MON-055 Thyrotropin-secreting Pituitary Adenomas: Case Series

Abstract Disclosure: E. Wang: None. G.E. Vates: None. I. Shafiq: None. Background: Thyrotropin-secreting pituitary adenomas (TSHomas) are rare, accounting for less than 1% of all pituitary adenomas causing hyperthyroidism. Misdiagnosis with primary thyroid disorders often delays accurate diagnosis and management. This study aims to expand diagnostic, prognostic, and therapeutic data on TSHomas to improve care for future patients. Methods: A retrospective analysis was performed in patients with clinical and biochemical diagnosis of TSHomas at the University of Rochester Pituitary Program between 2006 and 2024. Patient’s demographics, laboratory findings, medical history, imaging results and treatment details and treatment were collected and analyzed. Results: Six patients, with an average age of 50.5 years at diagnosis, were identified. Of these, 67% of the patients were female and the mean duration of symptoms before diagnosis was 3.7 years. 67% of patients were previously diagnosed with hypothyroidism and 50% were treated with levothyroxine. The most common presenting symptoms were cardiac abnormalities (83%), including palpitation (50%). Additional symptoms include thermal instability (50%), anxiety (33%) and tremors (33%). Goiter/thyroid nodules was found in 33% of patients. At diagnosis, the average TSH level was 5.8uIU/ml (normal range 0.27-4.20uIU/ml), the average free T4 level was 2.7 ng/dL (normal range 0.9-1.7 ng/dL), and the average free T3 level (measured in three patients) was 8.3pg/ml (normal range 2-4.4 pg/ml). Alpha subunit levels were assessed in four patients and was reported normal in three. All patients were identified to have macroadenoma on MRI, with tumor sizes ranging between 14mm to 27 mm (mean:19mm). Transsphenoidal surgical resection was performed in 83% of patients, and 17% were treated only with somatostatin analogues. One patient was treated with radiation and thyroidectomy after transsphenoidal surgery. Post-treatment TSH levels normalized in 83% of patients. Conclusion: TSHomas are exceedingly rare, with only six cases identified over the past two decades at our Pituitary Program. Misdiagnosis with primary thyroid disorder contributes to significant diagnostic delay. Cardiac abnormalities were the most common symptom at presentation. Despite these challenges, surgical and medical management in a multidisciplinary setting yielded favorable outcomes, with most patients achieving normalization of TSH levels. Presentation: Monday, July 14, 2025