ABSTRACT
BACKGROUND/AIMS: Thyrotropin (TSH)-secreting pituitary adenoma (TSHoma) is rare and represents 1~2% of all pituitary adenomas. TSHoma should be distinguished from the thyroid hormone resistance syndrome. Patients with TSHoma may be misdiagnosed with primary hyperthyroidism and often receive inappropriate thyroid gland treatment. METHODS: We assessed the clinical characteristics of patients with TSHoma who presented to Severance Hospital at the Yonsei University College of Medicine, Seoul, Korea between 2005 and 2009. RESULTS: Of 484 patients who underwent pituitary tumor resection, eight (1.65%; five women and three men) were found to have TSHoma. The mean age was 40.6+/-8.9 years at diagnosis (range, 28~55 years). The median duration from onset of symptoms to diagnosis was 17 months (range, 4~60 months). Four patients had overt symptoms of hyperthyroidism and two had visual field defect. Six patients had elevated free thyroxine (FT4) levels with elevated or inappropriately normal TSH levels, and two patients had symptoms associated with Hashimoto's thyroiditis. The serum levels of free alpha-subunit measured in two patients were elevated. Six of the tumors were macroadenomas (>10 mm) and two were microadenomas. Complete tumor removal was achieved in all patients. Five patients had preoperative anterior pituitary dysfunction; three patients recovered from this after surgery. Three patients were lost to follow up and five patients showed no evidence of recurrence or hyperthyroidism in the follow-up period (mean, 30.8 months, range, 3~57). CONCLUSIONS: Early diagnosis and complete removal of the tumor mass may improve the neurological and endocrine deficits.