||Heparin-induced thrombocytopenia (HIT) is a clinical diagnosis, supported by confirmatory laboratory testing. A combination of assessment of pre-test probability, ELISA and functional assays is required for accurate clinicopathologic diagnosis of HIT.
Stanford HIT panel includes: Heparin Platelet Factor 4 Antibody (test code: HITAB) and Heparin Induced Thrombocytopenia Functional Assay (test code: HITIA).
The sensitivity of the HIT antibody ELISA screen test is approximately 90%. Therefore, if the ELISA is negative, a HIT functional assay will not be performed.
The antibody ELISA screen for HIT PF4 antibodies is very sensitive for antibody detection, but relatively nonspecific for clinical HIT diagnosis. The specificity of positive functional tests for HIT diagnosis is believed to be high. If ELISA test is positive, a HIT functional assay will be performed.
In patients with a moderate to high clinical suspicion for HIT and negative ELISA, an HIT functional assay can be ordered as a stand-alone test (HITIA - in house, or SRA send-out).