Importance  Pituitary adenomas may hypersecrete hormones or cause mass effects. Therefore, early diagnosis and treatment are important.

Observations  Prevalence of pituitary adenomas ranges from 1 in 865 adults to 1 in 2688 adults. Approximately 50% are microadenomas (<10 mm); the remainder are macroadenomas (≥10 mm).

Mass effects cause headache, hypopituitarism, and visual field defects. Treatments include transsphenoidal surgery, medical therapies, and radiotherapy. Prolactinomas account for 32% to 66% of adenomas and present with amenorrhea, loss of libido, galactorrhea, and infertility in women and loss of libido, erectile dysfunction, and infertility in men; they are generally treated with the dopamine agonists cabergoline and bromocriptine.

Growth hormone–secreting tumors account for 8% to 16% of tumors and usually present with enlargement of the lips, tongue, nose, hands, and feet and are diagnosed by elevated insulin-like growth factor 1 levels and growth hormone levels; initial treatment is surgical. Medical therapy with somatostatin analogues, cabergoline, and pegvisomant is often also needed.

Adrenocorticotropic hormone (ACTH)–secreting tumors account for 2% to 6% of adenomas and are associated with obesity, hypertension, diabetes, and other morbidity. Measurement of a late-night salivary cortisol level is the best screening test but petrosal sinus sampling for ACTH may be necessary to distinguish a pituitary from an ectopic source.

The primary treatment of Cushing disease (hypercortisolism due to ACTH-producing adenomas, which is the cause in approximately 65% of the cases of hypercortisolism) is adenoma resection and medical therapies including ketoconazole, mifepristone, and pasireotide.

Hyperthyroidism due to thyroid-stimulating hormone–secreting tumors accounts for 1% of tumors and is treated with surgery and somatostatin analogues if not surgically cured. Clinically nonfunctioning adenomas account for 15% to 54% of adenomas and present with mass effects; surgery is generally required, although incidentally found tumors can be followed if they are asymptomatic.

Conclusions and Relevance  Patients with pituitary adenomas should be identified at an early stage so that effective treatment can be implemented. For prolactinomas, initial therapy is generally dopamine agonists. For all other pituitary adenomas, initial therapy is generally transsphenoidal surgery with medical therapy being reserved for those not cured by surgery.

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