Heparin-induced thrombocytopenia risk factors: Difference between revisions
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{{CMG}}; '''Associate Editor | {{CMG}}; '''Associate Editor-In-Chief:''' {{CZ}}, Aric C. Hall, M.D., [mailto:achall@bidmc.harvard.edu] | ||
==Overview== | ==Overview== | ||
[[Heparin-induced thrombocytopenia]] is diagnosed when the [[platelet]] count falls by > 50% typically after 5-10 days of [[heparin]] therapy. | [[Heparin-induced thrombocytopenia]] is diagnosed when the [[platelet]] count falls by > 50% typically after 5-10 days of [[heparin]] therapy. | ||
Revision as of 17:55, 4 December 2011
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Heparin-induced thrombocytopenia |
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Differentiating Heparin-induced thrombocytopenia from other Diseases |
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Diagnosis |
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Treatment |
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Case Studies |
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Heparin-induced thrombocytopenia risk factors On the Web |
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American Roentgen Ray Society Images of Heparin-induced thrombocytopenia risk factors |
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Directions to Hospitals Treating Heparin-induced thrombocytopenia |
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Risk calculators and risk factors for Heparin-induced thrombocytopenia risk factors |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. [2], Aric C. Hall, M.D., [3]
Overview
Heparin-induced thrombocytopenia is diagnosed when the platelet count falls by > 50% typically after 5-10 days of heparin therapy. Genetic risk factors for thrombosis such as factor V Leiden, prothrombin gene mutation, methylenetetrahydrofolate reductase (MTHFR) polymorphism and platelet-receptor polymorphisms do not increase the risk of developing HIT associated thrombosis.
4 factors that affect the risk of developing HIT are noted as follows.[1] 1) Duration of heparin treatment; long duration, up to 2 weeks is associated with the greatest risk. 2) The type of heparin involved; UFH has a greater risk than LMWH. 3) The type of patient; surgical patients are at higher risk than medical; cardiac surgical patients have the highest risk of all. 4) Females have a higher risk.
CPB bypass: The management of cardiopulmonary bypass (CPB) patients with active HIT is controversial. Direct Thrombin Inhibitors such as agatroban and hirudin are used (and increase the aPTT in a dose dependent manner). However, in the large doses required for CPB hirudin's effects cannot be monitored well. Following CPB surgery the platelet count drops to about 40-60% of normal within the first 2-3 days postop due to hemodilution and platelet consumption. But there is also a risk of HIT. 20-50% of patients develop heparin antibodies during the first 5-10 days following CPB and some develop HIT (1-3% if UFH is continued through the postop period).
Reference
- ↑ Warkentin TE, Sheppard JA, Sigouin CS, Kohlmann T, Eichler P, Greinacher A. Gender imbalance and risk factor interactions in heparin-induced thrombocytopenia. Blood 2006;108:2937-41. PMID 16857993.