Diagnosis and treatment of TSH-secreting adenomas: review of a longtime experience in a reference center

TSH-secreting pituitary adenomas are among the less prevalent pituitary tumors, corresponding to 0.9–1.5% of all pituitary adenomas in surgical series.

A series of 11 patients with TSH-secreting and cosecreting adenomas diagnosed and treated in the last 25 years in a single center is described.

The mean age at diagnosis was 37 years (range 18–80 years; median 23 years); the ratio of male-to-female patients was similar (6M:5F). Only three patients was the correct diagnosis established shortly after the initial medical evaluation. Other four patients were initially diagnosed with other pituitary adenomas (prolactinoma, acromegaly, and non-secreting pituitary tumor) and another four diagnosed with primary hyperthyroidism. There was a mean diagnostic delay of 6.0 years (range 0.5–25 years; median 2 years). Nine patients had macroadenomas and two patients had microadenomas. Seven patients underwent pituitary surgery which controlled the disease in only two (one micro- and one noninvasive macroadenoma). The other treatments were directed to the thyroid gland (surgery or ¹³¹I radiotherapy), pituitary radiotherapy, and somatostatin analog.

In spite of its relatively straightforward diagnosis, which includes clinical/subclinical hyperthyroidism with or without goiter, increased free thyroxine and nonsuppressed TSH levels, and pituitary mass, the diagnosis of TSH-secreting and cosecreting adenomas was frequently unrecognized and thus much delayed. Serum alpha-subunit levels were high in nearly all patients with TSH-secreting adenomas and useful in excluding other conditions in the differential diagnosis. Proper indication and interpretation of simple laboratory tests should be emphasized in medical education to improve diagnostic accuracy.