A pituitary tumour causing excess secretion of prolactin, a hormone that influences fertility and breast milk production
A prolactinoma is a noncancerous type of pituitary tumour. The tumour causes an excess of the hormone prolactin, which is essential for breast development and milk production in women. Although women’s prolactin levels normally increase during pregnancy, an excessive level of the hormone can have adverse effects in both men and women. Prolactinomas occur more frequently in women. The cause is unknown.
A prolactinoma usually develops over a period of several years, and the symptoms appear gradually. Symptoms that affect only women include:
Irregular or absent menstrual periods (see Amenorrhoea).
Some symptoms of prolactinoma affect only men, and these include:
There are some symptoms that affect both sexes, and these include:
Leakage of fluid from the nipples.
Reduced interest in sex.
An untreated tumour may grow large enough to put pressure on surrounding areas of the brain. The pressure may cause headaches, loss of the normal field of vision (see Visual field defects), or hypopituitarism.
If your doctor suspects that you have a prolactinoma, he or she will initially want to know if you could be pregnant or taking drugs, such as certain antipsychotics, that raise levels of prolactin and are not related to the presence of a prolactinoma. You will probably have a blood test to measure hormone levels. If the prolactin level is high, you may have imaging tests such as CT scanning or MRI to look for a pituitary tumour. If a tumour is found, drugs may be given to reduce production of prolactin (see Pituitary drugs). If treatment with drugs is unsuccessful, surgery or radiotherapy may be necessary to remove or destroy the tumour.
Drug treatment is successful in more than 3 in 4 cases. In the others, surgery or radiotherapy is usually effective. Less commonly, the tumour may recur and treatment may need to be repeated.
If a woman becomes pregnant after treatment for a prolactinoma, she will be monitored carefully because the tumour may recur as a result of the hormonal changes. Drugs to lower prolactin levels are discontinued during pregnancy.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.