[Changes in antimicrosomal antibody, serum thyroglobulin and thyrotropin binding inhibitor immunoglobulin in a patient with silent thyroiditis who experienced four thyrotoxic episodes].

Serial changes of thyroid hormones, TSH, anti-thyroidal antibodies, serum Tg and TBII were studied in a patient with silent thyroiditis who experienced four episodes of transient thyrotoxicosis in a follow-up period of five years. The titers of MCHA were high in the thyrotoxic episodes and further increased in the following hypothyroid phases. In the euthyroid phase it became lower. The serum level of Tg was normal or moderated elevated in the thyrotoxic episodes, and it further elevated in the hypothyroid phase. Surgical biopsy, performed in the euthyroid phase about one year after the forth thyrotoxic episode, revealed the findings of Hashimoto's disease. Two different types of transient thyrotoxic episode, one with positive TBII and high uptake and the other with negative TBII and low uptake, were observed in the same patient with silent thyroiditis. In the beginning of the clinical course, the patient showed positive TBII, high 131I-uptake (77%) in the second episode of thyrotoxicosis, no response of TSH to TRH administration and absence of T3-suppressibility. The value of TBII gradually became normal and was negative at the forth episode of thyrotoxicosis when 131I-uptake was low (1.3%). After this last episode, TSH response to TRH administration was normal in euthyroid phase and augmented in hypothyroid phase. The presence of transient positive TBII and of histological changes of Hashimoto's disease was suggestive of the close relationship between Graves' and Hashimoto's diseases.