High Prolactin Levels: What Does a Raised Result Mean and What Happens Next?

High prolactin levels mean the prolactin in your blood sample was above the laboratory's reference range. Prolactin is a hormone made by the pituitary gland at the base of the brain, and it mainly supports breast milk production. A raised result can be temporary, caused by medicines or other conditions, or a sign of a benign pituitary tumour called a prolactinoma, so it needs interpreting in context.

This guide is for adults reviewing a prolactin result that has already been reported. It explains common terms and the usual next steps. It cannot tell you why your own level is high or which tests you need.

Most people with a raised prolactin do not need emergency care. However, MedlinePlus advises going to an emergency department or calling local emergency services for a sudden severe headache, vision loss, double vision or a drooping eyelid, or low blood pressure with fainting, nausea or vomiting. These can be signs of pituitary apoplexy, a rare bleed into the pituitary gland. Seek help right away if you already know you have a pituitary tumour.

Arrange a prompt appointment rather than waiting for a routine retest if you notice gradually worsening headaches, blurred vision or reduced side (peripheral) vision. Large prolactinomas can press on the nerves to the eyes.

Some people have no symptoms at all and find out from a routine test. NIDDK and Cleveland Clinic describe these common symptoms:

• Women: irregular or absent periods not explained by menopause, milky nipple discharge when not pregnant or breastfeeding, difficulty getting pregnant, low sex drive, and vaginal dryness that can make sex painful.
• Men: low sex drive, erection problems, enlarged breast tissue and, linked to low testosterone, reduced fertility. Men often notice symptoms later, so a tumour may be larger when found.
• Anyone: reduced bone density over time. Larger tumours can also cause headaches and vision changes.
• NIDDK notes that women taking hormonal contraception or hormone therapy, or after menopause, may not notice period or breast changes.

Yes. Prolactin can rise for a short time. MedlinePlus and NIDDK list emotional or physical stress, a painful blood draw, recent exercise, eating, sexual activity, nipple stimulation or a recent breast examination. Pregnancy and breastfeeding raise prolactin normally. MedlinePlus notes that if prolactin is high, the test may be repeated in the early morning after fasting.

Macroprolactin is a larger form of prolactin that stays in the blood for longer. The Endocrine Society guideline describes it as less biologically active, which is why it may cause a high reading without symptoms. The guideline suggests checking for macroprolactin when a high result comes without typical symptoms. Ask whether your laboratory has done this check.

Other recognised causes include medicines that affect dopamine, such as some antipsychotics, anti-sickness medicines, opioids, some antidepressants and some blood pressure medicines; an underactive thyroid; chronic kidney or liver disease; chest wall injury or shingles on the chest; and other pituitary or hypothalamus problems. Sometimes no cause is found. Do not stop or change a prescribed medicine to lower prolactin unless your prescriber advises it.

MedlinePlus gives typical normal values below 20 ng/mL for men, below 25 ng/mL for non-pregnant women and below 500 ng/mL in pregnancy. Ranges vary between laboratories, and many report prolactin in different units, such as mIU/L, so compare your number with the range on your own report.

The size of the rise is only one part of the picture. MedlinePlus notes that interpreting a high result is complex and that most people are referred to an endocrinologist, a hormone specialist.

If a high prolactin is confirmed and medicines, pregnancy, thyroid problems and kidney disease do not explain it, a pituitary MRI is the preferred scan to look for a prolactinoma, according to NIDDK. A CT scan may be used if MRI is not suitable, for example with some implants.

Other tests may include thyroid function, other pituitary hormones and, for men, testosterone. MedlinePlus notes that an underactive thyroid can mimic a prolactinoma. Depending on tumour size, a vision test may also be arranged.

Prolactinomas are benign and are the most common type of pituitary tumour. NIDDK describes most as treatable with medicine, and some people with high prolactin but few symptoms may not need treatment. Decisions about treatment are made with a specialist.

Bring the full report and a list of everything you take. These questions can help you leave with a clear plan:

• What was my prolactin value, in what units, and what reference range did the laboratory use?
• Was the sample taken under calm conditions, and should it be repeated? Do I need to fast or come at a particular time?
• Has macroprolactin been checked, and would it change the plan?
• Could any of my medicines, a thyroid problem, kidney disease or pregnancy explain the result?
• Do I need a pituitary MRI, a vision test or a referral to an endocrinologist?
• Which symptoms should make me seek care before the next planned test?

On SameCase, patients and verified doctors share de-identified cases. Reading how others with a raised prolactin described their path, such as a repeat sample, a macroprolactin check, thyroid tests or an MRI, can help you notice questions you had not thought to ask. Another person's results cannot explain yours or tell you what you have. Use what you read to write questions for your own clinician, and see our guide on comparing a similar case with your own.

Keep each prolactin result with its date, time of day, units and reference range, and note any stress, exercise, illness or new medicines around the test. If no one has explained the result or arranged a repeat, contact the team that ordered it and ask who is responsible for follow-up. If an MRI is planned and scans worry you, see our guide on MRI claustrophobia.