All About PRL Blood Test and Its Impact on Prolactin Levels

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What is a Prolactin Test?

A prolactin (PRL) test measures the amount of prolactin in your blood. Prolactin is a hormone generated by the pituitary gland, a tiny organ situated at the brain's base. Hormones act as chemical messengers in the bloodstream, regulating various cellular and organ functions.

Prolactin plays a crucial role in various bodily functions, especially in stimulating breast tissue growth during pregnancy and milk production after childbirth. Consequently, prolactin levels are typically high in pregnant women and new mothers.

In contrast, nonpregnant women and men usually have low prolactin levels.


Elevated prolactin levels (hyperprolactinemia) can have different impacts:


  • In women: It can affect ovarian function, leading to menstrual irregularities and infertility.
  • In men: It can impact testicular function, causing a reduced sex drive and erectile dysfunction (ED).
  • In nonpregnant, non-breastfeeding individuals: It may trigger unexpected breast milk production.

Various factors can cause elevated prolactin levels, including:

  • Prolactinoma: A benign tumor on the pituitary gland, the most common cause, which increases prolactin production.
  • Medications: Certain drugs can elevate prolactin levels.
  • Medical Conditions: Hypothyroidism, kidney disease, and chest injuries can contribute.
  • Other Pituitary Tumors

A prolactin test alone cannot pinpoint the cause of high prolactin levels. However, it helps healthcare providers determine the need for further testing to diagnose the underlying issue.


Other Names:

PRL test, prolactin blood test


What is it Used For?

A prolactin test, often combined with other tests, helps:

  • Diagnose prolactinoma.
  • Identify the cause of irregular menstrual periods.
  • Determine the reason for infertility in both men and women.
  • Investigate the cause of a man's low sex drive and/or erectile dysfunction.
  • Monitor prolactinoma treatment effectiveness or tumor recurrence.

Why Do I Need a Prolactin Test?

You might need a prolactin test if you exhibit symptoms indicative of elevated prolactin levels. Symptoms differ between women and men.


In women, symptoms might include:


  • Menstrual changes (irregular or absent periods)
  • Breast milk production without pregnancy or breastfeeding
  • Nipple discharge
  • Infertility

Symptoms also vary based on menopausal status, typically around age 50.


In men, symptoms might include:


  • Nipple discharge
  • Erectile dysfunction (impotence)
  • Enlarged breasts (gynecomastia)
  • Decreased facial and body hair
  • Low sex drive

For those with a prolactinoma, additional symptoms may occur if the tumor presses against nearby pituitary gland parts or the brain, causing:


  • Headaches
  • Vision changes if pressing on the optic nerve
  • Reduced levels of other hormones produced by the pituitary gland, including thyroid hormones and cortisol

If diagnosed with high prolactin levels due to a prolactinoma, regular prolactin testing might be necessary to evaluate treatment efficacy and check for tumor recurrence.


What Happens During a Prolactin Test?

A healthcare professional will draw a blood sample from a vein in your arm using a small needle. A small amount of blood is collected into a test tube or vial, causing a brief sting when the needle is inserted and removed. The process typically takes less than five minutes.


Preparation for the Test

Your provider will inform you if any preparation is needed. You may be asked to fast (avoid food and drink) for several hours before the test. Prolactin levels fluctuate throughout the day, so the blood sample is usually taken three to four hours after waking.

Certain medications and vitamins can affect prolactin levels. Inform your provider about anything you're taking, but never stop any medication without consulting your provider.


Risks of the Test

Blood tests carry minimal risk. You may experience slight pain or bruising at the needle insertion site, but these symptoms usually resolve quickly.


Understanding the Results

To interpret your prolactin test results, your provider will consider your symptoms, sex, medical history, and other test results.

In general, elevated prolactin levels in nonpregnant, non-breastfeeding individuals may indicate:

  • Prolactinoma or another pituitary disorder
  • Hypothalamus disease (the brain area controlling the pituitary gland)
  • Hypothyroidism
  • Cirrhosis (liver scarring)
  • Kidney disease
  • Polycystic ovary syndrome (PCOS) in women

If your results show high prolactin levels, additional blood tests or an MRI may be needed to diagnose the cause. Treatment for high prolactin levels varies based on the underlying cause, often involving medication or, in some cases, surgery for pituitary tumors.

Elevated prolactin levels don't always indicate a medical issue requiring treatment. High-protein diets, certain medications, stress, exercise, and sex can cause temporary increases. Your provider may suggest retesting to confirm consistently high levels.

Low prolactin levels are rare but may indicate a pituitary disorder, potentially affecting milk production after childbirth.



Understanding prolactin levels is vital for diagnosing and managing various health conditions that can affect both women and men. While elevated levels can indicate significant health issues like prolactinoma or other pituitary disorders, they can also result from less concerning factors such as diet, stress, or medication. Accurate diagnosis often requires a combination of prolactin testing and additional examinations. By working closely with your healthcare provider, you can determine the underlying cause of abnormal prolactin levels and receive appropriate treatment, ensuring better overall health and well-being.