Abstract
Thrombocytopenia and thrombosis occurring as a direct consequence of heparin therapy are being recognized with increasing frequency in recent years. Current conceptions of the pathophysiology of this syndrome are explained, together with the mechanisms leading to the clinical features. The clinical spectrum of H.I.T.T.S. is widening, but there are diagnostic problems arising from a lack of awarenes of the syndrome by some practising clinicians. Many laboratory methods for detecting H.I.T.T.S. have been used, but particular attention should be given to the method of platelet aggregometry. Finally, problems encountered in diagnosis and management of this condition are discussed.