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Heparin-PF4 antibody (HIT) w/reflex to SRA

Lab Section:  Immunology  
Lab Location:  Main Lab
Test ID: LAB7878 
Methodology: Enzyme-Linked Immunosorbent Assay (ELISA)
Schedule: Monday, Thursday
Reported: 3 days
Specimen Requirements:  Collection: 4.0 mL Blood in a Red Top Tube.
Pediatric volume: 1.0 mL.
The presence of circulating heparin may interfere with the assay creating the potential for a false negative result. Therefore, it is strongly recommended that specimen collection occur a minimum of 4 hours after ceasing heparin therapy.
Unacceptable conditions: Samples collected in gel-barrier tubes
Stability: After separation from cells: Refrigerated: 2 days; Frozen: 1 year

Notes: 

Reflex Criteria: All equivocal and positive samples will reflex the SRA that will be performed at a reference laboratory.

Clinical Indications: For the evaluation of possible immune-mediated heparin induced thrombocytopenia (HIT), which should be suspected for the following patients: Patients not previously exposed to heparin, the development of absolute thrombocytopenia or decrease in platelet count of > or =50% from baseline or postoperative peak with the onset of thrombocytopenia beginning approximately 5 to 10 days after initiation of heparin. This may or may not be associated with new or progressive thrombosis in patients treated with heparin. Patients previously exposed to heparin (especially within the preceding 100 days), in addition to the above findings, the onset of thrombocytopenia could occur within 24 to 48 hours after reexposure to heparin. In patients with prior suspected or documented heparin-induced thrombocytopenia (HIT), with or without thrombosis, assay for presence of H/PF4 antibody may be useful in assessment of the risk of recurrence of HIT with additional exposure to heparin, however, prospective data are limited.

Reference Interval:  Reference Interval: 
       <0.400 = Negative 
        0.400-0.600 = Weak Positive 
       >0.600 = Positive
Tests in this Panel: 
Test NameReference Interval
HIT Antibody, OD [LRR20693]
Age Limit Sex Normal Range
0 Days - 999 Years Any <0.400
HIT Antibody, Interpretation [LRR13989]
Age Limit Sex Normal Range
0 Days - 999 Years Any Negative
CPT Code(s): 86022
Last Changed: 01/19/2017 08:35:39
Last Reviewed: 01/05/2017 15:08:04