⚠️ Educational only. LabPlain does not provide medical advice or diagnosis. Always discuss your specific results with your healthcare provider.
What this test measures
Prolactin is a hormone made by the pituitary gland — a small gland located at the base of the brain. Its primary role is helping breast development and milk production after childbirth, but prolactin also affects fertility, reproductive hormones, libido, and menstrual cycles.
Both men and women naturally produce prolactin, though levels are typically much higher during pregnancy and breastfeeding. Stress, sleep, exercise, and certain medications can temporarily increase prolactin levels even in healthy people.
Doctors order a prolactin test when investigating irregular periods, infertility, breast discharge, low testosterone symptoms, erectile dysfunction, headaches, or suspected pituitary gland disorders.
Normal reference range
Women: 4–23 ng/mL | Men: 3–15 ng/mL
Reference ranges vary slightly between laboratories, and prolactin levels naturally fluctuate throughout the day. Pregnancy and breastfeeding can raise prolactin dramatically above standard ranges.
Stress before a blood draw — including anxiety about the test itself — can temporarily raise prolactin levels.
⏰ Why timing matters
Prolactin levels are usually highest during sleep and early morning hours. Many doctors prefer morning blood draws because levels are more stable and easier to interpret. Heavy exercise or emotional stress shortly before testing can temporarily increase results.
What your result might indicate
↑ If High
High prolactin (hyperprolactinemia) may result from pregnancy, stress, medications, hypothyroidism, kidney disease, or a pituitary tumor called a prolactinoma. Mild elevations are common and often temporary.
↓ If Low
Low prolactin is less common and usually less concerning. It may occur with pituitary dysfunction, dopamine-enhancing medications, or certain hormonal disorders. Many people with low prolactin have no symptoms.
Symptoms associated with abnormal prolactin
↑ High Prolactin Symptoms
Irregular or missed periods
Breast milk production when not pregnant
Infertility
Low sex drive
Erectile dysfunction
Low testosterone symptoms
Headaches
Vision changes with large pituitary tumors
↓ Low Prolactin Symptoms
Difficulty producing breast milk after childbirth
Possible fertility issues
Hormonal imbalance symptoms
Fatigue
Low libido
Pituitary dysfunction symptoms
Menstrual irregularities
Sometimes no symptoms at all
Common causes of abnormal prolactin
What can raise prolactin?
The most common causes of elevated prolactin are pregnancy, breastfeeding, stress, and certain medications — especially antidepressants, antipsychotics, and some blood pressure drugs. Hypothyroidism can also raise prolactin levels because low thyroid hormone changes pituitary signaling.
More significant elevations may point to a prolactinoma, which is a usually noncancerous pituitary tumor that produces excess prolactin. Kidney disease and chest wall injuries can also increase levels.
What can lower prolactin?
Low prolactin is less frequently discussed because it often causes few symptoms. It may occur with pituitary gland dysfunction or from medications that increase dopamine activity. In rare cases, severe pituitary damage can reduce prolactin production along with other important hormones.
Tests often ordered alongside prolactin
Prolactin is usually interpreted together with other hormone tests. Your doctor may also order:
LH and FSH — reproductive hormones that help evaluate fertility issues
Testosterone — often reduced when prolactin is elevated in men
Estradiol — helps evaluate menstrual and fertility problems
MRI of the pituitary gland — used if a prolactinoma is suspected
What to do next
A single abnormal prolactin result usually does not confirm a serious condition. Prolactin levels are highly sensitive to stress, sleep, exercise, medications, and pregnancy status. Your doctor will interpret the result alongside your symptoms, medical history, and any additional hormone testing. Mild elevations are common and often temporary.
Questions to ask your doctor
01Could stress, sleep, or exercise have affected my prolactin result?
02Are any medications I'm taking known to increase prolactin?
03Should my prolactin level be repeated to confirm the result?
04Do I need additional hormone testing like TSH, testosterone, LH, or FSH?
05Is there any reason to suspect a pituitary gland problem?
06Should I see an endocrinologist for further evaluation?
Frequently asked questions
Can stress alone raise prolactin?
Yes. Emotional stress, lack of sleep, intense exercise, and even anxiety during the blood draw can temporarily increase prolactin levels. Mild elevations are common and often repeated before further testing is done.
Does high prolactin always mean a pituitary tumor?
No. Many cases of elevated prolactin are caused by medications, stress, pregnancy, breastfeeding, or thyroid problems. Very high levels may prompt imaging tests to rule out a prolactinoma, but mild elevations are much more common.
Can high prolactin affect fertility?
Yes. Elevated prolactin can disrupt ovulation and menstrual cycles in women and lower testosterone levels in men, which may reduce fertility and sex drive.
What medications can raise prolactin?
Common medications that may raise prolactin include antipsychotics, antidepressants, opioids, estrogen-containing medications, and some blood pressure drugs. Always review your medication list with your doctor.
Is low prolactin dangerous?
Usually not. Low prolactin is often less clinically significant than high prolactin and may not cause symptoms. However, very low levels can occasionally point to pituitary dysfunction if other hormones are also abnormal.