Key Points

• Pituitary disease may manifest with pituitary hormone excess or deficiency or symptoms of mass expansion, including headaches and visual disturbances.

• Pituitary adenoma is the most common cause of pituitary dysfunction in adults.

• Hypothalamic-pituitary axis function should be assessed in patients with a mass in the sella turcica.

• Evaluation of pituitary dysfunction involves serum measurements (prolactin, GH, IGF-1, FT4 TSH), free cortisol or dexamethasone suppression test, and imaging.

The most common cause of pituitary disease is the development of benign tumors. Adenomas can cause symptoms because of excessive production of hormones such as pro-lactin, GH, or adrenocorticotropic hormone (ACTH), or can cause pituitary hormone insufficiency secondary to tissue destruction. The pituitary hormones that can be lost early during the gradual destruction of pituitary tissue include GH and GnRH, followed by TSH and lastly ACTH. Occasionally, however, the autoimmune destruction of the pituitary can be cell specific and cause selective pituitary hormone deficiency.

Pituitary tumors can expand into the optic chiasm and hypothalamus and cause visual field defects and symptoms of hypothalamic disease, respectively. The classic symptom of optic chiasm compression is bitemporal hemianopsia (inability to see either side). Early manifestations of optic chiasm impingement can be subtle and include seeing images that float apart or seeing one half of the face higher than the other half (Picasso effect, or hemifield slide phenomenon). These symptoms emerge when the patient is tired or anxious and are the result of failure to fuse the images from both eyes because of the lack of nasal fields. Expansion of tumors into the hypothalamus can cause disturbances in sleep, appetite, temperature regulation, sweating, water balance, and memory (Mooradian and Morley, 1988).

In children, pituitary adenomas are less common, and hypothalamic pituitary dysfunction is typically the result of hypothalamic tumors, notably craniopharyngiomas.

When microadenoma (<10 mm) is discovered incidentally, the initial evaluation should seek hormone hypersecretion by measuring levels of serum prolactin, insulin-like growth factor type 1 (IGF-1), TSH, and free thyroxine (FT4) levels and 24-hour urine free cortisol or a 1-mg overnight dexamethasone suppression test (Mooradian and Koren-man, 2007). More extensive workup is required for pituitary masses larger than 10 mm (macroadenoma), regardless of symptoms. Overall workup and management of pituitary disease should include identifying and treating hormonal deficiency and excess as well as diagnosing and managing mass effects of the tumors.

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