Heparin-induced thrombocytopenia in France, 1980-1998

Due to the extensive use of unfractionated heparins in France, there is considerable experience with heparin-induced thrombocytopenia (HIT). It is recommended that platelet counts be performed twice a week for three weeks when patients are treated with any form of heparin. A drop in platelet counts can, however, occur not only in HIT patients but also for other unrelated reasons. For diagnosing HIT, all laboratories in France use platelet aggregometry inspite of poor sensitivity. Both false positive and false negative results are obtained. The serotonin release test is not used in France. The ELISA test for HIT does not always correlate with the platelet aggregation test and many patients with a positive ELISA test do not necessarily have other evidence for HIT. This is especially true in patients following cardiopulmonary bypass surgery. None of the available laboratory tests reliably identify patients with HIT. Patients with HIT should not be managed with low-molecular-weight heparins, but danaparoid, argatroban and ancrod are viable options. Also, recombinant hirudin has been employed. All have advantages and disadvantages. At present, the diagnosis and management of patients with HIT remains difficult and properly designed clinical studies are needed to obtain answers to several open questions.