A case of pituitary resistance to thyroid hormone with nonfunctioning pituitary microadenoma / 대한내과학회지

ABSTRACT

Resistance to thyroid hormone (RTH) is an autosomal dominant disorder that's characterized by inappropriate normal or elevated TSH levels despite of the elevated thyroid hormone levels. RTH is distinguished from the TSH secreting pituitary adenoma by performing the TRH stimulation test, TSH alpha subunit measurement and sellar MRI. A 23 year old woman visited our hospital complaining of fatigue, palpitation and heat intolerance and she had an anterior neck mass. She had elevated total T3, free T4 and TSH levels. The serum TSH levels were increased during the TRH stimulation test before and after T3 suppression. The serum TSH alpha subunit showed a normal response and the serum TSH alpha subunit/TSH molar ratio did not increase over 1.0 with TRH stimulation. Thyroid hormone receptor beta gene mutation was identified. Although a left pituitary microadenoma was revealed on sellar MRI, the patient was diagnosed as having pituitary RTH with a nonfunctioning pituitary microadenoma. We report here on a patient with pituitary RTH and a nonfunctioning pituitary microadenoma, and this is the first such case in Korea.