Prolactin Test: Normal Range, Causes of High Prolactin and Next Steps
Prolactin is a pituitary hormone that stimulates milk production and, when raised, suppresses reproductive hormones. Normal is 4–15 ng/mL in men and 4–23 ng/mL in women. High prolactin causes irregular periods, infertility, milk discharge and reduced libido — but stress, medication and even the needle itself can raise it temporarily.
Hormones & Fertility Panels
1 Parameter
Serum (2 mL)
6 Hours
Preparation & Fasting Guidelines
Detailed Clinical Overview
Prolactin is secreted by the anterior pituitary under continuous inhibition by dopamine from the hypothalamus. Anything that reduces dopamine — dopamine-blocking drugs, a pituitary stalk lesion, or a prolactin-secreting adenoma — raises prolactin. Raised prolactin in turn suppresses GnRH, which lowers LH, FSH, oestrogen and testosterone, producing infertility and menstrual disturbance in women and low libido and hypogonadism in men.
Prolactin is exquisitely sensitive to stress. Venepuncture itself, needle anxiety, breast examination, nipple stimulation, exercise, sleep, a large meal and even prolonged standing all raise it. This is why a modestly raised prolactin — anything up to about 50 ng/mL — should be repeated under rested conditions before any investigation is undertaken.
A further trap is macroprolactin: prolactin bound to immunoglobulin, forming a large complex that is biologically inactive but measured by standard assays. It accounts for a meaningful proportion of apparently raised prolactin results and, when present, requires no treatment at all. Any unexplained hyperprolactinaemia should be checked for macroprolactin before a scan is arranged.
Why Get Tested at QXL Diagnostics?
Frequently Asked Questions
Q: What is the normal prolactin level?
A: 4 to 15 ng/mL in men and 4 to 23 ng/mL in non-pregnant women. Prolactin rises substantially and normally in pregnancy and breastfeeding, reaching 200 to 400 ng/mL, so pregnancy must always be excluded before a raised result is investigated.
Q: What causes high prolactin?
A: Medications are the commonest cause — antipsychotics, metoclopramide, domperidone, some antidepressants, verapamil and opioids. Other causes are hypothyroidism, a prolactin-secreting pituitary tumour, chronic kidney disease, chest wall injury, PCOS, pregnancy, and macroprolactin, which is biologically inactive.
Q: Can stress raise prolactin?
A: Yes, and it does so easily. Venepuncture itself, needle anxiety, exercise, a heavy meal, breast examination, nipple stimulation and disturbed sleep all raise prolactin. This is why a mildly raised result should be repeated after 30 minutes of quiet rest before any further investigation.
Q: When is the best time to test prolactin?
A: Mid-morning, about two to three hours after waking, after resting quietly for 30 minutes. Prolactin peaks during sleep, so an early morning sample taken immediately on waking can be misleadingly high.
Q: What is macroprolactin?
A: Macroprolactin is prolactin bound to an antibody, forming a large complex that standard assays measure but which is biologically inactive. It accounts for a meaningful share of apparently raised prolactin results, causes no symptoms and needs no treatment. Any unexplained hyperprolactinaemia should be screened for it before an MRI is arranged.
Q: What prolactin level indicates a pituitary tumour?
A: Levels above 100 ng/mL, confirmed on a rested repeat with drugs and hypothyroidism excluded, usually indicate a prolactinoma, and above 250 ng/mL suggests a macroadenoma. A pituitary MRI is the confirmatory investigation. Levels between 25 and 50 ng/mL far more often have a benign explanation.
Q: Can high prolactin cause infertility?
A: Yes. Raised prolactin suppresses GnRH, which lowers LH and FSH and prevents normal ovulation in women and reduces testosterone and sperm production in men. It is a well-recognised and highly treatable cause of infertility, which is why prolactin is part of any standard fertility workup.
Q: Does hypothyroidism raise prolactin?
A: Yes. In primary hypothyroidism, increased TRH from the hypothalamus stimulates prolactin release as well as TSH. Correcting the thyroid corrects the prolactin, which is why TSH should always be checked before a pituitary MRI is arranged for a raised prolactin.
Q: How is high prolactin treated?
A: It depends entirely on the cause. If a drug is responsible, the prescriber reviews it. If hypothyroidism is responsible, thyroxine corrects it. A prolactinoma is usually treated medically with cabergoline or bromocriptine, which lower prolactin and shrink the tumour effectively; surgery is needed only in a minority.
Q: Should a single high prolactin result be investigated immediately?
A: No — a rested repeat comes first, along with a pregnancy test, a medication review, a TSH and a macroprolactin screen. A very high level above 100 ng/mL with symptoms such as visual disturbance is different and warrants prompt evaluation, but most mildly raised results resolve on correct repeat testing.
Includes free doorstep home sample collection
Book Home Collection →Or call: +91 9964 639 639NABL Quality Guarantees
NABL Accredited (MC-6849)
ISO 15189:2022 quality compliance
Same-Day Digital Reports
Delivered straight to WhatsApp & Email
Free Doorstep Collection
Sterile vacuum containers & cold-chain kits