Question 15

Question:

A 49 year old male is being treated for a PE. On the 6th day of hospitalization, he is found to have a platelet count of 69000/mm3. Heparin therapy is stopped immediately to prevent which of the following complications?

Correct Answer: A. Arterial thrombosis

This patient likely has heparin-induced thrombocytopenia (HIT). Even though the platelet absolute count is lowered, HIT paradoxically causes more thrombosis than bleeding. HIT occurs when antibodies form to heparin and platelet factor IV. The antibody reacts by attaching to Fc receptors on platelets, which in turn causes platelet activation.
The typical presentation of HIT is a fall of platelet counts more than 50% in 5-10 days after initiation of heparin. The patient may present with widespread ischemic features. Discontinuation of heparin and treatment with direct thrombin inhibitors like argatroban and lepirudin is recommended.