Heparin-Induced Thrombocytopenia (HIT) PF4 Antibody, IgG with Reflex to Serotonin Release Assay (Heparin Dependent Platelet Antibody), Unfractionated Heparin
Use
This test is used for the confirmation of heparin-induced thrombocytopenia (HIT), which is a serious immune-mediated adverse reaction to heparin. It involves the formation of antibodies (primarily IgG) that activate platelets, which can cause thrombocytopenia and an increased risk of thrombosis. The initial ELISA assay detects IgG antibodies to heparin-PF4 complexes. Positive results are followed up with a serotonin release assay as the confirmatory test. This reflex approach ensures high sensitivity and specificity for diagnosing HIT.
Special Instructions
The test is performed daily from Sunday to Saturday. It is critical to freeze the specimen immediately after separation from cells. If the initial ELISA result is 0.400 O.D. or greater, a serotonin release assay is automatically added, incurring additional charges.
Limitations
The ELISA assay, while sensitive, is not fully specific, meaning false positives can occur. False negatives are rare but possible. The diagnosis of HIT is clinical and relies on a combination of lab results, clinical scoring, and symptoms. The presence of IgG antibodies must be correlated with clinical findings as higher optical density (OD) values are associated with increased positivity in the confirmatory serotonin release assay and the clinical diagnosis of HIT.
New York Approved
Methodology
Immunoassay (ELISA)
Biomarkers
LOINC Codes
- 73818-7
Result Turnaround Time
1-6 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
5.0 mL
Minimum Volume
2.0 mL
Container
Serum separator tube
Collection Instructions
Collect the serum using a serum separator tube. Separate from cells as soon as possible or within 2 hours of collection. Transfer the serum to an ARUP Standard Transport Tube.
Storage Instructions
Store and transport the specimen in a frozen state.
Causes for Rejection
Heparinized specimens, microbially contaminated, heat-inactivated, hemolyzed, icteric, or lipemic sera may give inconsistent results.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | Unacceptable |
| Refrigerated | 48 hours |
| Frozen | 2 years |