A person’s fertility can be affected by how much of the hormone prolactin they have in their blood. A doctor can suggest possible treatments after a prolactin level test, which measures the amount in a blood sample.

A note about sex and gender

Sex and gender exist on spectrums. This article will use the terms, “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.

Both males and females produce the hormone prolactin, but it is known for telling the body to make breast milk when someone is pregnant or breastfeeding. Production of prolactin takes place in the pituitary gland.

Prolactin levels steadily increase during pregnancy and remain elevated postpartum in people who are breastfeeding. The levels typically return to normal within 2–3 weeks after birth in nonlactating people and within 6 months postpartum in those who are lactating.

If the levels are higher or lower than the expected level can indicate a problem. Doctors measure the hormone levels in nanograms per milliliter (ng/ml).

Typical normal levels are:

  • females: less than 25 ng/ml
  • males: less than 17 ng/ml

However, the normal range may vary slightly depending on the test and the laboratory performing it.

When levels go below the normal range, this is known as hypoprolactinemia. However, this condition is very rare and usually happens as a result of an underactive pituitary gland. This can also occur due to a rare but serious postpartum complication doctors call Sheehan syndrome, which results in pituitary insufficiency.

High prolactin levels, or hyperprolactinemia, are more common and can have many causes. A prolactin level test is simple and measures the amount of the hormone in the blood. It can check to see if levels are too low or too high.

Doctors will measure prolactin levels to obtain more information about someone’s health. They may check levels of other hormones at the same time.

This information can also help explain the cause of specific medical concerns that could be related to prolactin levels.

There are several reasons to check a person’s prolactin levels, which we outline below.

Males

Specific symptoms affecting males can indicate a problem with prolactin. They include:

Females

In premenopausal people, the following symptoms can indicate excess prolactin:

Individuals that have gone through menopause may not experience symptoms until the condition progresses. Too much prolactin after menopause can lead to hypothyroidism. Symptoms of hypothyroidism include:

Doctors may advise a person to avoid stress as much as possible and not exercise at least 30 minutes before the test. These can raise the prolactin levels in the blood, causing a false result.

A person should avoid stimulating their nipples in the 24 hours before the test for the same reason. In some cases, a person may need to fast before the test.

How does that test work?

The natural levels of prolactin in the body change throughout the day. Levels gradually rise overnight and are at their highest in the morning.

For this reason, a person will usually have to give blood for the test about 3 hours after a person has woken up.

A technician will take a small blood sample from a vein in a person’s arm during the test, which may feel like a small pinch. The technician will then send the sample for testing.

Insurance and cost

Medicare will usually cover blood tests if they are medically necessary. Though private insurance companies are not legally required to provide coverage for hormone testing, many may cover a prolactin level test.

Based on the person’s symptoms, a doctor will usually order a prolactin test if they suspect a problem with the hormone. This means the test is often part of a necessary medical examination.

The cost of the test can vary widely, depending on the test provider. If a person has insurance coverage, the company could cover a range of about $29–525 of the cost.

Without insurance, a person can pay somewhere in the range of $283–675 out-of-pocket, depending on the test, the test provider, and the insurance company.

What do the results mean?

If a person has high prolactin, depending on their levels, they may have an underlying condition that requires treatment. A person will likely need to undergo additional testing for the right diagnosis.

High prolactin levels are normal during pregnancy, and while someone is breastfeeding — they can be as high as 600 ng/ml.

In non-pregnant females or males, doctors consider prolactin between 50–100 ng/ml as moderately high. Most causes of high prolactin will not raise levels above 200 ng/ml.

One exception is a prolactinoma, which could raise prolactin levels as high as 50,000 ng/ml in extreme cases.

Many medical conditions can raise prolactin levels. These include:

Other causes also include:

For females, high prolactin levels can stop the ovaries from making the hormone estrogen.

Low estrogen levels can disrupt the brain signals that go to the pituitary gland. This can affect the gland’s secretion of the hormone gonadotropin, which can stop the menstrual cycle and the egg’s release from the ovary.

A person can experience irregular or absent periods, a lower sex drive, vaginal dryness, and may experience difficulties conceiving.

For men, high levels of prolactin can cause erectile dysfunction and low sex drive.

This effect in men is because prolactin can stop the testes from producing the hormone testosterone. In some cases, it may cause infertility, but this is rare.

A doctor will usually ask about medical history and any drugs a person is taking before they do a prolactin level test.

Treatment for high levels is usually with medication, normally bromocriptine (Parlodel) and cabergoline (Dostinex). If someone has a prolactinoma, medication can usually reduce the size of the tumor.

Medication to treat high levels can cause side effects, such as nausea and stomach issues. Doctors will only gradually increase the amount of medication they prescribe to a person for this reason.

If test results show high prolactin levels, a person may need more tests. If a doctor suspects that a prolactinoma is causing high levels, they may recommend a CT or MRI scan.

Prolactinomas usually remain small, but sometimes they can be large. Small prolactinomas often do not cause other health problems, although they can affect hormone levels. Large prolactinomas can apply pressure on the nerves between the brain and the eye. This can cause problems with vision and headaches.

More rarely, especially if the medication does not work, a person may need surgery or radiation therapy.

Untreated high prolactin can lead to exacerbations in any of the potential symptoms of the imbalance and lead to infertility.

For example, a person’s menstrual cycle can also stop, leading to the inability to conceive. In males, the longer a person goes without treatment, the more they are at risk for a serious negative impact on their fertility.

An untreated prolactinoma can also lead to brittle bones and increase the risk of fractures over time.

Higher levels are normal in pregnant people and those who are breastfeeding. In individuals who are not pregnant or breastfeeding, low prolactin levels are very rare, and raised levels are more common.

Both can indicate an underlying health condition, but high prolactin levels can have many different causes.

The test to measure prolactin levels is simple and can help doctors prescribe the correct medication to reduce levels or provide treatment for an underlying condition that may be causing the raised levels.