Prolactin: The Hormone Blood Test Most People Have Never Heard Of

Quick answer

Prolactin comes from your pituitary gland. This is a small gland at the base of your brain. It is best known for milk production. But it also affects fertility, sex drive, mood, and bone health. Reference range: under 25 ng/mL. A high level can come from certain medicines, stress, or poor sleep. It can also come from a small growth on the gland, called a prolactinoma. Pregnancy and breastfeeding raise it too. Testing it matters most when you have fertility trouble, odd periods, or low sex drive.

What prolactin does

Your pituitary gland makes prolactin. It plays several roles in your body.

For reproduction. It starts milk flow after childbirth. It also quiets ovulation while you breastfeed. At high levels, it can lower fertility overall.

Elsewhere in the body. It helps bone strength. It plays a part in immune function, mood, stress, and sleep.

Healthy ranges

• Women who are not pregnant: under 25 ng/mL
• Men: under 15 to 20 ng/mL
• Pregnancy: rises a lot, over 200 ng/mL by late pregnancy
• Breastfeeding: stays elevated

Reading the number:

• Under 25 ng/mL: normal, for a woman who is not pregnant
• 25 to 50: mildly high
• 50 to 200: moderately high, worth a closer look
• Over 200: significantly high, most often from a prolactinoma

What raises prolactin

Everyday causes. Pregnancy. Breastfeeding. Sleep, since levels peak early in the morning. Stress, both short and long term. Recent sex or nipple touch. Recent hard exercise.

Medicine causes. Certain antipsychotic drugs. Some antidepressants, especially SSRIs. Anti-nausea drugs. Some blood pressure drugs. Opioid painkillers. High-dose estrogen. Some heartburn drugs.

Medical causes. A prolactinoma. This is a small, usually harmless growth on the gland. It is the most common type of pituitary growth. Other pituitary growths can cause it too. So can a severe underactive thyroid, kidney failure, liver failure, or chest wall irritation.

Why prolactin matters

Fertility. High prolactin can quiet ovulation in women. It can cause missed periods. It can make it harder to get pregnant. In men, it can lower sperm count and testosterone. This is a fixable cause of fertility trouble. It is often missed without a specific test.

Cycle changes. High prolactin can cause odd periods, or periods that stop. It can look a lot like perimenopause. It is worth ruling out.

Sex drive. High prolactin lowers sex drive in both men and women. It can cause erectile trouble in men. It can also cause milky discharge from the breast. This can happen in women, and sometimes in men too. In women, this often ties back to lower testosterone. Our testosterone in women guide explains this connection.

Bone health. High prolactin that lasts a long time can weaken bones. This is more likely when estrogen or testosterone also runs low.

Mood. Some research links high prolactin to mild low mood or anxiety.

Common patterns

Pattern 1: From medicine. Prolactin runs 30 to 100 ng/mL. Often tied to antipsychotics, SSRIs, or anti-nausea drugs. A talk with the prescribing doctor can sometimes fix it with a medicine change.

Pattern 2: Prolactinoma. Prolactin often runs over 100, sometimes over 1,000. It may come with headaches or vision changes. A scan of the pituitary gland confirms it. Drugs called dopamine agonists treat it well. Surgery is rarely needed.

Pattern 3: From an underactive thyroid. Prolactin runs mild to moderately high. TSH runs high too. Treating the thyroid usually brings prolactin back to normal.

Pattern 4: From stress. A mild rise. It often settles with rest and less stress. A repeat test in calmer conditions often shows a normal result.

Pattern 5: Macroprolactin. A larger, less active form of prolactin. It can make lab results look high without causing real symptoms. Special testing tells the two apart.

When to test prolactin

Test it during a fertility workup, especially with missed or odd periods. Test it for low sex drive or erectile trouble. Test it for breast discharge that is not from breastfeeding. Test it for headaches with vision changes, or a growth found on a scan. Many full female hormone panels include it as standard.

How to test prolactin properly

Have the sample drawn in the morning, ideally between 8 and 11 AM. Wait at least an hour after waking up. Avoid recent chest or nipple touch. Avoid hard exercise beforehand too. If your first result is mildly high, ask for a repeat test. Stress or recent activity can cause a short-term rise.

What to do about a high result

Mild rise (25 to 50 ng/mL): repeat the test. Review your medicines. Think about stress or sleep as causes. This level often settles on its own.

Moderate rise (50 to 200 ng/mL): your doctor may order a pituitary scan. Expect a careful medicine review, a thyroid check, and kidney and liver tests.

Large rise (over 200 ng/mL): this almost always points to a prolactinoma. Expect a pituitary scan and a referral to a hormone doctor, called an endocrinologist. Dopamine agonist medicine usually works very well.

A full fertility hormone panel includes prolactin alongside the other hormones that affect your cycle. You can book your &you Labs panel to check it as part of your full hormone picture.

Frequently asked questions

Can stress raise my prolactin?

Yes. Both short-term and ongoing stress can raise prolactin a little. If it stays high even when you feel calm, it is worth further testing.

Does high prolactin always mean a tumor?

No. Most mild to moderate rises come from medicine, stress, or an underactive thyroid. A very high result, over 200 ng/mL, almost always points to a prolactinoma.

Can prolactin be too low?

Very low prolactin is uncommon and rarely causes clear symptoms. It can appear when the whole pituitary gland is underactive.

Should men get their prolactin checked?

Yes, if you are working through fertility trouble, erectile issues, or low sex drive. It is not part of routine testing for men without symptoms.

Will a prolactinoma shorten my life?

No. With the right treatment, usually a dopamine agonist medicine, people with a prolactinoma go on to live full, normal lives.

Key takeaways

• Prolactin is a pituitary hormone that affects fertility, sex drive, mood, and bone health.
• Reference range: under 25 ng/mL for women who are not pregnant. It rises a lot during pregnancy and breastfeeding.
• Common causes of a high result include medicine, stress, an underactive thyroid, and prolactinoma.
• It is a reversible, often-missed cause of fertility trouble and low sex drive.
• Treatment, whether dopamine agonist medicine or fixing the root cause, usually works well.