[Heparin-induced thrombocytopenia. Diagnosis, clinical course and therapeutic alternatives].
Heparins are common and have been widely used in prophylaxis and therapy of thromboembolic disorders for many years. Nevertheless, the serious side effect of heparin-induced thrombocytopenia type II (HIT II) has attracted attention only recently. First evidence of HIT II is a drop in platelet count below 100,000/mm3. Subsequently, thromboembolic complications occur 6-20 days after beginning heparin therapy. Overall mortality is 20-30% of patients with HIT II. Therefore, frequent platelet counts are required for early diagnosis. However, in cases of moderate or absent thrombocytopenia the diagnosis of HIT II can be difficult. Laboratory tests such as heparin-induced platelet activation (HIPA) test or heparin/PF4-antibody-ELISA have limited sensitivity and specificity. Therefore, with typical clinical findings, divergent laboratory results should be interpreted with caution. If HIT II is suspected, all heparins should be discontinued immediately. Due to a high cross reactivity rate with the heparin-dependent antibody, subsequent therapy with low molecular weight heparins (LMWH) is contraindicated. As treatment of choice danaparoid or recombinant hirudin may be administered. Oral anticoagulation should be started cautiously with an alternative immediate-acting antithrombotic agent. More widespread use of LMWH may reduce the incidence of HIT II in the future. Nevertheless, the main and most important factor in the prevention of this life-threatening complication is the awareness and caution of the clinician.
Scheffold
N
N
Medizinische Klinik I, des Städtischen Krankenhauses Heilbronn.
Maitra
R
R
Cyran
J
J
D000925:Anticoagulants / Q000008:administration & dosage / Q000009:adverse effects*; D001780:Blood Coagulation Tests; D006493:Heparin / Q000008:administration & dosage / Q000009:adverse effects*; D006801:Humans; D010976:Platelet Count / Q000187:drug effects; D013921:Thrombocytopenia / Q000097:blood / Q000139:chemically induced* / Q000175:diagnosis; D013923:Thromboembolism / Q000097:blood / Q000188:drug therapy*
D000925:Anticoagulants; D006493:Heparin
Heparin-induzierte Thrombozytopenie. Diagnostik, klinischer Verlauf und therapeutische Alternativen.