Prolactinoma
A prolactinoma is a non-cancerous (benign) growth in the pituitary gland that produces excess prolactin. The pituitary gland is a small gland at the base of the brain that controls many of the body's hormones. Prolactinomas are the most common type of hormone-producing pituitary tumour.
In women, excess prolactin can cause irregular or absent periods, milky discharge from the breasts (galactorrhoea) and fertility problems. In men, it may cause reduced libido, erectile dysfunction and, over time, reduced muscle mass and bone density.
A blood test for prolactin levels is the primary diagnostic tool. Levels significantly above the normal range strongly suggest a prolactinoma, and imaging with MRI is then used to confirm and measure the tumour.
Most prolactinomas respond well to medication (dopamine agonists) that reduces prolactin production and shrinks the tumour. Surgery is reserved for cases that do not respond to medical treatment.
Causes of Prolactinoma
Prolactinomas arise from lactotroph cells in the anterior pituitary gland that multiply and form a benign tumour (adenoma). The cause of this abnormal growth is unknown in most cases.
Factors associated with prolactinomas include:
- Multiple endocrine neoplasia type 1 (MEN1), a rare inherited condition that predisposes to tumours in multiple endocrine glands
- Familial isolated pituitary adenomas (FIPA), another inherited susceptibility
It is important to distinguish a prolactinoma from other causes of raised prolactin (hyperprolactinaemia), which include:
- Medications, particularly antipsychotics, antidepressants, anti-sickness drugs and some antihypertensives
- Hypothyroidism
- Pregnancy and breastfeeding
- Other pituitary tumours that compress the pituitary stalk (stalk effect)
- Kidney or liver failure
Prolactinomas are more commonly diagnosed in women (often as microprolactinomas) and in men tend to be larger at diagnosis.
Tests that can help check this condition
Learn more on the official NHS page .
