H. Urbano Ferreira*a (Dr)

a Centro Hospitalar Universitário São João, Porto, PORTUGAL

* maria.helena.ferreira@gmail.com

Introduction: Thyrotropin (TSH)-secreting adenomas are rare tumours of the pituitary and a rare cause of hyperthyroidism, accounting for less than 1% of the cases of both. Surgery is the first-line treatment, although it is frequently unsuccessful.

Case report: A 63-year-old woman was sent to Endocrinology consultation for multinodular goiter and elevation of free T4 (FT4 1.74 [0.70-1.48]ng/dL) and free T3 levels (FT3 6.53 [1.71-3.71] pg/mL) with normal TSH (4.09 [0.35-4.94] µUI/mL). She had a 6-month history of general malaise, weight loss and tiredness. She had elevated levels of ferritin (322.4 [14-233] ng/mL) and steroid hormone binding globulin (>200 [14.1-68.9] nmol/L). She did a TRH test, which did not result in a significant elevation of TSH nor of the α-subunit. Octreotide test resulted in a 57% reduction in the levels of TSH. These findings were consistent with a TSH-secreting pituitary adenoma. Magnetic resonance imaging (MRI) confirmed the presence of an 8 mm adenoma of the pituitary. The patient underwent transsphenoidal resection of the adenoma, which resulted in normalization of thyroid function (TSH 1.51µUI/mL; FT4 1.09 ng/dL; FT3 2.83 pg/mL). However, three months after surgery there was a relapse of the hyperthyroidism with elevated levels of FT4 (2.06 ng/dL) and FT3 (6.09 pg/mL) and an unappropriately normal level of TSH (3.32 µUI/mL), without evidence of tumour recurrence on MRI. She is currently under treatment with octreotide LAR 10 mg/month with normalization of thyroid function.

Conclusion: Although surgery is the definite treatment for TSH-secreting adenomas, cure will only occur in one third of these individuals. Therefore, medical management from the beginning is an alternative. Maintenance of euthyroidism depends on the use of medical therapy, such as somatostatin analogs.

The author has declared no conflict of interest.