Quiz: How much do you know about heparin-induced thrombocytopenia?
July 3, 2014, 12:01 pm
Heparin-induced thrombocytopenia. Lovecchio F. Clin Toxicol 2014 Jul;52:579-583.
This is a good up-to-date review of heparin-induced thrombocytopenia (HIT). The following are some questions based on the discussion in the paper (click on each question to reveal the answer):
Onset of HIT is generally within 5-10 days of heparin initiation, and is heralded by a 50% of greater decrease in the platelet count.
HIT occurs in 1-5% of patients receiving heparin. It is more frequently associated with use of unfractionated heparin as compared with low-molecular-weight heparin.
This is a trick question. HIT is a condition that causes clotting, not bleeding. This is a crucial point.
Heparin forms an immunogenic complex with platelet factor 4 (PF4). This complex attaches both to the surface of activated platelets and to endothelial cells, causing release of additional PF4, tissue factor, and other mediators that promote clotting.
- Immediately discontinue all heparin (including line flushes).
- Start a non-heparin agent for anticoagulation (if no contraindication)
- Start warfarin when thrombocytopenia resolves (platelet count > 150,000/mcL).
Because of increase risk of thrombosis, the authors recommend that these patient be anti coagulated for at least 3-6 months if the patient has had a thrombotic event, at least 2-3 months otherwise.