A Case of Thyrotropin-Secreting Pituitary Adenoma (TSH-oma)

Thyrotropin-secreting pituitary adenomas (TSHomas) are rare tumors and represent about 1-2% of all pituitary adenomas (prevalence is about one case per million) and cause secondary or central hyperthyroidism. The number of reported cases of TSH-omas tripled in the last decade. The increased number of reported cases resulted principally from the introduction of ultrasensitive immunometric assay for TSH as a first-line test for the evaluation of thyroid function (1). TSH-secreting adenomas are part of the syndrome of inappropriate secretion of TSH (SITSH). The hormonal profile is characterized by nonsuppressed TSH in the presence of high levels of free thyroid hormones (FT3 and FT4). Normal or elevated thyrotropin levels in hyperthyroid patients are characteristic findings of TSH-secreting