Improved laboratory confirmation of heparin-induced thrombocytopenia type II. Time course of antibodies and combination of antigen and biologic assays.
We studied whether laboratory confirmation of heparin-induced thrombocytopenia (HIT) can be improved after antigen clearance by determining free antibody and combining the results of an antigenic and a biologic assay. Blood samples taken over 40 days in 14 patients with HIT with thromboembolism underwent fluorescence-linked immunofiltration and the carbon 14-serotonin release assays. Of the 14 patients, 11 showed positive results in both assays at day 1 after stopping heparin. The 3 patients with negative results seroconverted in one or both assays during the subsequent 7 days. Combining the positive results of the assays increased the sensitivity from 85% at day 1 to 100% at day 7. Assay results became negative in all patients within 40 days. The platelet count normalized between days 2 and 9 after withdrawal of heparin. It is assumed that the free antibody can be detected after withdrawal of heparin and after clearance of the platelet factor 4-heparin complex in patients with HIT.
Harenberg
J
J
Department of Medicine I, University Hospital, Theodor-Kutzer-Ufer, D-68167 Mannheim, Germany.
Wang
L
L
Hoffmann
U
U
Huhle
G
G
Feuring
M
M
D000368:Aged; D000941:Antigens / Q000097:blood*; D001323:Autoantibodies / Q000097:blood*; D002250:Carbon Radioisotopes; D005260:Female; D005456:Fluorescent Dyes; D006493:Heparin / Q000009:adverse effects* / Q000097:blood / Q000276:immunology; D006801:Humans; D007105:Immune Complex Diseases / Q000139:chemically induced / Q000276:immunology; D007118:Immunoassay; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D010976:Platelet Count; D010978:Platelet Factor 4 / Q000276:immunology* / Q000378:metabolism; D012680:Sensitivity and Specificity; D012701:Serotonin / Q000097:blood; D013921:Thrombocytopenia / Q000139:chemically induced / Q000175:diagnosis* / Q000276:immunology*
D000941:Antigens; D001323:Autoantibodies; D002250:Carbon Radioisotopes; D005456:Fluorescent Dyes; D012701:Serotonin; D010978:Platelet Factor 4; D006493:Heparin