Heparin-induced thrombocytopenia: Difference between revisions
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==Background== | ==Background== | ||
*Pathologic activation / consumption of platelets due to antibodies against heparin- | *Pathologic activation / consumption of platelets due to antibodies against heparin-platelet 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. | *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) | *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> | *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 patients ; 20-30% die within 1 month<ref name="Lovecchio"></ref> | ||
===Type 1 HIT=== | |||
Occurs within the first 48 hours after heparin use with an initial drop in platelet count due to direct effect of heparin on platelet activation. The platelet count normalizes in a few days with continued heparin treatment. | |||
===Type 2 HIT=== | |||
An immune-mediated process which typically occurs 5-10 days after exposure to heparin complicated by thrombosis. | |||
==Clinical Features== | ==Clinical Features== | ||
;Symptoms usually begin 5-10 days after initiation of heparin or can begin within hours if there are already preexisting circulating antibody from prior sensitization | |||
===Delayed Symptoms=== | |||
*>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 | |||
===Immediate Symptoms=== | |||
*Flushing | |||
*Tachycardia | |||
*[[Hypotension]] | |||
*[[Dyspnea]] | |||
* | |||
* | |||
==DDX== | ==DDX== | ||
| Line 34: | Line 34: | ||
==Diagnosis== | ==Diagnosis== | ||
*Serotonin release assay (SRA) = gold standard | *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 with no heparin based compound such as a 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== | ==Dispostion== | ||
*Admit | *Admit to medicine with a hematology consult | ||
==See Also== | ==See Also== | ||
Revision as of 21:16, 5 July 2014
Background
- Pathologic activation / consumption of platelets due to antibodies against heparin-platelet 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]
Type 1 HIT
Occurs within the first 48 hours after heparin use with an initial drop in platelet count due to direct effect of heparin on platelet activation. The platelet count normalizes in a few days with continued heparin treatment.
Type 2 HIT
An immune-mediated process which typically occurs 5-10 days after exposure to heparin complicated by thrombosis.
Clinical Features
- Symptoms usually begin 5-10 days after initiation of heparin or can begin within hours if there are already preexisting circulating antibody from prior sensitization
Delayed Symptoms
- >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
Immediate Symptoms
- Flushing
- Tachycardia
- Hypotension
- Dyspnea
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
Treatment
- Discontinue all heparin products
- Do not give platelts (may precipitate thrombosis)
- Start anticoagulation with no heparin based compound such as a 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 to medicine with a hematology consult