High prolactin: what it means and what to do

A high prolactin needs confirming first: the stress of the blood test is enough to raise it. If it stays high, your doctor looks for the cause. Often it is a medicine or the thyroid. When it is a small pituitary growth, it is usually benign and treated with medicines.

What high prolactin means

It means your blood holds more prolactin than the limit on your report. The medical name is hyperprolactinaemia.

How high it is matters. Just above the limit, stress, medicines or the thyroid are often behind it. With medicines it usually stays below 100 ng/mL, though a few raise it further. Above 250 there is usually a prolactinoma.

A high prolactin does not mean cancer. A prolactinoma is almost always benign and responds well to treatment.

What causes high prolactin

The cause is often simple. The most common come first.

• Pregnancy and breastfeeding: Prolactin rises, and that is normal. If your period is missing, the first step is to rule out pregnancy.
• Stress and the blood test: Anxiety, pain or a difficult draw raise it for a short while.
• Medicines: Antipsychotics, some antidepressants, metoclopramide and domperidone, some blood pressure medicines. Do not stop them on your own: talk to your doctor.
• Macroprolactin: A large, inactive form that raises the number but causes no symptoms.
• An underactive thyroid: Hypothyroidism can raise it. Treating the thyroid brings it down.
• Kidneys: If your kidneys work much less well, prolactin builds up.
• The pituitary gland: A prolactinoma, a benign growth that makes it, or another growth pressing on the pituitary.

Symptoms of high prolactin

Sometimes it causes no symptoms. When it does, the most common are:

• In women: irregular or missing periods, milk from the nipple, trouble getting pregnant
• In men: erection problems, growing breasts
• In both: lower sex drive, weaker bones if it lasts a long time
• If the growth is large: headaches and less vision at the sides

If you have these symptoms, talk to your doctor.

High prolactin and the pituitary

A prolactinoma is the most common of the pituitary growths that make hormones. It is benign, and often small.

It is usually treated with tablets that lower prolactin and often shrink the growth. Surgery is rarely needed.

If prolactin is high without a clear reason, your doctor may ask for an MRI scan of the pituitary.

Which tests to read alongside it

These tests help show where it comes from.

How to lower your prolactin

It depends on the cause. Where to start:

• Repeat the test at rest, as your lab advises. Often the second result is normal.
• Rule out pregnancy if your period is missing.
• Bring your doctor the list of medicines you take. If one of them raises it, your doctor decides whether to change it.
• Ask to have your thyroid and kidneys checked.
• If it stays high without a clear reason, your doctor refers you to an endocrinologist.

No food or supplement lowers it reliably. If there is a prolactinoma, the endocrinologist decides the treatment.

High prolactin: when to worry

Talk to your doctor if:

• Your prolactin is high on a second test taken at rest.
• Your periods have stopped for months or milk comes from your nipple.
• You are a man with low sex drive or erection problems.
• It is above 250 ng/mL: see your doctor soon.
• You have headaches that do not go away or you see less at the sides: see your doctor soon.
• You have a sudden, very severe headache with worsening vision: call 112 or go to the emergency department.

Frequently asked questions

What are the symptoms of high prolactin? In women, mostly irregular or missing periods and milk from the nipple. In men, low sex drive and erection problems. Sometimes there are no symptoms.

When is high prolactin a worry? If it stays high on a second test and you have symptoms, talk to your doctor. Above 250 ng/mL, or with headaches and vision problems, see your doctor soon.

Can stress raise prolactin? Yes. Even the anxiety of the blood test raises it a little. That is why a slightly high result is repeated at rest.

What does high prolactin mean in men? It can lower testosterone and cause low sex drive and erection problems. The causes are the same as in women: medicines, thyroid, kidneys, sometimes a pituitary growth.

Can I get pregnant with high prolactin? A high prolactin can stop ovulation and make it harder to get pregnant. With treatment, periods often come back. Talk to your gynaecologist.

What is macroprolactin? A large form of prolactin bound to antibodies. It raises the number on your report but does not act and causes no symptoms. A specific test picks it up.

Sources

• Melmed and colleagues, diagnosis and treatment of hyperprolactinemia: an Endocrine Society clinical practice guideline. Journal of Clinical Endocrinology and Metabolism, 2011. PMID 21296991
• Petersenn and colleagues, diagnosis and management of prolactin-secreting pituitary adenomas: a Pituitary Society international consensus statement. Nature Reviews Endocrinology, 2023. PMID 37670148