A prolactinoma is a small, benign pituitary tumor that over-produces the hormone prolactin. Because prolactin touches many body systems, the signs can be subtle at first and easy to blame on stress or aging. In women of child-bearing age, periods often lighten or stop altogether. Breast milk may leak even though there is no pregnancy or nursing; some notice a few drops on a bra or during a shower. Fertility drops. Couples can try for months without success, and libido often fades—interest in sex feels like a switch that will not turn on. In men, the first tip-off is usually... Learn more