Serologic results in >1000 patients with suspected heparin-induced thrombocytopenia.
Heparin-induced thrombocytopenia (HIT) can lead to life-threatening and limb-threatening thrombosis. HIT is thought to be initiated by the interaction of pathogenic antibodies toward a complex platelet factor 4 (PF4) and heparin (PF4:H), which can activate platelets and predispose to thrombosis. As such, the laboratory diagnosis of HIT includes antigenic and functional assays to detect antibodies directed at PF4:H complexes. We performed a retrospective analysis of 1017 consecutive samples tested by serotonin-release assay and by enzyme-linked immunosorbent assay (ELISA). Most samples showed no serologic evidence of HIT, whereas 4% to 5% of samples demonstrated both antigenic and functional serological evidence for HIT. Approximately 12% to 18% of samples showed immunologic evidence of anti-PF4:H antibodies but without functional evidence of serotonin release in vitro. Interestingly, a small minority of samples (0.7%) caused serotonin release but were negative in the ELISA. The results are presented using cutoff values established at our hospital and for the ELISA manufacturer. This study provides a pretest probability of the serologic results from an antigenic assay (ELISA) and a functional assay (serotonin-release assay) in patients clinically suspected of having HIT.
Shelat
Suresh G
SG
Children's Hospital of Philadelphia, 3615 Civic Center Boulevard, Philadelphia, PA 19104, USA. shelat@mail.med.upenn.edu
Tomaski
Anne
A
Pollak
Eleanor S
ES
D000906:Antibodies / Q000097:blood; D000925:Anticoagulants / Q000009:adverse effects*; D004797:Enzyme-Linked Immunosorbent Assay; D006493:Heparin / Q000009:adverse effects*; D006801:Humans; D010978:Platelet Factor 4 / Q000276:immunology; D012701:Serotonin / Q000378:metabolism; D013921:Thrombocytopenia / Q000139:chemically induced*
D000906:Antibodies; D000925:Anticoagulants; D012701:Serotonin; D010978:Platelet Factor 4; D006493:Heparin