The Analysis of the Value of the Thyroid Autoantibody Measured by Radioimmunoassay

방사면역측정법에 의한 갑상선 자가항체 측정의 기본적 및 임상적 검토

To evaluate the values of the thyroid autoantibody measured by radioimmunoassay (RIA) and compare it with hemagglutination method (HA) in the normal and the thyroid disease, data were obtained from total 618 persons; 236 healthy persons, 217 patients with Graves' disease (including 113 patients with undertreated Graves' disease), 100 Hashimoto's disease, 31 thyroid nodule, and 34 simple goiter. RSR kit made in England was used and could be detected to at least 3 U/ml. The positive rates of normal group were antimicrosomal antibody (AMA) 31.8%, antithyroglobulin antibody (ATA) 44.5% by RIA and there was no considerable change in sex and age distribution. In Graves' disease, the positive rates of AMA and ATA were 90.4, 76.9% by RIA, 85, 39% by HA. In Hashimoto's disease, 94,91 % by RIA, and 87,48% by HA, respectively. The autoantibody titer by RIA in thyroid autoimmune disease as well as in normal group was more senisitive than that by HA, especially in ATA. There were linear relationships between the titer of RIA and that of HA in AMA of Graves' disease and AMA and ATA of Hashimoto's disease. There was no relationship among thyroid autoantibody, free $T_4$ index, TBII, and TSH. The titers of AMA and ATA were found to decrease in patients with Graves' disease during the course of antithyroid drug therapy. Of the 236 normal subjects, thirty-seven (15.7%) had concentrations of above 7.5 U/ml in AMA, forty. four (18.6%) above 9 U/ml in ATA. These values were considered as the upper limit for the normal range. In Graves' disease, 82.7, 53.8% were above 7.5, 9 U/ml, respectively; In Hashimoto's disease, 82, 79% were positive. We conclude that RIA was more sensitve than HA in measuring the thyoird autoantibody, but we will study further more for determining the normal range and its interpretation.