Prolactin

During pregnancy and postpartum lactation, serum prolactin can increase 10- to 20-fold. Exercise, stress, and sleep also cause transient increases in prolactin levels. Consistently elevated serum prolactin levels (>30 ng/mL) indicate hyperprolactinemia in the absence of pregnancy and postpartum lactation. Pituitary adenomas, hypothalamic disease, breast or chest wall stimulation, renal failure, or hypothyroidism can cause prolactin hypersecretion. Some drugs, including many antidepressants, are also common causes of abnormally elevated prolactin levels. Hyperprolactinemia often results in galactorrhea, amenorrhea, infertility in females, and impotence and hypogonadism in males. Renal failure, hypothyroidism, and prolactin-secreting pituitary adenomas are common causes of abnormally elevated prolactin levels.