Prolactin
Also called PRL
Prolactin is a hormone made by the pituitary gland whose main job is to make breast tissue grow during pregnancy and produce milk after birth. Outside pregnancy and breastfeeding, levels are normally low in both women and men, and a prolactin blood test checks whether they are.
A raised level, called hyperprolactinemia, can interfere with the ovaries or testicles. In women it can disrupt periods and fertility; in men it can lower sex drive and cause erectile difficulty. The most common cause is a benign pituitary tumor called a prolactinoma, but certain medicines, an underactive thyroid and kidney disease can also raise it. Levels change through the day, so the draw is usually timed a few hours after waking.
Why it matters after 45
Prolactin is usually tested as part of working out why testosterone is low. The American Urological Association recommends measuring it in men whose testosterone is low while LH (luteinizing hormone) is low or low-normal, because a high prolactin level can suppress LH and, with it, testosterone. Persistently raised levels without a clear cause call for a fuller endocrine evaluation.
Where it comes up
Related terms
References
- MedlinePlus. Prolactin Levels. U.S. National Library of Medicine. https://medlineplus.gov/lab-tests/prolactin-levels/
- American Urological Association. Evaluation and Management of Testosterone Deficiency (AUA Guideline). https://www.auanet.org/guidelines-and-quality/guidelines/testosterone-deficiency-guideline
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