Heparin-induced thrombocytopenia: Difference between revisions
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**Symptoms begin several days after heparin stopped | **Symptoms begin several days after heparin stopped | ||
**Severe thromboses | **Severe thromboses | ||
==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 | |||
==Treatment== | ==Treatment== | ||
#Discontinue all heparin products | #Discontinue all heparin products | ||
#Do not give platelts (may precipitate thrombosis) | #Do not give platelts (may precipitate thrombosis) | ||
#Start anticoagulation | #Start anticoagulation | ||
##Consider lepirudin (unless renal failure), argatroban (unless hepatobiliary disease), | ##Consider direct thrombin inhibitor [lepirudin (unless renal failure), argatroban (unless hepatobiliary disease), bivalirudin] or direct Xa inhibitor (fondaparinux, danaparoid) | ||
##Avoid warfarin until platelets > | ##Avoid warfarin until platelets >100K-150K | ||
==See Also== | ==See Also== | ||
Revision as of 17:16, 9 November 2013
Background
- Despite low plt count pt is actually hypercoagulable; bleeding is unusual
- Pathophysiology
- Pathologic activation / consumption of platelets due to Ab against heparin-plt complex
- Activated platelets then cause blood clot formation
- Platelet count falls b/c plts are bound in clots
- Can be caused by unfrationated or LMWH (10x common in the former)
- Occurs in 0.5-5% of pts tx'd w/ heparin
- Thrombosis occurs in 35-75% of pts; 20-30% die w/in 1 month
Clinical Features
- Typical
- Symptoms begin 5-10d after initiation of heparin
- >50% decrease in plt count (median nadir is ~60K; rarely <20K)
- DVT or PE
- Cerebral vein or adrenal vein thrombosis
- Limb arterial occlusion
- CVA
- MI
- Skin necrosis
- Symptoms begin 5-10d after initiation of heparin
- 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
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
See Also
Dispostion
- Admit
Source
Tintinalli