Prolactin Test
A blood test that measures prolactin, a hormone involved in breast milk production.
Quick Summary
To investigate irregular periods, infertility, breast milk discharge or low sex drive.
Prolactin level.
Ideally a morning sample, rested; stress and some medicines raise it.
Overview
High prolactin can stop ovulation and periods.
Causes include some medicines, thyroid problems and small pituitary tumours.
What It Measures
Prolactin
Blood level.
How It's Performed
- 01
Preparation
Usually no special preparation. Tell the staff about medicines you take.
- 02
Blood sample
A small amount of blood is taken from a vein in your arm with a thin needle.
- 03
Afterwards
Press on the spot for a minute. A small bruise is common; you can go back to normal activities.
Reference Ranges
Note: Normal ranges vary by laboratory. Consult your report for the specific reference used.
| Parameter | Typical Range (Adult) | Units |
|---|---|---|
| Prolactin (women) | Below 25 | ng/mL |
| Prolactin (men) | Below 15 | ng/mL |
Interpreting Results & Next Steps
Discuss with Doctor
Normal ranges differ between laboratories, ages and sexes; always use the range printed on your report and ask your doctor what your results mean.
If values are High:
High prolactin can cause irregular periods and infertility.
Sources and further reading
Last updated 21 October 2026. For more detail, see these trusted health organisations.
- Prolactin Levels(opens in a new tab) · MedlinePlus, US National Library of Medicine