[Hyperthyroidism in TSH-producing hypophyseal adenoma]

For 5 years a 59-year-old man had been treated with thyrostatic drugs for hyperthyroidism of unknown aetiology. As he had been losing weight, computed tomography had been performed in the search for a malignancy. It revealed a hypophyseal space-occupying lesion.

Peripheral thyroid hormone activities were raised, while thyroid-stimulating hormone (TSH) was also raised to 12.4 mU/l and there was evidence of partial hypophyseal insufficiency. Octreotide scintigraphy demonstrated increased activity in the area of the hypophysis.

The transsphenoidal surgery and immunohistochemical tests confirmed the diagnosis of TSH-producing hypophyseal adenoma. The patient became euthyroid after the operation.

TSH-producing hypophyseal adenoma should be considered as a rare cause of hyperthyroidism when it is combined with non-suppressed TSH.