A prolactinoma is a non-cancerous growth (benign tumour) in the pituitary gland that makes a hormone called prolactin.

Tucked away deep inside your brain is a gland called your pituitary gland. It may only be the size of a pea in humans, but it punches way above its weight in terms of its effect on our bodies. One of its main functions is to produce hormones - chemical messengers that are made in one part of the body and travel in the blood to one or more 'target' organs where they have an effect.

One of the hormones the pituitary produces is prolactin. It main job is to stimulate a woman's breast to produce milk after childbirth but prolactin is also made in men. Prolactinomas may cause symptoms as a result of you having too much of the hormone prolactin in your body or because of the tumour pressing on surrounding tissues.

What are prolactinomas?

The pituitary

A prolactinoma occurs when some of the cells in the pituitary gland (the ones producing prolactin) multiply more than usual to form a small growth (tumour) in the pituitary gland. The prolactinoma makes too much prolactin and this can cause symptoms.

Prolactinomas are usually very small. Small prolactinomas (less than 10 mm) are called microprolactinomas. Larger ones (more than 10 mm) are called macroprolactinomas. There is also a rare type called giant prolactinomas, which are more than 4 cm.

For most people the cause is unknown. In rare cases, there may be an inherited (genetic) cause.

How common are prolactinomas?

Prolactinomas are rare but they are the most common type of pituitary gland tumour. It is estimated that about 4 in 10,000 people have a prolactinoma. Prolactinomas occur both in men and in women. Prolactinomas occur most often in women aged 20-50 years, but they can occur at any age.

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Dr Colin Tidy
Peer Reviewer:
Dr John Cox
Document ID:
8710 (v5)
Last Checked:
12 May 2017
Next Review:
29 June 2020

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. Patient Platform Limited has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.