Endocrine Abstracts

Introduction: Thyrotropin-secreting pituitary adenomas (TSHomas) are a rare cause of hyperthyroidism and represent <1% of all pituitary adenomas. The majority of TSHomas (70%) secrete TSH alone, while mixed adenomas are not infrequent.

Design: Herein, we reported the findings of six patients with TSHoma (mean age 44 yr, 4 female, 2 male). Mean TSH value was 15.1 mIU/L (3.3–38.0) who were followed-up in our department.

Results: Symptoms of hyperthyroidism were the initial findings in all these patients. Three of them recieved high dose antithyroid drugs for hyperthyroidism, Because of unresponsiveness, radioactive iodine (n=1) or thyroidectomy (n=2) was performed as a definitive treatment for hyperthyroidism before the correct diagnosis of TSHoma. The diagnosis delayed for 3–11 years. Four of the patients secrete TSH alone, while three of them were mixed adenomas [TSH, growth hormone (GH) (n=1); TSH, GH and prolactin (n=1); TSH, prolactin (n=1)].

Five of the cases had macroadenoma invading sphenoid and/or cavernous sinuses, and two of them also showed compression on optic tractus, one patient had microadenoma. The primary therapeutic approach was transsphenoidal surgery. İmmunohistochemically, GH, prolactin and TSH positivity was evident in two patients and one also showed diffuse Pit1 positivity. One patient showed positivity, for TSH and prolactin and another showed focal immunostaining for GH and FSH.

No remission was noted in four patients and medical therapy with somatostatin analogues (SSAs) and thereafter cabergoline were started. Radiotherapy was performed for one patient postoperatively. Hormonal control was achieved in all treated patients.

Conclusion: The delayed diagnosis of TSHoma usually cause inappropriate treatment of hyperthyroidism. Transsphenoidal surgery should be the first line treatment. If remission is not achieved medical therapy with SSAs and cabergoline and also radiotherapy should be options.