What is Prolactin?
Prolactin is a hormone made by the pituitary gland that stimulates breast milk production after childbirth. Outside of pregnancy and breastfeeding, high prolactin can suppress the reproductive hormones LH and FSH, causing infertility, low libido, and menstrual changes in women and low testosterone in men.
Why it matters
Elevated prolactin is a common, treatable cause of infertility, irregular periods, and low testosterone. It is a routine part of evaluating these problems and can reveal a benign pituitary tumor (prolactinoma).
What it measures
Serum prolactin concentration. Levels rise with stress, sleep, meals, and nipple stimulation, so testing conditions matter.
Reference & optimal ranges
Reference ranges vary by lab, assay, age, and sex. The ranges below reflect commonly published adult intervals and are for education only always interpret results with the range printed on your own lab report and a clinician.
High prolactin (hyperprolactinemia) can suppress reproductive hormones and often warrants imaging to rule out a pituitary tumor.
Common symptoms
- Irregular or absent periods
- Milky nipple discharge (galactorrhea)
- Low libido, erectile dysfunction
- Infertility
Potential causes
- Prolactinoma (pituitary tumor)
- Medications (antipsychotics, some antidepressants)
- Hypothyroidism
- Stress, recent meal, or nipple stimulation
- Pregnancy/breastfeeding
Low prolactin is uncommon and rarely clinically significant, occasionally seen with pituitary underactivity.
Common symptoms
- Usually none
Potential causes
- Hypopituitarism
- Certain medications (dopamine agonists)
How to improve your Prolactin
Lifestyle
Note testing conditions
Avoid nipple stimulation and heavy stress before testing; a fasting morning draw is preferred.
Nutrition
General balanced diet
No specific diet lowers prolactin; treat the underlying cause.
Exercise
Regular activity
Supports overall pituitary and reproductive health.
Sleep
Consistent sleep
Prolactin rises during sleep; test after being awake a few hours.
Frequently asked questions
Scientific references
- Prolactin Levels Test Testing.com
- Prolactin Levels Test MedlinePlus, U.S. National Library of Medicine
Educational information, not medical advice. This page is for general education and does not replace diagnosis or treatment by a licensed clinician. Do not start, stop, or change any medication, supplement, or treatment based on this content. Reference and optimal ranges vary between laboratories interpret your results with the range on your own report and a qualified professional.