heparin-induced thrombocytopenia

(redirected from HIT syndrome)

heparin-induced thrombocytopenia

Acquired thrombocytopenia affecting some heparin-treated Pts–HTPs, defined as a ↓ platelet count during or shortly after heparin exposure; HIT is a markedly prothrombotic disorder seen in Pts who are at a high baseline risk for venous thrombosis DiffDx Antiphospholipid antibody syndrome, DIC, Trousseau syndrome–migratory thrombophlebitis & malignancy, TTP/HUS, thrombocytopenia and 'showers' of microthrombi Clinical HIT occurs 6-10 days after heparin exposure Diagnosis Aggregation studies using platelets from Pts known to be sensitive to antibody; quantification of serotonin release from platelets radiolabeled with serotonin in assay using Pt serum.

heparin-induced thrombocytopenia

Thrombocytopenia caused by an immune reaction to heparin. It may lead to widespread or potentially life-threatening blood clotting rather than bleeding. See: white-clot syndrome

CAUTION!

Patients whose platelet counts drop significantly during exposure to heparin should discontinue the drug immediately.

heparin-induced thrombocytopenia

A blood platelet deficiency disorder caused by a reaction to heparin. The condition is caused by antibodies, usually of the IgG class against a heparin-platelet factor IV complex on the surface of platelets. Paradoxically, the condition features thrombosis and embolism with the risk of stroke and other serious arterial occlusion effects. This is because the immune complexes formed combine with the antibody Fc receptors of platelets causing their activation and the initiation of clotting.
References in periodicals archive ?
This simple assay using a modern blood cell counter and based on the pathological mechanism of HIT syndrome shows great promise as a functional test for the laboratory diagnosis of HIT.
The clinical risk associated with HPF4 antibodies in patients who don't have HIT syndrome is poorly understood in clinical practice," stated David Kress, MD, leading study investigator and senior cardiothoracic surgeon at Aurora St.
HIT syndrome occurs in about 3% of the patients undergoing cardiac surgery and overt thrombosis occurs in 50% of HIT patients.
6,33] Although the thrombotic complications in HIT syndrome are well described, only limited data have become available on the inflammatory components in this disease.
67] These observations underscore the complex pathophysiology of HIT syndrome and suggest that there may be an HIT antibody active in a non-heparin-dependent manner.
It has been shown that the activation of platelets during the acute HIT syndrome is not fully controllable by anticoagulant medications.
HIT syndrome involves a decrease in circulating platelets (thrombocytopenia) and an increased tendency to form blood clots, which can have devastating clinical consequences such as limb ischemia requiring amputation (10-20%), myocardial infarction, stroke, pulmonary embolism and even death (20-30%).
HIT syndrome is an immune-mediated disorder associated with the use of heparin.
The initial focus of the collaboration is the commercialization of NOVASTAN as a treatment for HIT syndrome.