Significant fluctuation of thyroid function in children with chronic lymphocytic thyroiditis.

In order to investigate the degree of pituitary reserve of TSH secretion and the fluctuation of thyroid function in children with chronic lymphocytic thyroiditis, TSH response to TRH was examined in 42 patients, and the thyroid function was carefully followed up in two patients retrospectively and in four prospectively. Increased basal TSH levels were revealed in seven patients (16.8%), and an exaggerated response of TSH to TRH loading in 15 (35.8%). We retrospectively observed spontaneous recovery of thyroid function in two cases. In one of them, two episodes of a transient decrease in thyroid function over a period of several years were noted. Prospectively, low normal T4, elevated TSH and normal T3 were detected in two cases at the first visit. Thereafter, TSH levels decreased to the normal range and the exaggerated response of TSH to TRH became normal. In two other cases, typical transient hypothyroidism occurred during the observation period. These fluctuations lasted for only a few months, and concomitant changes in the size of the thyroid gland were observed. No signs or symptoms suggesting viral infection were noted during the study period. Nor were changes in titers of thyroid auto-antibodies detected. These results show that the secretion of TSH is exaggerated and the thyroid function is decreased in adolescents with chronic lymphocytic thyroiditis, but the thyroid function may fluctuate from euthyroid to hypothyroid within a short period. The causes of these changes, especially of the transient hypothyroidism remain to be classified.