[Calcium heparin-induced immunologic thrombocytopenia complicated with venous gangrene of the legs. Report of a clinical case].

An 80-year-old woman was admitted to the Traumatologic Hospital of Florence because of bilateral post-traumatic humeral fractures. Subcutaneous calcium heparin was immediately administered to prevent deep venous thrombosis. Nine days later, the patient was referred to the Internal Medicine Unit because of severe immune-mediated heparin-induced thrombocytopenia and bilateral deep venous thrombosis. Heparin therapy was immediately discontinued, and the patient was switched to warfarin therapy. Diagnosis of heparin-induced thrombocytopenia was confirmed by positivity of anti-heparin-PF4 antibodies. On the second day of warfarin therapy, bilateral limb venous gangrene with a high risk of limb amputation appeared. To reduce thrombin generation, i.e., the mechanism by which heparin-induced thrombocytopenia induces thrombotic events, intravenous treatment with dermatan sulphate and low-dose urokinase was initiated. After 10 days of treatment, the limb venous gangrene disappeared, and low-dose warfarin therapy was again introduced. The patient was discharged 40 days after admission, and a Doppler ultrasound study showed only minimal signs of deep vein thrombosis in the right popliteal veins. Although in Italy the use of dermatan sulphate has been limited to the prevention of deep vein thrombosis, this case shows that it should be considered a useful agent for the treatment of thrombotic complications secondary to heparin-induced thrombocytopenia. Patients with acute immune-mediated heparin-induced thrombocytopenia should not be treated with warfarin alone. Frequent platelet count monitoring from day 5 of heparin treatment remains the best means of early detection of immune-mediated heparin-induced thrombocytopenia.