title: Determination of heparin-platelet factor 4-IgG antibodies improves diagnosis of heparin-induced thrombocytopenia.
abstract: Only a few patients with heparin-induced antibodies develop heparin-induced thrombocytopenia (HIT). In this study, we investigated whether different immunglobulin classes can be used to differentiate between antibody-positive patients with and without HIT. Four different patient populations were investigated: 32 patients with the immune type of HIT with thromboembolic complications, 13 patients with HIT without thromboembolism, 24 patients with heparin-platelet factor 4 (PF4) antibodies without clinical symptoms of HIT, and 20 heparin-treated patients with thrombocytopenia caused by other reasons. In all patients the immunglobulin mixture of IgG, IgM and IgA, and the single immunglobulin classes of heparin-PF4 antibodies, were investigated. No significant differences between HIT patients with thromboembolic complications and patients with isolated HIT were found concerning the different immunglobulin classes. Antibody-positive patients with HIT had significantly higher levels of IgG antibodies than those without HIT (P < 0.05), while they did not differ concerning IgM and IgA antibodies. By determining IgG antibodies, the specificity of the enzyme-linked immunosorbent assay (ELISA) system was increased without loss of sensitivity. Heparin-PF4-IgG antibodies can identify patients at risk of developing life-threatening HIT. Future ELISAs should only include this immunglobulin class, as the determination of the antibody mixture may lead to overestimation of HIT.
authors.affiliation: Medical Department of Internal Medicine, Division of Angiology, University Hospital, Frankfurt, Germany. Lindhoff-Last@em.uni-frankfurt.de
authors.forename: E
authors.initials: E
authors.lastname: Lindhoff-Last
authors.forename: F
authors.initials: F
authors.lastname: Gerdsen
authors.forename: H
authors.initials: H
authors.lastname: Ackermann
authors.forename: R
authors.initials: R
authors.lastname: Bauersachs
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000906:Antibodies / Q000097:blood*; D000936:Antigen-Antibody Complex / Q000032:analysis*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D006493:Heparin / Q000009:adverse effects* / Q000276:immunology; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis*; D008875:Middle Aged; D010978:Platelet Factor 4 / Q000276:immunology*; D012680:Sensitivity and Specificity; D013921:Thrombocytopenia / Q000139:chemically induced* / Q000175:diagnosis
chemical_list: D000906:Antibodies; D000936:Antigen-Antibody Complex; D007074:Immunoglobulin G; D010978:Platelet Factor 4; D006493:Heparin