Ordering Recommendation
Recommended initial screening test for heparin-PF4 antibodies that cause HIT. Confirmation with Serotonin Release Assay (Heparin Dependent Platelet Antibody), Unfractionated Heparin (2005631) may be necessary based on clinical presentation.
Mnemonic
Methodology
Semi-Quantitative Enzyme-Linked Immunosorbent Assay
Performed
Sun-Sat
Reported
1-2 days
New York DOH Approval Status
Specimen Required
Serum separator tube.
Separate from cells ASAP or within 2 hours of collection. Transfer 1 mL serum to an ARUP Standard Transport Tube. (Min: 0.2 mL)
CRITICAL FROZEN. Additional specimens must be submitted when multiple tests are ordered.
Heparinized specimens.
Ambient: Unacceptable; Refrigerated: 48 hours; Frozen: 2 years
Reference Interval
Less than or equal to 0.399 OD
Interpretive Data
This ELISA assay detects the presence of IgG antibodies to heparin-platelet factor 4 (PF4) complexes. Most cases of heparin-induced thrombocytopenia (HIT) are caused by IgG antibodies to heparin-PF4, rather than IgA or IgM antibodies. Negative results have a good negative predictive value for HIT, although rare false-negative results may occur. Positive ELISA results are sensitive but not completely specific for HIT. HIT is a clinicopathologic diagnosis. Clinical findings and the results of other laboratory tests must be taken into consideration. Higher optical density (OD) values in the IgG ELISA test correlate with a higher likelihood of positivity in platelet activation assays, such as the serotonin release assay (SRA), and an increased likelihood of clinical HIT.
A clinical scoring system to assess pretest probability of HIT along with other guidance for diagnosis is available in ARUP Consult®: https://www.arupconsult.com/content/heparin-induced-thrombocytopenia.
FDA
Note
Microbially contaminated, heat-inactivated, hemolyzed, icteric, or lipemic sera may give inconsistent results.
Hotline History
CPT Codes
86022
Components
Component Test Code* | Component Chart Name | LOINC |
---|---|---|
2012180 | Hep-Ind Thrombocytopenia PF4 Ab, IgG | 73818-7 |
Aliases
- HAT
- Heparin Induced Antibodies
- Heparin PF4 Antibody
- Heparin-Associated Antibody
- HIPA
- HIT Antibodies
- HIT IgG, IgM, IgA
- HIT PF4 Antibodies
- HITA
- Type II HIT