Heparin-induced thrombocytopenia: Difference between revisions
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==Background== | ==Background== | ||
*Pathologic activation / consumption of platelets due to antibodies against heparin-plt complex | |||
*Despite the low platelet count, the patient is actually hyper coagulable and bleeding is unusual. The activated platelets cause blood clot formation and the platelet count falls because the platelets are bound in clots. | |||
*Can be caused by unfrationated or LMWH (10x common in the former) | |||
* | *Occurs in 0.5-5% of patients treated with heparin<ref name="Lovecchio"> Lovecchio F. Heparin-induced thrombocytopenia. Clin Toxicol (Phila). 2014 Jul;52(6):579-83</ref> | ||
*Thrombosis occurs in 35-75% of patients ; 20-30% die within 1 month<ref name="Lovecchio"></ref> | |||
*Thrombosis occurs in 35-75% of | |||
==Clinical Features== | ==Clinical Features== | ||
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==Source== | ==Source== | ||
<references/> | |||
[[Category:Heme/Onc]] | [[Category:Heme/Onc]] |
Revision as of 12:34, 4 July 2014
Background
- Pathologic activation / consumption of platelets due to antibodies against heparin-plt complex
- Despite the low platelet count, the patient is actually hyper coagulable and bleeding is unusual. The activated platelets cause blood clot formation and the platelet count falls because the platelets are bound in clots.
- Can be caused by unfrationated or LMWH (10x common in the former)
- Occurs in 0.5-5% of patients treated with heparin[1]
- Thrombosis occurs in 35-75% of patients ; 20-30% die within 1 month[1]
Clinical Features
- Typical
- Rapid onset
- Symptoms begin within hours of initiation of heparin
- Due to preexisting circulating antibody from sensitization several weeks earlier
- Sudden drop in plt count
- Thrombosis
- Flushing
- Tachycardia
- Hypotension
- Dyspnea
- Symptoms begin within hours of initiation of heparin
- Delayed onset
- Symptoms begin several days after heparin stopped
- Severe thromboses
DDX
Diagnosis
- Serotonin release assay (SRA) = gold standard
- Positivity determined by optical density (OD) reported w/ assay (same concept as a titer)
- OD <1 = <5% chance of HIT
- OD 1.4 = 50% chance of HIT
- OD >2 = 90% chance of HIT
- Positivity determined by optical density (OD) reported w/ assay (same concept as a titer)
Treatment
- Discontinue all heparin products
- Do not give platelts (may precipitate thrombosis)
- Start anticoagulation
- Consider direct thrombin inhibitor [lepirudin (unless renal failure), argatroban (unless hepatobiliary disease), bivalirudin] or direct Xa inhibitor (fondaparinux, danaparoid)
- Avoid warfarin until platelets >100K-150K
Dispostion
- Admit