[Heparin-induced thrombocytopenia].

Abstract

Heparin-induced thrombocytopenia (HIT) is an adverse drug reaction that carries an increased risk of thromboembolic complications. HIT is caused by platelet-activating antibodies directed against a complex of platelet factor 4 (PF4) and heparin. HIT typically manifests in the second week after initiation of heparin therapy with a platelet count reduction of more than 50% of the highest level after the start of heparin administration as well as thromboembolic events. The clinical probability can be calculated by the 4 T's score. The laboratory diagnosis of HIT is based on confirmation of PF4/heparin antibodies or on functional tests that provide evidence of heparin-dependent platelet-activating antibodies. A low 4 T's score and negative HIT test virtually rule out the presence of HIT. Patients with acute HIT require anticoagulation with a compatible anticoagulant in a therapeutic dose. The drugs currently available for this include the direct thrombin inhibitors argatroban, lepirudin, bivalirudin, and desirudin and the indirect factor Xa inhibitors danaparoid and fondaparinux.

• Authors: T Thiele, K Althaus, A Greinacher
• Journal: Der Internist (Internist (Berl)) Vol. 51 Issue 9 Pg. 1127-32, 1134-5 (Sep 2010) ISSN: 1432-1289 [Electronic] Germany
• Vernacular Title: Heparininduzierte Thrombozytopenie.
• PMID: 20694716 (Publication Type: English Abstract, Journal Article, Review)

Chemical References

• Anticoagulants
• Autoantibodies
• Platelet Activating Factor
• Platelet Factor 4
• Heparin

Topics

• Acute Disease
• Anticoagulants (adverse effects, therapeutic use)
• Autoantibodies (blood)
• Heparin (adverse effects, therapeutic use)
• Humans
• Platelet Activating Factor (physiology)
• Platelet Count
• Platelet Factor 4 (immunology)
• Thrombocytopenia (chemically induced, immunology)