Heparin-associated thrombocytopenia (HAT)--still a diagnostic and therapeutical problem in clinical practice.

Type II of heparin-associated thrombocytopenia (HAT) is well known, but the cardinal symptom, thrombocytopenia, is rarely adequately considered. Serious and potential lethal complications such as pulmonary embolism, cerebral stroke, or limb gangrene are often falsely regarded as insufficient anticoagulation. Guided diagnosis and therapy are of vital importance for the patient's outcome. Based on the experience of patients with HAT Type II treated in the intensive care unit, a diagnostic and therapeutic approach to the cardinal symptom thrombocytopenia is presented. A recently developed heparin-induced platelet activation assay (HIPAA) seems to be a highly sensitive laboratory test. The first therapeutic principle in case of presumed and diagnosed HAT is the cessation of unfractioned or low-molecular-weight heparins. ORG 10172 (Orgaran), a low-sulfated heparinoid with a low cross-reactivity (10%) to heparins, can be regarded as the most effective anticoagulant in patients with HAT Type II.