Understanding prolactin and the prolactin test
Prolactin is produced by the pituitary gland in the brain. It’s also known as PRL or lactogenic hormone. Prolactin is mainly used to help women produce milk after childbirth.
It’s important for both male and female reproductive health. The specific function of prolactin in men is not well-known. However, prolactin levels have been used to measure sexual satisfaction in both men and women. A prolactin level test can reveal other issues caused by the hormone.
Why is the prolactin test done?
Women with prolactinoma symptoms may need the test. Prolactinoma is a noncancerous tumor on the pituitary gland that produces high levels of prolactin.
Symptoms of prolactinoma in women include:
- unexplained headaches
- visual impairment
- galactorrhea, or lactation outside of childbirth or nursing
- pain or discomfort during sex
- abnormal growth of body and facial hair
- abnormal acne
The test is usually performed on people with prolactinoma to keep track of the tumor’s response to treatment.
Men may need the test if they display symptoms of prolactinoma. Symptoms of prolactinoma in men include:
- unexplained headaches
- visual impairment
- reduced sex drive or fertility problems
- erectile dysfunction
- abnormal lack of body and facial hair
The test may also be used to:
- investigate testicular dysfunction or erectile dysfunction
- rule out problems with the pituitary gland or hypothalamus
How is the test carried out?
A prolactin test is just like a blood test. It takes a few minutes at your doctor’s office or in a lab. You don’t need to prepare for it. The sample is typically collected three to four hours after waking up in the morning. Blood is drawn from a vein in your arm. There’s very little pain. You may only feel a slight pinch when the needle goes in and some mild soreness afterward.
Some birth control pills, high blood pressure drugs, or antidepressants can affect the test results. Tell your doctor about any medications you’re taking before the test is done. Sleeping problems, high stress levels, and strenuous exercise before the test can also influence the results.
What are the risks?
The prolactin test carries little risk of complications. You might get a small bruise at the puncture site after blood is drawn. Keep pressure on the site for a few minutes after the needle is removed to help reduce bruising. You may feel faint or lightheaded.
In rare cases, the vein can become inflamed after the test, in a condition known as phlebitis. Treat phlebitis with a warm compress applied to the site several times a day.
What are normal results?
Your doctor will assess whether your results are normal based on many factors, including your general health. Prolactin values can vary slightly among different labs. Normal results usually look like the following (ng/mL = nanograms per milliliter):
|Women who are not pregnant||< 25 ng/mL|
|Women who are pregnant||34 to 386 ng/mL|
|Males||< 15 ng/mL|
What do high levels mean?
Low levels of prolactin are usually not a concern in women or men. However, very high levels of prolactin, known as hyperprolactinemia, can indicate a deeper issue. About 10 percent of the population has hyperprolactinemia.
High levels of prolactin are normal during pregnancy and after childbirth during nursing. However, hyperprolactinemia can also be caused by anorexia nervosa, liver disease, kidney disease, and hypothyroidism. Hypothyroidism can cause enlargement of the pituitary gland, which is treatable with thyroid hormone replacement therapy. High levels of prolactin can also be caused by pituitary tumors. These tumors can be treated medically or surgically.
Certain medications can cause high prolactin levels. Psychiatric drugs such as risperidone and haloperidol can increase your levels. Metoclopramide can also raise your prolactin levels. This medication is normally used to treat acid reflux or nausea caused by cancer drugs.
Some common stressors can also raise prolactin levels. These stressors include low blood sugar, strenuous exercise activities, and even mild forms of discomfort. If you find out that your prolactin levels are high, you may need to find ways to reduce your stress and keep your blood sugar at consistent levels.
Red clover, fenugreek, or fennel can raise your prolactin levels. Avoid eating anything with these ingredients if you find out you have high prolactin levels.
Prolactin and fertility
In some cases, high prolactin levels can lead to infertility. Prolactinoma tumors can put pressure on your pituitary gland and stop the production of hormones. This condition is known as hypopituitarism. In men, this causes a lower sex drive and a loss of body hair. In women, it can lead to infertility.
Hyperprolactinemia can make it difficult for a woman to get pregnant. High prolactin levels can interrupt the normal production of the hormones estrogen and progesterone. This can cause the ovaries to release eggs irregularly or stop altogether.
Medications and other prolactinoma treatments help restore fertility in most women. If you find out you have high prolactin levels or prolactinoma tumors, talk to your doctor right away about treatments. You can also ask about removing or reducing tumors.
Treatment for high prolactin levels
Dopamine agonists such as bromocriptine (Parlodel and Cycloset) are the most common treatment for high levels of prolactin. These medications help the brain produce dopamine to control high prolactin levels. They can also shrink prolactinoma tumors.
Your doctor may recommend that you take cabergoline. Cabergoline is a newer prolactinoma treatment with milder side effects than other common prolactinoma medications. Talk to your doctor about cabergoline if you face severe side effects from other treatments, including bromocriptine.
Not everyone’s prolactin levels will respond well to dopamine agonists. Your doctor may suggest radiotherapy if those medications don’t help your prolactin levels or prolactinoma.
Your doctor may suggest surgery if medication doesn’t shrink your tumor. Surgery can be performed through the nose or the upper skull. Surgery and medication together can bring your prolactin levels back to normal.
Other steps you can take to lower your prolactin levels include:
- changing your diet and keeping your stress levels down
- stopping high-intensity workouts or activities that overwhelm you
- avoiding clothing that makes your chest uncomfortable
- avoiding activities and clothing that overstimulate your nipples
- taking vitamin B-6 and vitamin E supplements
Vitamin B-6 is part of the dopamine production process, and higher levels can reduce prolactin levels. Vitamin E naturally prevents rises in prolactin levels. Talk to your doctor or nutritionist before changing your intake of vitamins or other supplements.
Your doctor will likely refer you to an endocrinologist if you have a condition related to high prolactin levels. An endocrinologist can help guide you through treatment or surgeries.
Your doctor may request an MRI scan to check if a prolactinoma tumor is causing your prolactin levels to rise. Your doctor will prescribe medication to shrink any existing tumor.
Sometimes there’s no specific cause for your high prolactin levels. This is known as idiopathic hyperprolactinemia. It usually goes away without treatment after several months. If your prolactin levels do not go down, your doctor will likely prescribe medication.
It’s possible to get pregnant while you receive treatment for high prolactin levels. If this happens, tell your doctor or endocrinologist right away. They may tell you to stop taking your medication. However, don’t stop taking your medication until you’re told to do so.
Prolactinoma and hyperprolactinemia are not life-threatening. The worst side effects of medications usually go away after treatment. Infertility caused by high prolactin levels can be reversed once prolactin levels return to normal. Your quality of life will remain high even if you need long-term treatment.