Abstract
Blood samples were obtained from 20 patients with Graves' disease at three successive monthly visits to our hospital and serum levels of free thyroxine and TSH were measured. TSH was measured using two different methods in a same specimen. One was radioimmunoassay, TSH (RIA) and the other was high sensitive assay by immunometric methods, TSH (DPC). In four patients still showed the hyperf unction of thyroid gland in spite of medication of antithyroid drugs. The relations between changes in FT 4 levels and TSH (RIA) or TSH (DPC) were investigated to know the benefit of TSH (DPC) in clinical practice of Graves' disease. Simple regression analysis of TSH (RIA) and TSH (DPC) showed a positive correlation. A negative correlation was observed between FT4 and TSH (RIA) or TSH (DPC), respectively. TSH (DPC) showed expected changes following the change in FT4 levels in four patients with hyperthyroid state, although obtained THS levels were very low. TSH (RIA) levels, however, showed unexplainable movements in three of four patients. From these results, the usefulness of TSH (DPC) in Graves' disease was suggested. TSH levels measurd with this method were sensitive even where blood TSH levels were very low, which can lead to the correct therapeutic approach in patients with Graves' disease.
