Nonsecreting pituitary tumors.

Nonfunctioning pituitary adenomas represent approximately 25 per cent of all clinically apparent pituitary tumors. The tumors are usually macroadenomas and present with symptoms caused by mass effect or hypopituitarism. In addition to structural studies and assessment of pituitary hormone function, all patients with clinically nonfunctioning tumors should have an alpha-subunit determination. High normal or elevated gonadotropins in this setting are suspicious for an underlying gonadotroph adenoma. Alpha subunit, LH-beta, and FSH-beta can be measured in the serum of some patients with nonfunctioning adenomas. Other groups of patients may have tumors in which defects in hormone biosynthesis or processing prevent detectable hormone hypersecretion, or no hormones are produced. The majority of nonfunctioning adenomas have evidence of gonadotropin or glycoprotein hormone subunit production when studied in vitro. An additional tumor group has evidence of ACTH production without biochemical hypercortisolism. Transsphenoidal decompression is the treatment of choice for patients with nonfunctioning adenomas. Pituitary function may improve following surgery in a subset of patients. Postoperative conventional radiotherapy is recommended when there is evidence of residual tumor and/or extensive extrasellar extension preoperatively.