COMPARISON OF PF4 HEPARIN ELISA ASSAY WITH THE C-14 SEROTONIN RELEASEASSAY IN THE DIAGNOSIS OF HEPARIN-INDUCED THROMBOCYTOPENIA/

The diagnosis of heparin-induced thrombocytopenia (HIT) may be affirme d by demonstrating heparin-dependent anti-platelet antibodies using th e C-14-serotonin release assay (SRA). In this study, results of the SR A was compared with the recently described platelet factor 4 (PF4)/hep arin enzyme-linked immunosorbent assay (ELISA). Compared with the SRA, the sensitivity and specificity of a PF4/heparin ELISA was 87% and 99 %, respectively, using an assay developed in our laboratory; and 90% a nd 98%, respectively, using a commercially developed kit (Diagnostica Stage, Asnieres, France). However, antibodies to PF4/heparin were also detected in up to 8% of patients whose plasma was negative by SRA, an d 23% of patients receiving heparin who were not thrombocytopenic, The se data indicate that results obtained with the PF4/heparin ELISA and the SRA are generally in accord in patients with a clinical diagnosis of HIT. However, discrepant results occur in approximately 20% of case s because of the greater sensitivity of ELISA and the possible involve ment of other heparin-binding proteins. The fact that each assay contr ibutes independent information in some cases must be considered in the sequence of test performance and in providing consultation to tile pr acticing hematologist.