Prolactin

A prolactin blood test is used by doctors to evaluate sexual dysfunction or very low testosterone blood levels from unknown causes in both men and women.

Prolactin is a hormone produced in the pituitary gland that is known for supporting lactation in women but also has many other functions in the immune response, such as myelin coating on nerves, and enhancing LH receptors on testicular Leydig cells so that testosterone can be produced. 

What is Prolactin?

Prolactin is a hormone produced in the pituitary gland that is known for supporting lactation in women but also has many other functions on immune response, myelin coating on nerves, and enhancing LH receptors on testicular Leydig cells so that testosterone can be produced. 

Prolactin levels peak during REM sleep and in the early morning. Levels can rise after exercise, meals, sexual intercourse, minor surgical procedures, or epileptic seizures.

In both men and women, the pituitary glands create the hormone prolactin. In women, it is principally in charge of breastfeeding, some types of breast tissue development, and milk production [3]. Prolactin levels, however, can significantly affect sexual performance in men. The impact of elevated prolactin levels on male sexual performance, as well as the ideal prolactin range and its highest levels, will be discussed in this article.

Prolactin levels in men are commonly thought to be best between 2 and 18 ng/mL. It is crucial to remember that typical ranges can change based on the facility doing the test. Prolactin levels can change during the day and with specific activities, such as exercise, and are typically higher in nonpregnant women than in males [3]. The normal range for prolactin in your blood is 2 to 18 nanograms per milliliter (ng/mL) for males. However, it's important to note that pregnant women may have higher prolactin levels, ranging from 80 to 400 ng/mL (80 to 400 µg/L) [Usage Example].

His doctor might advise a prolactin blood test if he displays symptoms of high prolactin levels, such as sexual dysfunction. More testing could be required to identify the underlying reason if the man lacks sexual desire or if he has trouble getting an erection (erectile dysfunction) in addition to high prolactin levels. Treatment can be required in some situations to lower prolactin levels and enhance sexual function. This may entail taking drugs to reduce prolactin production or having any tumors, such as a prolactinoma, surgically removed. In some cases, the blood test may be done to check if a man's testosterone levels are really low and to see whether a prolactinoma is making large amounts of prolactin. In a man, when a pituitary gland problem is suspected, a prolactin test may also be done to check levels if he lacks sexual desire or if he has trouble getting an erection (erectile dysfunction). Prolactin levels may be checked when a man's testosterone levels are really low.

In conclusion, excessive prolactin levels can have a significant impact on men's sexual function. The production of testosterone and other hormones that are crucial for sustaining sexual desire and function can be affected when prolactin levels are too high. Although normal levels can differ depending on the laboratory doing the test, the ideal range for prolactin in men is normally between 2 and 18 ng/mL. If a man displays symptoms of elevated prolactin levels, a doctor may advise a blood test to assess prolactin levels and determine the underlying cause.

Normal Prolactin Ranges:

During pregnancy and postpartum lactation, serum prolactin can increase 10- to 20-fold. Exercise, stress, and sleep also cause transient increases in prolactin levels, including periods of emotional stress. Consistently elevated serum prolactin levels (>30 ng/mL) indicate hyperprolactinemia in the absence of pregnancy and postpartum lactation. Pituitary adenomas, hypothalamic disease, breast or chest wall stimulation, renal failure, or hypothyroidism can cause prolactin hypersecretion. A damaged pituitary gland may not be able to make normal amounts of prolactin so levels will be lower. Several drugs, such as many antidepressants, are also common causes of abnormally elevated prolactin levels. Hyperprolactinemia often results in galactorrhea, amenorrhea, infertility in females, and impotence and hypogonadism in males. Renal failure, hypothyroidism, kidney disease, and prolactin-secreting pituitary adenomas are common causes of abnormally elevated prolactin levels.

Adult Males | 2.0-18.0 ng/mL

Adult Females

Non-Pregnant | 3.0-30.0 ng/mL

Pregnant | 10.0-209.0 ng/mL

Postmenopausal | 2.0-20.0 ng/mL

Prolactin’s Role in Lactation and Breastfeeding

Prolactin is a hormone that plays a vital role in lactation and breastfeeding . It is responsible for stimulating milk production in the mammary glands of the breasts. During pregnancy, levels of prolactin increase significantly to prepare the body for lactation. After giving birth, breastfeeding helps to maintain high levels of prolactin, which promotes milk production and helps to establish milk supply. A prolactin blood test may be recommended for individuals experiencing difficulties with lactation or breastfeeding, as low levels of prolactin can impact milk production.

