M, a 16-year-old student was shocked when she found a small amount of whitish discharge oozing out from her nipples when she accidentally pressed on them while bathing. Upset and disturbed, she went and told her mother who brought her to see me the next day.
M had her first menstruation at the age of 12. Since then, it had been irregular, occurring every two to three months. For the past six months, she had had no “proper” menses except for some spotting on and off. She did not pay much attention and did not inform her mother.
Physical examination revealed a small amount of milky discharge from her nipples on squeezing. Gynaecological examination did not show any abnormalities. Examination of the eyes was normal.
The blood prolactin (milk hormone) level was elevated about two times that of the normal. MRI of the pituitary gland showed a small tumor about 3mm in size.
M was suffering from a prolactin-secreting tumor of the pituitary gland called prolactinoma. The pituitary gland is a pea-sized hormone-secreting organ attached to the base of the brain. It controls the growth, the development and the functioning of other hormone-secreting glands in our body including the ovaries.
Prolactinoma is noncancerous. Based on the size of the tumors, those that are less than 10mm are known as microprolactinoma and those beyond 10mm, macroprolactinoma. The tumor causes the pituitary gland to produce excessive prolactin which stimulates breast milk production and suppresses ovulation.
How common is prolactinoma?
Prolactinoma is the most common benign hormone-producing tumor of the pituitary gland, making up to 40% of the total number. Studies have estimated that it occurs in about 3 per 10,000 women and is most often seen in the age group 25 to 34 years.
Cause of prolactinoma
The exact cause of prolactinoma is poorly understood.
Symptoms and signs of prolactinoma
Prolactinoma may not cause any noticeable signs or symptoms when small. However, excessive prolactin in the blood may result in the following symptoms:
- Irregular menstrual periods or no menstrual periods
- Milky discharge from the breasts when not pregnant or breast-feeding
- Painful intercourse due to vaginal dryness
- Loss of interest in sexual activity
- When the tumor gets larger, it may press on the surrounding structures in the brain, resulting in symptoms that include:
- Vision changes-visual field deficits, blurred vision, decreased visual acuity
Diagnosis and Management of prolactinoma
Diagnosis of prolactinoma is by the elevated blood levels of prolactin and is confirmed by the MRI image of the pituitary gland. Treatment is by using oral medications such as dopamine agonists. Cabergoline and bromocriptine are the two commonly used drugs.
M was put on bromocriptine. She tolerated the medication well. The milk secretion stopped after a month and her menstruation returned to normal after about 3 months of medication. She had been on the medication since and was being monitored periodically for her blood prolactin levels which had remained normal since.