Heparin-induced thrombocytopenia in the ICU: an overview

Heparin, a negatively charged glycosaminoglycan (3,000-30,000 Da), is an anticoagulant released by mast cells and basophils during the normal clotting process [ 1 ]. Heparin is widely used for the treatment and prophylaxis of thromboembolic diseases in medical and surgical patients [ 1 ]. Heparin-induced thrombocytopenia (HIT) is one of the most serious adverse events associated with this drug. HIT is an immune-mediated, prothrombotic complication that occurs with unfractionated heparin (UFH) and to a lesser extent with low-molecular-weight heparin (LMWH) [ 2 ]. The fundamental paradox of HIT results from a platelet-activating immune response triggered by the interaction of heparin with a specific platelet protein, platelet factor 4 (PF4) [ 3 ].