Heparin-Induced Thrombocytopenia (HIT) PF4 Antibody, IgG with Reflex to Serotonin Release Assay (Heparin Dependent Platelet Antibody), Unfractionated Heparin

Casandra

Casandra Test Code AR12474Version 1 (DRAFT)

Performing Lab

Lab ARUP LaboratoriesLab Test ID 2012181CPT Code 86022

Heparin-Induced Thrombocytopenia (HIT) PF4 Antibody, IgG with Reflex to Serotonin Release Assay (Heparin Dependent Platelet Antibody), Unfractionated Heparin

Clinical Use

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.

Test Details

New York Approved

Methodology

Immunoassay (ELISA)

Biomarkers

2 components

Heparin-Induced Thrombocytopenia PF4 Antibody, IgG • ELISASerotonin Release Assay • ELISA

LOINC Codes

Result Codes

73818-7

Result Turnaround Time

1-6 days

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.