There may be no noticeable signs or symptoms from prolactinoma. However, signs and symptoms can result from excessive prolactin in your blood (hyperprolactinemia) or from pressure on surrounding tissues from a large tumor. Because elevated prolactin can disrupt the reproductive system (hypogonadism), some of the signs and symptoms of prolactinoma are specific to females or males.

In females, prolactinoma can cause:

• Irregular menstrual periods (oligomenorrhea) or no menstrual periods (amenorrhea)
• Milky discharge from the breasts (galactorrhea) when not pregnant or breast-feeding
• Painful intercourse due to vaginal dryness
• Acne and excessive body and facial hair growth (hirsutism)

In males, prolactinoma can cause:

• Erectile dysfunction
• Decreased body and facial hair
• Uncommonly, enlarged breasts (gynecomastia)

In both sexes, prolactinoma can cause:

• Low bone density
• Reduction of other hormone production by the pituitary gland (hypopituitarism) as a result of tumor pressure
• Loss of interest in sexual activity
• Headaches
• Visual disturbances
• Infertility

Women tend to notice signs and symptoms earlier than men do, when tumors are smaller in size, probably because they're alerted by missed or irregular menstrual periods. Men tend to notice signs and symptoms later, when tumors are larger and more likely to cause headache or vision problems.

Prolactinoma is one type of tumor that develops in the pituitary gland. The cause of these tumors is unknown.

The pituitary gland is a small bean-shaped gland situated at the base of your brain. Despite its small size, the pituitary gland influences nearly every part of your body. Its hormones help regulate important functions such as growth, metabolism, blood pressure and reproduction.

Other possible causes of prolactin overproduction include medications, other types of pituitary tumors, an underactive thyroid gland, ongoing irritation to the chest, pregnancy and breast-feeding.

Most prolactinomas occur in women between 20 and 34 years old, but can occur in both sexes at any age. The disorder is rare in children.

Complications of prolactinoma may include:

• Vision loss. Left untreated, a prolactinoma may grow large enough to compress your optic nerve.
• Hypopituitarism. With larger prolactinomas, pressure on the normal pituitary gland can cause dysfunction of other hormones controlled by the pituitary, resulting in hypothyroidism, adrenal insufficiency and growth hormone deficiency.
• Bone loss (osteoporosis). Too much prolactin can reduce production of the hormones estrogen and testosterone, resulting in decreased bone density and an increased risk of osteoporosis.
• Pregnancy complications. During a normal pregnancy, the production of estrogen increases. If you are pregnant and have a large prolactinoma, these high levels of estrogen may cause tumor growth and associated signs and symptoms, such as headaches and changes in vision.

If you have prolactinoma and you want to become or are already pregnant, talk to your doctor. Adjustments in your treatment and monitoring may be necessary.