Prolactin is the hormone that stimulates milk production by the breasts.
Prolactinomas generally have very different presentations in women and in men. In addition, women may have a reduction in their sex drive. Most men diagnosed with a prolactinoma have some degree of loss of sex hormone production. The diagnosis of a prolactinoma is confirmed by demonstrating persistently elevated blood levels of prolactin. In all patients with suspected pituitary tumors, a complete pituitary hormone evaluation should be performed.