High Prolactin Consequences

Women are more likely than men to have hyperprolactinemia, or high prolactin levels. However, it can arise from a variety of factors in both sexes. Pituitary tumors, prescription drugs, and other underlying medical disorders are a few factors that can contribute to high prolactin levels in men [4]. Men who have high levels of prolactin may have a variety of sexual issues, such as decreased sperm production, erectile dysfunction, and libido loss [5]. Liver disease, specifically cirrhosis, is another condition that can cause high prolactin levels in both men and women.

Low testosterone production is one of the main ways that excessive prolactin levels have an impact on men's sexual performance. The hormone testosterone maintains men's ability to function and have sexual desire. Prolactin can interfere with the creation of testosterone when levels are too high, which decreases sexual desire and affects erectile function. In men, high levels of prolactin can lead to lower sex drive and erectile dysfunction (ED), also known as impotence, which is the inability to get or maintain an erection [3].

High prolactin levels can impact the levels of other hormones involved in sexual function in addition to lowering testosterone production. For instance, excessive levels of prolactin can inhibit the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH), both of which are crucial for preserving testosterone synthesis and sperm quality in men [3].

High prolactin levels can decrease testosterone and cause sexual dysfunction.

Higher prolactin levels have been associated with tumors involving the lungs, the pituitary gland, and the kidneys. Doctors sometimes use prolactin to evaluate sexual dysfunction of unknown causes in both men and women.

Drugs, supplements, and diseases like pituitary adenomas may disrupt normal prolactin blood levels. These include hypothyroidism, antiepileptics, antidepressants, estrogen, opiates, diuretics, specific growth hormone-releasing peptides, and arginine.

Hyperprolactinemia (Prolactin > 50 ng/dL) is the most frequent abnormality of the anterior pituitary tumors, termed prolactinomas. High blood levels of prolactin are more common than low levels. Prolactinomas may disrupt the hypothalamic-pituitary-gonadal axis as prolactin tends to suppress the secretion of gonadotropin-releasing hormone (GnRH– the hormone responsible for activating the pituitary to male Luteinizing and Follicle Stimulating Hormones (LH and FSH); therefore causing low testosterone and sperm production. Such hormonal changes may manifest as impotence in males. Inappropriate lactation in men is another meaningful clinical sign of prolactinomas (yes, men's breast tissue can produce small amounts of milk if high prolactin blood levels are present).

Modest levels of prolactin elevation (25–50 ng/mL) may be associated with several diagnoses. Primary hypothyroidism and chronic renal disease are associated with elevations in prolactin, probably because of altered metabolism or clearance of prolactin. All other causes of hyperprolactinemia should be excluded before a tumor is considered.

Some medications can increase prolactin blood levels in men, as shown in this table (From Ther Clin Risk Manag. 2007 Oct; 3(5): 929–951.)

What Are Prolactinomas?

Prolactinomas are classified as microadenomas (<10 mm) and macroadenomas (>10 mm). substantial elevation in prolactin (>50 ng/mL) usually indicates a pituitary tumor. Very high levels of prolactin are associated with larger tumors. The finding of a substantial elevation in blood levels of prolactin associated with a pituitary lesion greater than 10 mm by radiographic analysis supports the diagnosis of a macroprolactinoma. An imaging test, such as an MRI, is needed to confirm if a prolactinoma is present.

Other Pituitary Gland Tumors Can Cause High Prolactin

Other pituitary gland tumor types, such as thyroid-stimulating hormone-secreting tumors or growth hormone-secreting tumors, can also result in elevated levels of prolactin. Therefore, if your prolactin levels are high, your doctor may recommend additional tests to determine the cause and appropriate treatment options.

Low Prolactin Consequences:

However, low prolactin blood levels have also been found to be linked to sexual dysfunction and other issues. Since prolactin seems to be involved in immune response and heart muscle integrity, keeping healthy levels is essential.

When Should Men Get a Prolactin Blood Test?

1- Men not on testosterone replacement therapy (TRT) with deficient levels of total testosterone (T level <150 ng/dL), mainly if lower than average LH is observed. For such male patients, testing for prolactin is used as screening for a potential pituitary gland problem (these men are referred to MRI)

2- Men with fluid production from their nipples. This has been observed in some men on anabolic steroids.

