Triiodothyronine antibodies in patients with goiter.

Objective: To investigate the prevalence of triiodothyronine (T3) antibodies in patients with goiter, the influence of these antibodies on the results of thyroid hormone measurements, and the potential relationship between T3 antibodies and thyroid autoantibodies. Methods: We undertook a study of 100 healthy control subjects (80 female and 20 male subjects) who had no clinical or biochemical evidence of thyroid disease and 100 patients (81 female and 19 male patients) with goiter. Serum concentrations of total T3, total thyroxine, free T3, and free thyroxine were measured by radioimmunoassay kits with a coated tube method. An immunoprecipitation method was used to detect anti-triiodothyronine auto-antibodies. Results: Patients with a T3 antibody binding ratio +3 standard deviations (SD) above the mean for the normal control group were considered to have T3 antibodies. Normal control group binding was 2.4 - 1.3%. On the basis of +3 SD, seven patients had T3 antibodies. The mean serum total T3 level was ...