Updates to Heparin Induced Thrombocytopenia (HIT) ELISA Reporting and Management Algorithm, Tuesday, November 29, 2023

The University of Iowa Hospitals and Clinics (UIHC) has updated reporting of the HIT ELISA screening assay (HEPARIN INDUCED THROMBOCYTOPENIA (HIT) [LAB1088]) and subsequent management recommendations.

Reporting of the HIT ELISA screening assay now includes only the HIT ELISA optical density (OD), previously called Low Dose OD:

• OD results below 0.4 are considered Negative – HIT unlikely
• OD results between 0.4 – 1.0 are considered Equivocal – HIT possible but not likely, consult Hematology
• OD results between 1.0 – 2.0 are considered weakly Positive – HIT likely, order SEROTONIN RELEASE ASSAY, UNFRACTIONATED HEPARIN [LAB8585] to confirm
• OD results higher than 2.0 are considered strongly Positive – HIT very likely, SRA not indicated

These modifications were introduced by the Anticoagulation Task Force to align with recommendations from the American Society of Hematology and with internal studies evaluating the performance of the HIT ELISA screening assay for UIHC patients.

For more information, please consult the Clinical Care Guideline on PolicyTech CC.G.40, Heparin-Induced Thrombocytopenia (HIT) Diagnosis and Management Guideline Algorithm.

Questions regarding the HIT management algorithm should be directed to Hematology or Ryan Hobbs, Co-Chair of the Anticoagulation Task Force (356-2577, pager 4982, ryan-hobbs@uiowa.edu). Questions regarding HIT laboratory testing should be directed to Anna Merrill, Associate Director of Clinical Chemistry (678-8400, pager 7046, anna-merrill@uiowa.edu).