
A prolactinoma is a benign tumor (called an adenoma) of the pituitary gland. A prolactinoma produces an excessive amount of the hormone prolactin. Prolactin is a natural hormone which supports a woman's normal lactation, which is the secretion of milk by the mammary glands of the breast. Prolactinomas are the most common type of pituitary tumor. Symptoms of prolactinoma are caused by pressure of the tumor on surrounding tissues or by excessive release of prolactin from the tumor into the blood (causing a condition known as hyperprolactinemia).
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