Hormone Test

Prolactin Blood Test

Name: Prolactin Blood Test: Normal Range & High | HealthReview
Creator: Suman Konda
Published: 2026-07-05

Prolactin is a hormone produced by the pituitary gland that stimulates breast milk production. Abnormally high levels can cause infertility, irregular periods and vision problems in both men and women.

Written and clinically reviewed by Suman Konda, PharmD, Clinical Pharmacist · Based on peer-reviewed sources · Editorial policy · Not medical advice

Last reviewed and updated: 01 August 2026 · How we check our content

What is prolactin?

Prolactin is a hormone made by the anterior pituitary gland, located at the base of the brain. Its primary function is to stimulate and maintain breast milk production (lactation) after childbirth. In men and non-pregnant women, prolactin is present in small amounts. Levels naturally rise during pregnancy and breastfeeding. Elevated prolactin (hyperprolactinaemia) outside of pregnancy suppresses reproductive hormones, causing infertility and other symptoms.

Prolactin normal range

Group	Normal Range (ng/mL or mIU/L)
Non-pregnant women	2 – 29 ng/mL
Men	2 – 18 ng/mL
Pregnant women	10 – 209 ng/mL (varies by trimester)
Breastfeeding women	Up to 300 ng/mL

HIGH Prolactin: Hyperprolactinaemia

Causes: prolactinoma (a benign pituitary tumour that overproduces prolactin, the most common cause of pathological elevation), medications (antipsychotics, metoclopramide, domperidone, some antidepressants, opioids, antihypertensives like methyldopa and verapamil), hypothyroidism (high TRH stimulates prolactin release), kidney disease (reduced clearance), liver cirrhosis, chest wall injury or breast stimulation. Symptoms in women: irregular or absent periods (amenorrhoea), milky nipple discharge (galactorrhoea) unrelated to breastfeeding, infertility, decreased libido. Symptoms in men: reduced libido, erectile dysfunction, infertility, gynecomastia (breast tissue growth). Very large prolactinomas can compress the optic chiasm causing visual field loss.

When is a pituitary MRI needed?

A prolactin level above 100 ng/mL strongly suggests a prolactinoma and warrants a pituitary MRI to look for a tumour. Levels of 25–100 ng/mL can have many causes (medications, hypothyroidism, stress) and are investigated based on clinical context. Very high levels (>500 ng/mL) almost always indicate a large prolactinoma (macroprolactinoma).

Treatment of prolactinoma

Most prolactinomas are treated with dopamine agonist medications, cabergoline or bromocriptine, which are highly effective at lowering prolactin and shrinking the tumour. Surgery is rarely needed. Regular prolactin monitoring is used to track treatment response.

Questions to ask your doctor

Should I have a pituitary MRI?
Is a medication causing my high prolactin?
Should I check my thyroid (TSH)?
Can high prolactin be treated with medication alone?
Will my fertility return once prolactin is normalised?

Frequently asked questions

Why does my lab's Prolactin range differ from the one shown here?

Every laboratory sets its own reference interval from the analyser, reagents and reference population it uses, so two labs can publish different Prolactin intervals and both be correct, even reporting in the same ng/mL. Read your result against the range printed on your own report.

Should a borderline Prolactin result be repeated?

Usually. A value just outside the interval is common in people who are entirely well, since about one in twenty healthy results falls outside any 95% reference range by construction. A borderline Prolactin is normally rechecked rather than acted on.

Is a slightly abnormal Prolactin a reason to worry?

Rarely on its own. Reference intervals are built to contain the middle 95% of a healthy population, so mild deviations are common in well people. The size of the deviation, its direction over time and your symptoms decide whether it means anything.

References

The clinical information on this page is drawn from peer-reviewed sources indexed by the US National Library of Medicine. Links go to the source so you can read it yourself.

Hyperprolactinemia. In: StatPearls. Treasure Island (FL): StatPearls Publishing. NCBI Bookshelf NBK537331