These are rare tumors, representing approx 2 % of all pituitary adenomas (28). Typically, the presentation is with features of hyperthyroidism, often a mass lesion is present, and these tumors may cosecrete GH or prolactin (29). Most TSH-secreting adenomas produce an excess of the a-subunit, and an elevated molar ratio of a-subunit to intact TSH is present in the serum. Treatment of TSH-secreting tumors is directed at both correction of hyperthyroidism and therapy for the tumor. Antithyroid drugs are usually indicated before surgery. The initial management should be surgical, but data regarding the usefulness of operation are scanty. Success, defined as normalization of thyroid function, has been reported to be approx 40% (30); therefore, postsurgical follow-up is essential. If TSH/a-subunit levels remain elevated, radiation therapy should be considered. Dopamine agonist drugs and somatostatin analogs have also been used, with particularly positive reports after octreotide use (29).
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