Heparin-Induced Thrombocytopenia (HIT) Antibodies, PF4 IgG/IgM/IgA by ELISA with Reflex to Serotonin Release Assay (Heparin Dependent Platelet Antibody), Unfractionated Heparin (INACTIVE as of 10/05/15: Refer to August 2015 Hot Line Test 2012181)
Ordering Recommendation
Semi-Quantitative Enzyme-Linked Immunosorbent Assay/Serotonin Release Assay
1-10 days
New York DOH Approval Status
This test is New York DOH approved.
Submit With Order
Specimen Required
Patient Preparation
Plain red or serum separator tube (SST). 
Specimen Preparation
Separate serum or plasma from cells ASAP or within 2 hours of collection. Transfer 3 mL serum to an ARUP Standard Transport Tube. (Min: 2 mL) Also acceptable: ACD or sodium citrated plasma. 
Storage/Transport Temperature
CRITICAL FROZEN. Separate specimens must be submitted when multiple tests are ordered. Ship on dry ice. 
Unacceptable Conditions
Heparinized specimens. 
After separation from cells: Ambient: Unacceptable; Refrigerated: 48 hours; Frozen: 1 month 
Reference Interval
Effective November 14, 2011
Test Number
Reference Interval
0051052Heparin-Induced Thrombocytopenia (HIT) Antibodies, PF4 IgG/IgM/IgA by ELISA (INACTIVE as of 10/05/15: Refer to August 2015 Hot Line Test 2012179)0.399 OD or less
2005631Serotonin Release Assay (Heparin Dependent Platelet Antibody), Unfractionated HeparinBy report

Interpretive Data
By itself, a positive result on this ELISA test is relatively non-specific for a clinical diagnosis of heparin-associated antibody syndrome (HIT) (frequent false-positives) and a negative result does not exclude a diagnosis of HIT if the clinical suspicion remains high (occasional false-negatives). Results should be used in conjunction with clinical findings, platelet counts and other laboratory results.

For a clinical scoring system to assess pretest probability of HIT and other guidance for diagnosing HIT, refer to the Heparin-Associated Antibody Syndrome topic at

Compliance Statement B: This test was developed and its performance characteristics determined by ARUP Laboratories. The U.S. Food and Drug Administration has not approved or cleared this test; however, FDA clearance or approval is not currently required for clinical use. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions.

Positive ELISA results are relatively non-specific for a clinical diagnosis of HIT. If ELISA result is positive, then Serotonin Release Assay (a functional assay with greater specificity for a clinical diagnosis of HIT syndrome) will be added. Additional charges apply. Microbially contaminated, heat-inactivated, hemolyzed, icteric, or lipemic sera may give inconsistent results.
CPT Code(s)
86022; if reflexed add 86022
Component Test Code*Component Chart NameLOINC
0051052Heparin-Induced Thrombocytopenia Abs PF434701-3
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
  • HAT
  • Heparin Induced Antibodies
  • Heparin PF4 Antibody
  • Heparin-Associated Antibody
  • HIPA
  • HIT Antibodies Reflex toSRA
  • HIT IgG, IgM, IgA and SRA
  • HIT PF4 Antibodies Reflex t SRA
  • HITA
  • Type II HIT