Endocrine Abstracts

Introduction: Thyrotropinomas are usually considered when the TSH level is inappropriately elevated or normal in a hyperthyroid patient with increased serum T₄ levels, regardless of the presence of visible tumor on imaging. The prevalence of these adenomas, which account for 0.5–3% of all pituitary tumors has been estimated to be around one case per million. Most thyrotroph adenomas are large and invasive at diagnosis, and present with signs and symptoms of an expanding mass, including temporal visual field defects. Here, we report a patient treated with somatostatin analogue with pituitary macroadenoma and hyperthyroidism.

Case reports: A 64-year-old female patient, who had undergone surgical procedure in 2014 for solitary fibrous tumor in the left parietal region, applied to be checked because of enlarged hypophysis gland documented via cranial MRI performed during follow-up visits. Laboratory findings revealed high levels of fT₃ (8.56 pg/ml) and fT₄ (2.1 ng/ml) with TSH (6.32 UI/ml) higher than its normal limit. On the MRI of the hypophysis, a 22×18×14 mm lesion consistent with macroadenoma, which was heterogeneously contrasted after IV Gad injection, was detected in the mid-left half of the pituitary gland. The lesion exceeds the lateral inter-carotid line in the left aspect and surrounds the left ICA higher than 240 degree. Other hormones of the anterior hypophysis were within the normal range. SHBG was 153.9 (30–100 nmol/l) and alpha subunit was 3.9 (0–1.6 IU/l), which were high. There was no response to TRH stimulation test. Methimazole was commenced at a dose of 20 mg and transnasal transsphenoidal pituitary adenomectomy was performed. Somatostatin analogue (Octreotid LAR 10 mg/28 day) therapy was started for the patient, who had residual adenoma (20×15 mm) and in whom euthyroidism could not be achieved. Methimazole was interrupted in the 9th month of somatostatin analogue treatment and determining that the size of adenoma is 10×9×8 mm.

Conclusion: Most thyrotrophs express variable number of somatostatin receptors (SSTR), particularly SSTR2 and SSTR5. Somatostatin analogues could be considered in the treatment of persistent disease following the surgical procedure performed for TSH-secreting adenomas.