Q: 44 year obese male admitted with PE is now on Heparin and transitioniing to warfarin therapy. On 9th day of treatment, patient is diagnosed with HIT (Heparin induced Thrombocytopenia) with platelet count of 72. INR is reported to be 2.9. What would be your next step beside stopping Heparin?

Answer: Stop Warfarin and  reverse Warfarin effect with Vitamin K.

There is a very high risk of warfarin necrosis in people with HIT who have low platelet counts. Warfarin, should not be used in HIT until the platelet count is at least 150 x 10^9/L. Warfarin necrosis is marked by skin gangrenes. If the patient was receiving warfarin at the time when HIT is diagnosed, the activity of warfarin should be reversed with vitamin K.

Another important decision to make is need of use of 'direct thrombin inhibitors'.