is the antidote to warfarin?

Answer 15

Vit K

PCC and FFP can also be used

Question 16

why does warfarin skin necrosis happen?

Answer 16

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

Question 17

what are the indications for thrombolysis?

Answer 17

acute ischemia-limb threatening
intracardiac thrombus
PE-massive
Extensive DVT-SVC syndrome, occlusive IVC, bil renal vein clot with renal compromise, lg iliofemoral clot-risk of serious post-thrombotic syndrome

Question 18

what are the contraindications for thrombolysis?

Answer 18

active bleeding
surgery in the last 10 days
neurosurgery in the last 3 weeks
new stroke
potential for uncontrolled bleeding