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Company
Endocrine & Reproductive
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Currently under review
Pending specialist review and validation.
A prolactin test measures the amount of prolactin, a hormone made by your pituitary gland. Prolactin helps start and maintain milk production after childbirth, and it also affects reproductive health in people of all sexes.
Your prolactin level is influenced by normal biology, such as sleep and stress, and by conditions that affect the pituitary. The test is done on a blood sample, usually taken after you have been resting quietly, to reduce short-term spikes from stress or exercise.
Doctors use prolactin testing to evaluate symptoms like irregular or absent periods, milk discharge from the breasts when not breastfeeding, infertility, headaches, vision changes, low libido, or erectile dysfunction. Results can help determine if a pituitary tumor, certain medicines, thyroid problems, kidney disease, pregnancy, or other causes are involved.
Knowing your prolactin level guides next steps, which may include repeating the test under standardized conditions, checking for interfering forms of prolactin, reviewing medications, or imaging the pituitary. It also helps monitor treatment with medicines that lower prolactin or track recovery after surgery.
Your result is interpreted based on your sex, age, pregnancy status, and how the sample was collected. Mild increases can happen with stress, recent exercise, or poor sleep, and sometimes a repeat test under calmer, fasting conditions is recommended. Some people have a form of prolactin that reads high on certain assays but causes fewer symptoms; labs can check for this if needed.
If your level is higher than expected and confirmed on repeat testing, your clinician may review medicines, screen for thyroid and kidney problems, and consider pregnancy testing when relevant. When results and symptoms suggest a pituitary issue, imaging may be ordered. If your level is lower than expected, your clinician will interpret that in the context of other pituitary hormones and your overall health. Always discuss what the result means for you and whether any follow-up is needed.
Reference intervals vary by laboratory, analyzer, methodology, population, and units. The ranges shown here are for education only. Always interpret your results against the reference interval printed on your own lab report.
Emotional stress, vigorous exercise, and recent sleep can temporarily raise prolactin. Resting quietly before the blood draw helps reduce these short-term effects.
Prolactin follows a daily rhythm and is often higher in the early morning. Many labs prefer a mid-morning, fasting, resting sample to improve consistency.
Antipsychotics, some antidepressants, estrogens, antiemetics, opiates, and certain blood pressure drugs can increase prolactin. Dopamine agonists lower it. Do not stop medicines without medical advice.
Prolactin naturally rises during pregnancy and while breastfeeding. Levels may remain elevated for a time after weaning.
An underactive thyroid and chronic kidney disease can raise prolactin. Treating the underlying condition often improves the prolactin level.
Some people have larger prolactin complexes that can read as elevated on certain assays but cause fewer symptoms. Labs can screen for macroprolactin when results and symptoms do not match.
High-dose biotin supplements and some antibodies can interfere with immunoassays. Your clinician may advise holding biotin before testing to avoid misleading results.
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