Heparin-Induced Thrombocytopenia (HIT) PF4 Antibody, IgG with Reflex to Serotonin Release Assay (Heparin Dependent Platelet Antibody), Unfractionated Heparin
Gold standard reflex testing for confirming diagnosis of HIT. Serotonin Release Assay is performed for positive HIT Antibody, IgG.
Semi-Quantitative Enzyme-Linked Immunosorbent Assay/Serotonin Release Assay
Serum separator tube.
Separate from cells ASAP or within 2 hours of collection. Transfer 5.0 mL serum to an ARUP Standard Transport Tube. (Min: 2.0 mL)
CRITICAL FROZEN. Additional specimens must be submitted when multiple tests are ordered.
Ambient: Unacceptable; Refrigerated: 48 hours; Frozen: 2 years
|Test Number||Components||Reference Interval|
|2012179||Heparin-Induced Thrombocytopenia (HIT) PF4 Antibody, IgG||Less than or equal to 0.399 OD|
|2005631||Serotonin Release Assay (Heparin Dependent Platelet Antibody), Unfractionated Heparin||Negative|
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.
Laboratory Developed Test (LDT)
Microbially contaminated, heat-inactivated, hemolyzed, icteric, or lipemic sera may give inconsistent results. If Heparin-Induced Thrombocytopenia (HIT) PF4 Antibody, IgG is 0.400 O.D. or greater, Serotonin Release Assay (Heparin Dependent Platelet Antibody), Unfractionated Heparin is added. Additional charges apply.
86022; if reflexed, add 86022
|Component Test Code*||Component Chart Name||LOINC|
|2012180||Hep-Ind Thrombocytopenia PF4 Ab, IgG||73818-7|
- Heparin Induced Antibodies
- Heparin PF4 Antibody
- Heparin-Associated Antibody
- HIT Antibodies
- HIT IgG, IgM, IgA
- HIT PF4 Antibodies
- Type II HIT