Description
Prolactin is a hormone released by the pituitary gland. Prolactin is best known for stimulating breast development and enabling milk production in women. In non-pregnant women and in men, abnormally high levels of prolactin may indicate a tumor in the pituitary gland or a pituitary disorder. Prolactin (PRL) is one of the hormones secreted by the anterior pituitary. It is regulated by the hypothalamus via the inhibitory actions of dopamine. It is PRL excess (hyperprolactinemia) that is typically associated with clinical pathology, and both males and females (most commonly) can present with symptoms including menstrual irregularity, sexual dysfunction, and infertility. Prolactin-secreting pituitary tumors known as prolactinomas are often the cause, however any process which interferes with the release of dopamine (prolactin inhibitor) can also be related to hyperprolactinemia.
The excess of PRL inhibits gonadotropin-releasing hormone (GnRH) secretion by the hypothalamus resulting in decreased pituitary production of luteinizing hormone (LH) and follicular stimulating hormone (FSH). During pregnancy and postpartum lactation, serum prolactin increase 10- to 20-fold. Exercise, stress, and sleep also cause transient increases in prolactin levels. Consistently elevated serum prolactin levels (30 ng/mL), in the absence of pregnancy and postpartum lactation, are indicative of hyperprolactinemia. Hypersecretion of prolactin can be caused by pituitary adenomas, hypothalamic disease, breast or chest wall stimulation, renal failure or hypothyroidism. Drugs, including many antidepressants, can elevate prolactin levels. Hyperprolactinemia often results in galactorrhea, amenorrhea, and infertility in females, and in impotence and hypogonadism in males. Renal failure, hypothyroidism, and prolactin-secreting pituitary adenomas are also common causes of abnormally elevated prolactin levels.
