Prolactin levels may be elevated for any number of reasons. One of the more common cause is the formation of a benign tumor on the pituitary gland. This noncancerous growth, known as a prolactinoma, directly secretes excessive prolactin while decreasing the levels of other sex hormones.
Diseases affecting a portion of the brain called the hypothalamus can also cause hyperprolactinemia. The hypothalamus functions as the link between the nervous system and the pituitary gland. The increase in prolactin levels can often be directly linked to a tumor, trauma, or infection of the hypothalamus.
Other causes may include:
Hypothyroidism (low thyroid hormone levels)
Cirrhosis of the liver
Chronic kidney failure
Antidepressants (Anafranil, Norpramin)
Antipsychotics (Haldol, Zyprexa, Risperdal)
Antihypertensives ( Verelan, Calan, Covera-HS, Isoptin)
Antinauseals (Reglan, Primperan, Lexapram)
Acid H2 blockers (Tagamet, Zantac)
Estrogen