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The two most common adenomas that occur in the pituitary are prolactin-secreting and growth hormone-secreting tumors. Prolactin-secreting adenomas are the most common type of tumor and are classified as either microadenomas (less than 1 cm) or macroadenomas (larger than 1 cm) pituitary tumors, adenoma, giantism, prolactinoma, acromegaly. In general, macroadenomas produce more prolactin than smaller tumors, although up to 15 percent of macroadenomas may produce only small amounts of prolactin. Symptoms that occur with prolactin-secreting adenomas include amenorrhea and galactorrhea in women, and decreased libido and erectile dysfunction in men. With rapidly enlarging macroadenomas, visual field defects or headaches 

Growth hormone-secreting adenomas account for about 15 percent of all clinically diagnosed pituitary adenomas.~E Excessive growth hormone in children causes giantism. In adults, overproduction of growth hormone results in acromegaly because the growth plates are closed. Symptoms and physical features of acromegaly include large hands and feet, forehead bossing, fatigue, parotid gland enlargement, decreased libido and erectile dysfunction, paresthesias and nerve entrapment syndromes, and

Treatment. Surgery is the treatment of choice when the tumor is large and the symptoms are significant. Evidence that the tumor is causing local, invasive compression of nearby structures or is in an eccentric location that could compromise carotid sinuses is an indication for surgery. When the tumor is small and the symptoms are minimal and located in a favorable position, medical treatment can

For prolactin-secreting tumors, suppression of prolactin release with dopamine agonists, such as bromocriptine mesylate (Parlodel) and pergolide mesylate (Permax), can reduce galactorrhea. Bromocriptine therapy can be started with a 2.5-mg dose at bedtime and an additional 2.5-mg dose in the morning. The dose may be increased until an acceptable clinical response is 

Bromocriptine side effects include nausea, flushing, headache, hypotension, nasal congestion, and hallucinations. Within six months after starting dopaminergic therapy, about 80 percent of women resume normal ovulation. Clomiphene citrate (Clomid, Serophene) therapy can induce ovulation in women who do not ovulate when receiving bromocriptine. Women wishing to nurse should discontinue bromocriptine.

Dopaminergic agents are also used to suppress growth hormone. Bromocriptine improves acromegaly in 70 percent of patients. Octreotide (Sandostatin), a synthetic version of somatostatin (Zecnil), is effective in 60 to 70 percent of patients with acromegaly and has fewer side effects than bromocriptine.