Prolactinomas are the most common hormone-secreting pituitary tumors. It is a noncancerous (benign) pituitary tumor that produces a hormone called prolactin. This results in too much prolactin in the blood. These occur most commonly in people under age 40. They are about five times more common in women than in men, but are rare in children. Larger tumors are more common in men. They tend to occur at an older age. The tumor can grow to a large size before symptoms appear.
Symptoms: When prolactin levels get increased there will be no periods, milk production will occur (infrequent in men), loss of axillary and pubic hair and Small gonads, gynecomastia, erectile dysfunction (in males). When there is mass effect then, bitemporal hemianopsia (due to pressure on optic chiasm), vertigo, nausea, vomiting are the symptoms.
Causes: A prolactinoma occurs when some of the cells in the pituitary gland (the ones producing prolactin) multiply more than usual. We do not know what makes the cells multiply in the first place. In rare cases, there may be an inherited (genetic) cause.