Prolactin levels: what the number means and what to do next

One blood test can explain missed periods, unexplained milk production, low sex drive, or infertility. Prolactin is a hormone made by the pituitary gland. It’s normal to be higher during pregnancy and breastfeeding, but outside that it can point to something worth checking.

Typical lab ranges vary, but nonpregnant women are usually around 5–25 ng/mL and men about 2–18 ng/mL. Small differences between labs happen, so always compare with the lab’s reference range. If your level comes back abnormal, here’s a clear, practical way to think about it.

Common causes and what they look like

High prolactin (hyperprolactinemia) can come from several sources: medications (antipsychotics like risperidone or haloperidol, anti-nausea drugs such as metoclopramide or domperidone, some antidepressants), thyroid problems (untreated hypothyroidism raises prolactin), and pituitary tumors called prolactinomas. Stress, heavy exercise, and nipple stimulation can give a temporary bump too.

Symptoms you might notice: missed periods or irregular cycles, milky discharge from the nipples (galactorrhea), low libido, erectile dysfunction in men, and trouble getting pregnant. Very high levels or large tumors can cause headaches or vision changes — that’s a red flag to get urgent care.

Testing, diagnosis, and next steps

To get a reliable result, have blood drawn in the morning, fasting if possible, and avoid nipple stimulation or intense exercise beforehand. Labs sometimes report a mild rise; if it’s borderline, your doctor will usually order a repeat test plus a TSH to rule out hypothyroidism. If the number is mildly raised (for example 25–100 ng/mL), medications or thyroid issues are common causes. Levels over ~100 ng/mL often prompt imaging (MRI of the pituitary) to check for a prolactinoma. Labs can also screen for macroprolactin — a larger form of the hormone that inflates numbers but usually has fewer symptoms.

Treatment depends on the cause. If a drug is the culprit, your clinician may switch medications or adjust dose. For prolactinomas, dopamine agonists (cabergoline or bromocriptine) are the first-line treatment and shrink many tumors while lowering prolactin. Surgery or radiation is reserved for tumors that don’t respond or press on optic nerves. For hypothyroidism, treating the thyroid typically brings prolactin back to normal.

Practical tips: bring a list of all pills and supplements to your appointment, ask the lab to check for macroprolactin if symptoms don’t match the number, and insist on an MRI if levels are high or you have vision changes. If you’re trying to conceive and prolactin is high, call your doctor — lowering prolactin often restores ovulation and improves chances quickly.

If anything feels urgent — sudden vision loss, severe headache, or very high prolactin confirmed on repeat testing — seek care right away. For most people, a little testing and the right treatment get things back to normal without surgery. Ask questions, keep a short symptom diary, and work with your clinician to pick the safest plan for you.