A CASE OF HYPERTHYROIDISM DUE TO PITUITARY RESISTANCE TO THYROID-HORMONE

A fifteen-year-old male was admitted to our hospital because his thyro id function showed a lack of TSH suppression in the face of elevated t hyroid hormone. This patient complained of heat intolerance, palpitati on and hand tremor. Peripheral indices of thyroid hormone action indic ated a hypermetabolic state. Serum TSH did not respond sufficiently to TRH stimulation, suggesting TSH-secreting pituitary adenoma. However, sellar CT scan and MRI images did not demonstrate any pituitary adeno ma. Moreover, the serum TSH a-subunit concentration was not high and s erum TSH was partially suppressed by the administration of T-3. Furthe rmore, the results of single stranded conformation polymorphism (SSCP) suggested the existence of mutation(s) in the exon 7 of T-3 receptor beta (TR beta) gene of this patient. These findings support the diagno sis of pituitary resistance to thyroid hormone.