Heparin-induced thrombocytopenia - Minimising the risks in the elderly patient

Heparin therapy may sometimes be seriously complicated by heparin-induced t hrombocytopenia (HIT). Heparin use for treatment and prevention of thromboe mbolism is more common in the elderly and that may be the reason why HIT is reported more frequently in this group of patients. The first approach in the management of HIT is awareness of this disorder. The morbidity and mort ality associated with HIT may be reduced by avoiding unnecessary heparin ex posure, by reducing the duration of heparinisation and by using low molecul ar weight heparins rather than unfractionated heparin. A decrease from base line values of at least 30% in the platelet count, any unexplained thrombot ic event and the finding of a white clot at thrombectomy are clinical warni ng signs that should alert physicians to a possible diagnosis of HIT. Indee d, early clinical recognition of HIT may sometimes prevent the severe compl ications associated with this disorder. Objective confirmation of the diagn osis of HIT is difficult because none of the available biological tests pos sess 100% sensitivity or 100% specificity. It is, however, possible to opti mise the performances of the functional assay, mainly the platelet aggregat ion test (PAT), by following the manoeuvres described by different investig ators. The use of 2 classes of assay (functional and antigen assays) and re peat testing on another day can avoid misdiagnosis of HIT. An alternative p arenteral anticoagulant treatment is most often mandatory after heparin wit hdrawal. Danaparoid sodium and lepirudin are 2 drugs that are currently ava ilable for the treatment of HIT, and the efficacy of argatroban needs to be confirmed in greater numbers of patients with HIT. The use of these drugs has contributed to the reduction in the mortality and morbidity associated with HIT.