A prolactinoma is a benign tumor of the pituitary gland that produces a hormone called prolactin. It is the most common type of pituitary tumor.
Prolactin stimulates the breast to produce milk during pregnancy.
After delivery of the baby, a mother's prolactin levels fall unless she breast feeds her infant. Each time the baby nurses, prolactin levels rise to maintain milk production. The pituitary gland, sometimes called the master gland, plays a critical role in regulating growth and development, metabolism and reproduction. It produces prolactin and a variety of other key hormones. The pituitary gland sits in the middle of the head in a bony box called the sella turcica .