[TSH-рroducing pituitary microadenoma: diagnostic problems in the debut of the disease].

Tumors of the pituitary gland producing thyrotropin hormone (TSH) are rare and account for about 1-3% of all pituitary adenomas, most frequently occurring in persons of young and working age. This article presents a clinical case of thyrotropinoma in a 44-year-old woman, which was diagnosed 6 years after her initial visit to an endocrinologist. At the debut of the disease, thyrotropinoma manifested as an isolated elevation of TSH, with normal levels of free T4 and free T3. The patient was constantly taking β-blockers due to her disturbing tachycardia. She was diagnosed with subclinical hypothyroidism, for which she was periodically observed, controlling her TSH level and taking levothyroxine drugs in a dose of up to 175 mcg, which was accompanied by elevated TSH levels. After 6 years, there was an increase in free T3 and free T4 in addition to TSH. Magnetic resonance imaging with intravenous contrast enhancement revealed a pituitary microadenoma 4 mm in size, and laboratory examination of all tropic hormones revealed an isolated increase in TSH. Transsphenoidal adenomectomy was performed at the diagnosis of TSH-producing pituitary adenoma. During the three-year postoperative follow-up there was no adenoma recurrence, secondary hypothyroidism developed, the patient currently takes levothyroxine 75 mcg per day continuously.