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Clinical presentation and diagnosis of heparin-induced thrombocytopenia

Steven Coutre, MD
Section Editor
Lawrence LK Leung, MD
Deputy Editor
Jennifer S Tirnauer, MD


Heparin-induced thrombocytopenia (HIT) is a life-threatening complication of exposure to heparin (ie, unfractionated heparin, low molecular weight [LMW] heparin) that occurs in up to 5 percent of patients exposed, regardless of the dose, schedule, or route of administration.

HIT results from an autoantibody directed against endogenous platelet factor 4 (PF4) in complex with heparin. This antibody activates platelets and can cause catastrophic arterial and venous thrombosis with a mortality rate as high as 20 percent; although, more recently with improved recognition and early intervention, these rates have been reported as below 2 percent. In those suspected of having HIT based on clinical grounds, all exposure to heparin should be eliminated immediately and a non-heparin anticoagulant should be administered until a complete diagnosis can be made.

The clinical presentation and diagnosis of HIT will be discussed here. The management of HIT and the use of heparin and alternative anticoagulants are discussed separately.

(See "Management of heparin-induced thrombocytopenia".)

(See "Heparin and LMW heparin: Dosing and adverse effects".)

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Literature review current through: Nov 2017. | This topic last updated: Nov 03, 2017.
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