Endocrine Abstracts

Thyrotropin-secreting pituitary adenomas (TSHomas) are rare functioning pituitary adenomas, accounting for less than 1%. They commonly present as macroadenomas with symptoms of hyperthyroidism. Though surgery is the first line therapy, cure is achieved in only 30–40%, with high rate of post-surgical hypopituitarism. We propose somatostatin analogs having a new role in the management. We report a case of 73 years-old man with a 6-month history of palpitations and progressive dysnea due to an atrial fibrillation. Personal history of hypertension and colon cancer in remission. No family history of thyroid disease. He denied weight lost, visual symptoms, headache, iodine contrast or amiodarone intake. In hospital his heart rate was 130 beats/minute, blood pressure 140/60 mmHg. He had signs of heart failure and goiter. No visual defects were found nor dysthyroid eye disease. Initial thyroid biochemistry revealed a free thyroxine (FT4) concentration 3.95 ng/dl (0.93–1.70 ng/dl), TSH 5.49 µIU/ml (0.27–4.2 µIU/ml) and free triiodothyronine (FT3) 6.3 pg/ml (1.8–4.3 pg/ml), thyroid receptor antibody (TRAb): <0.6 IU/l (negative; <1 IU/l). Alpha subunit 8.1 IU/l (reference range <0.7 IU/l), alpha subunit/TSH molar ratio: 20, sex hormone binding globulin (SHBG) 186 nmol/l (10–57 nmol/), prolactin 17 ng/ml (4–15.2 ng/ml); other pituitary hormones were within the normal reference range. Thyroid ultrasound revealed a goiter with millimetric cystic nodules. The TRH test after 200 mg of TRH iv showed a blunted response: TSH 4.30 at 0 minutes; 4.20 at 20 minutes; 4.10 at 40 minutes; 4.10 at 60 minutes. The pituitary MRI revealed a sellar lesion of 13 mm, with suprasellar extension but without cavernous sinus invasion. Thus, a thyrotropin-secreting pituitary adenoma was suspected but the patient refused surgery and radiotherapy. We started octeotride LAR 20 mg i.m. treatment every 28 days. After six months FT4 decreased to 1.49 ng/dl, TSH to 0.55 µIU/ml and FT3 to 2.42 pg/ml all of them within the normal range. The MRI showed a 7 mm sellar lesion. After 2 years, the patient is in good clinical condition, with no hospital admissions, thyroid hormones are within the normal range and the sellar lesion is stable.

Conclusion: This case supports the increasing evidence of somatostatin analogs as primary therapy in the management of some thyrotropin-secreting pituitary adenomas achieving excellent biochemical and radiologic response.