Heparin-induced thrombocytopenia and thrombosis: a potential fatal complication in a routine treatment.

Heparin-induced thrombocytopenia (HIT) is a severe complication of heparin therapy. Life-threatening thromboembolism (HITT) may occur in a large number of patients with HIT. In this article diagnostic problems and the clinical course of 4 typical patients are described. Diagnosis was based on the occurrence of thrombocytopenia during heparin therapy and was confirmed in vitro by an ELISA to heparin-platelet factor 4 antibodies, heparin-induced platelet activation assay (HIPAA) or the platelet aggregation assay (PAA). Thrombotic complications developed in 2 patients, one of whom suffered a fatal embolism after accidentally rechallenging with low-dose heparin which was used to maintain the patency of an intravascular catheter. After discontinuation of heparin the thrombocyte count rapidly increased to normal values during treatment with the heparinoid danaparoid (Orgaran) without complications.