3- Men who have been on optimized TRT (TT levels above 500 ng/dL with free testosterone > 2 percent of TT) who complain of erectile dysfunction after at least 8-12 weeks of therapy. Prolactin is not usually included in baseline lab work due to cost, and the incidence of high prolactin in men is about 5 percent, making it not economically justified. However, if total baseline testosterone is very low or optimized, TRT fails to improve ED; prolactin testing could be justified.

Common Questions About the Prolactin Blood Test:

Can prolactin levels fluctuate over time, and if so, how often should someone have this test done?

Prolactin levels can indeed fluctuate over time. Factors such as stress, certain medications, pregnancy, breastfeeding, and even physical exercise can cause temporary increases or decreases in prolactin levels. If your healthcare provider has recommended monitoring your prolactin levels, they will typically guide you on how often you should have this test done based on your specific circumstances. In some cases, regular monitoring may be necessary to track changes in prolactin levels or to assess the effectiveness of treatment for conditions related to abnormal prolactin levels. It is important to follow your healthcare provider's instructions and discuss any concerns or questions you may have regarding the frequency of prolactin testing.

Is there any special diet or fasting required before the prolactin blood test?

It depends on the specific test you are referring to. Some medical tests may require fasting beforehand, while others do not. Fasting before a test is typically done to ensure accurate results, as certain foods and beverages can affect the measurements or levels being tested. It is best to consult with your healthcare provider or the testing facility to determine if there are any specific dietary restrictions or fasting requirements for the test you will be undergoing. They will be able to provide you with the necessary instructions to prepare for the test properly.

What are some reasons why a doctor might order a prolactin blood test?

There are several reasons why a doctor might order a prolactin blood test. Prolactin is a hormone that is primarily responsible for milk production in women who are breastfeeding. However, elevated levels of prolactin can also indicate other underlying health conditions. Some common reasons why a doctor might order a prolactin blood test include:

1. Investigation of fertility issues: High levels of prolactin can interfere with ovulation and menstrual cycles, leading to fertility problems.

2. Evaluation of menstrual irregularities: Prolactin imbalances can cause irregular or absent periods in women.

3. Diagnosis of pituitary gland disorders: The pituitary gland is responsible for producing and regulating prolactin. Abnormalities or tumors in the pituitary gland can lead to overproduction of prolactin.

4. Identification of the cause of galactorrhea: Galactorrhea is the spontaneous production of breast milk outside of pregnancy or breastfeeding. Elevated levels of prolactin can be a cause of galactorrhea.

5. Monitoring the effectiveness of treatment: If a patient has been diagnosed with hyperprolactinemia (elevated levels of prolactin), regular testing may be done to monitor the effectiveness of treatment and ensure that levels are within a normal range.

It's important to note that a prolactin blood test alone cannot provide a definitive diagnosis, but it can help guide further evaluation and treatment if necessary. It's best to consult with your healthcare

References:

[1] "High levels can affect sexual and reproductive health. They may result from medication use, health conditions, or prolactinomas, benign tumors of the pituitary gland. Prolactin plays an important ..." URL: https://www.medicalnewstoday.com/articles/what-are-the-side-effects-of-high-prolactin-levels

[2] "A prolactinoma is the most common cause of hyperprolactinemia. A prolactinoma is a benign (noncancerous) tumor that forms in your pituitary gland and causes excess production of prolactin. In addition to the symptoms of hyperprolactinemia, you may experience the following symptoms if you have a prolactinoma: Headaches. Nausea and/or vomiting." URL: https://my.clevelandclinic.org/health/diseases/22284-hyperprolactinemia

[3] "Prolactin. Prolactin is a hormone that's responsible for lactation, certain breast tissue development and milk production. Higher-than-normal levels of prolactin in your blood can cause certain symptoms, such as irregular periods, infertility and erectile dysfunction. Appointments 216.444.6568." URL: https://my.clevelandclinic.org/health/articles/22429-prolactin

[4] "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 ..." URL: https://www.medicalnewstoday.com/articles/322279

[5] "Symptoms of hyperprolactinemia in males are often harder to recognize because they tend to be more subtle and non-specific than those experienced by females. Symptoms of hyperprolactinemia in males include: Loss of libido. Erectile dysfunction. Infertility (due to decreased sperm production) 2." URL: https://www.verywellhealth.com/what-is-prolactin-2616429

 

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Suggested Reading: Testosterone Replacement Blood Test Targets