PF4 ENHANCED assay for the diagnosis of heparin-induced thrombocytopenia in complex medical and surgical patients

Objective: To evaluate the sensitivity and specificity of the PF4 ENHANCED (GTI Diagnostics, Waukesha, WI) enzyme-linked immunosorbent assay for heparin-induced thrombocytopenia using the carbon-14 serotonin-release assay as the reference method. Design: A total of 34 patients were prospectively enrolled with a variety of diagnoses and suspected heparin-induced thrombocytopenia. They were clinically scored and underwent testing with the C-14-serotonin-release assay. Enzyme-linked immunosorbent assay and C-14-serotonin-release assay results were also available from 21 medical and surgical patients who had previously been tested. Main Results: With the 14 C-serotonin-release assay as the reference method, the sensitivity and specificity of the enzyme-linked immunosorbent assay were 93% and 65%, respectively. There was only one false-negative enzyme-linked immunosorbent assay. The clinical scores were frequently misleading, largely because of difficulty excluding other causes of thrombocytopenia. Conclusion: Because of its high sensitivity, we believe the PF4 ENHANCED enzyme-linked immunosorbent assay should be used to identify heparin-induced thrombocytopenia in patients with multiple potential causes of thrombocytopenia, although false-positive results will not be uncommon.