Hyperprolactinemia (High Prolactin)

What prolactin does

Prolactin is made by the pituitary gland at the base of the brain. Its main role is milk production after childbirth. Dopamine from the hypothalamus normally keeps prolactin in check. High prolactin suppresses the hormones that drive the ovaries and testes (GnRH, LH and FSH), lowering estrogen and testosterone. That explains most symptoms.

Prolactin rises normally in pregnancy, breastfeeding, sleep, stress, exercise and after nipple stimulation.

Causes

Symptoms

Women

• irregular, infrequent or absent periods (amenorrhea)
• milky nipple discharge (galactorrhea)
• difficulty getting pregnant
• vaginal dryness and pain with sex
• reduced sex drive
• acne or excess hair growth in some

Men

• low libido
• erectile dysfunction
• infertility from low sperm count
• breast enlargement (gynecomastia), rarely nipple discharge
• loss of muscle mass and body hair

Men often present later, with larger tumors.

Tumor-related symptoms

Larger prolactinomas can press on nearby structures, causing headaches, loss of peripheral vision (from pressure on the optic chiasm), double vision, and reduced production of other pituitary hormones.

Long-term effects

Low estrogen or testosterone over time can cause bone loss and osteoporosis.

Diagnosis

1. Prolactin blood test: ideally a rested, non-stressed sample. Mildly raised levels are often repeated.
2. Rule out common causes: pregnancy test, thyroid function, kidney and liver tests, and a medicine review.
3. Macroprolactin testing if levels are raised without symptoms.
4. Pituitary MRI if no medicine or other cause explains the result.
5. Eye field testing for large tumors.
6. Other pituitary hormones for macroadenomas.

Very large tumors can produce falsely low readings in some tests (the "hook effect"); labs can dilute the sample to check.

Treatment

Medicines

Dopamine agonists are first-line treatment for prolactinomas and most symptomatic hyperprolactinemia:

• Cabergoline: usually taken once or twice weekly; more effective and better tolerated.
• Bromocriptine: taken daily; often preferred when trying to conceive, given longer pregnancy safety data.

They normalize prolactin in most people, restore periods and fertility, and shrink most prolactinomas, often within weeks to months. Side effects include nausea, dizziness and headache. Rarely, they cause impulse control problems, such as compulsive gambling or shopping, which should be reported. Some people can stop treatment after 2 years or more of normal levels and tumor shrinkage, with monitoring.

Medicine-induced hyperprolactinemia

If an antipsychotic causes symptoms, your psychiatrist may switch to a prolactin-sparing medicine (such as aripiprazole) or add one. Do not stop psychiatric medicines without medical advice.

Other treatments

• thyroid hormone replacement if hypothyroidism is the cause
• surgery (transsphenoidal, through the nose) for tumors that do not respond or cannot tolerate medicines, or pituitary apoplexy
• radiation rarely
• for people without symptoms or with microadenomas who do not want pregnancy, sometimes monitoring or estrogen replacement to protect bones

Pregnancy

Dopamine agonists are usually stopped once pregnancy is confirmed. People with macroadenomas need monitoring for tumor growth, with vision checks during pregnancy.

Frequently asked questions

What are the symptoms of high prolactin?

In women: irregular or missed periods, milky nipple discharge, infertility, vaginal dryness and low libido. In men: low libido, erectile dysfunction, infertility and breast enlargement. Large pituitary tumors can also cause headaches and vision problems.

What causes hyperprolactinemia?

Common causes are a benign pituitary tumor called a prolactinoma, medicines such as antipsychotics and metoclopramide, an underactive thyroid, kidney disease and pregnancy. Stress and recent exercise can raise levels temporarily.

Is high prolactin serious?

Usually it is treatable and not dangerous. It needs evaluation because of effects on fertility and bones, and because a pituitary tumor may be the cause. Large tumors can affect vision and need prompt treatment.

Can high prolactin be cured?

Often, yes. Stopping a responsible medicine or treating hypothyroidism can normalize prolactin. Prolactinomas usually respond well to cabergoline, and many people can eventually stop treatment. Surgery can cure some small tumors.