[TSH receptor antibodies determined by the Thybia test in children with hyperthyroidism]

Using a radioreceptor assay Thybia-test, we studied 22 girls with Graves' disease, aged 4.0 to 20.4 years (mean = 13.8 years). Sera of 9 girls were obtained before therapy, 20 during treatment with methimazole, 4 in remission and 2 relapse. The total number of tested sera was 113. Control sera were obtained from 19 age-matched controls. The results of Thybia-test were positive in 7 of 9 girls with Graves' disease before treatment (77.8%) and in both girls in relapse. Of 89 samples of sera taken during drug therapy Thybia-test was positive in 51. Only 3 of 13 sera taken in remission gave positive results. The highest mean values of Thybia-test were detected in patients in relapse (46.2%), and in patients before therapy (23.9%). During treatment mean values became lower (14.4%) and were the lowest in remission of the disease (6.9%). The results of Thybia-test in controls ranged from 0% to 7.5% (mean = 1.93 +/- 2.78%). Significant differences were noticed between mean values of Thybia-test of patients before therapy and controls as well as between patients during therapy and controls. Six girls were studied after discontinuation of thyreosuppressive therapy. In 5 results of Thybia-test were negative. Three of them are still in long remission. Two were in short remission and relaps in both of them was followed by convertion of Thybia-test to positive. At the end of treatment the only patient with positive Thybia-test was in remission and Thybia-test was-later converted to negative. Our study shows that Thybia-test is a valuable method in addition to others used to correlate the natural history of the disease with the results of therapy. We are still unable to make a definite statement on the significance of this method in prediction of relapse and remission of Graves' disease.