[Determination of TSH receptor antibodies--clinical value].

In 223 patients suffering from Graves' disease, TSH receptor autoantibodies in serum were measured using the commercially available TRAK assay (Henning, Berlin). Of 53 patients examined before treatment, 50 (94%) were TRAK-positive. During drug therapy the number of positive titers decreased. Of 38 patients examined after a therapy course for the first time, only two (5.3%) were positive. Evaluation of antibody status after all three forms of treatment (drugs, surgery, radioiodine) in 146 patients showed that of 33 patients with persistently positive titers only nine relapsed. Of the 24 patients out of this group without relapse, 15 had operative or radioiodine treatment. The 113 patients becoming or remaining TRAK-negative after treatment showed 12 relapses, in all these cases relapse was accompanied or announced by conversion to positive TRAK values. The high sensitivity and specificity of the assay (in a control group of 40 patients with autonomous adenoma no positive TRAK was seen) allow to use the test for discrimination between Graves' disease and disseminated autonomy of the thyroid in patients presenting with diffuse hyperthyroidism. Thus, by helping to establish an exact diagnosis, TRAK could become important for therapy planning. Concerning relapse prediction, our data are less promising since only 39% of patients with persistently positive TRAK titers relapsed. TRAK is not a reliable indicator of relapse risk especially in patients operated or treated with radioiodine. On the other hand, 10% of patients showing negative titers after treatment also relapsed, all turning to positive TRAK values at the same time.