Definition

Prolactin is a hormone primarily involved in lactation, the development of certain breast tissues, and a variety of other physiological processes. Prolactin levels are typically low in men and non-pregnant, non-lactating individuals, but they increase significantly during pregnancy and breastfeeding. This hormone is produced and released by the pituitary gland, a small pea-shaped structure located in the brain beneath the hypothalamus. The pituitary gland is a key component of the endocrine system, playing a crucial role in regulating numerous hormones, including prolactin.

The production and release of prolactin are regulated by dopamine, a neurotransmitter in the brain, and the hormone estrogen. Factors such as nipple stimulation, exercise, and stress can also stimulate prolactin production. While prolactin contributes to many body functions, its primary role is to support the development of mammary glands in breast tissue, promote milk production, and facilitate lactation and breastfeeding.

Indications

Prolactin tests are used to help diagnose conditions such as prolactinoma, a type of tumor in the pituitary gland, as well as identify the causes of menstrual irregularities or infertility in women. In men, the test can help determine the underlying causes of reduced sexual desire or erectile dysfunction.

Doctors may recommend a prolactin test in women presenting with irregular menstrual cycles, absence of menstruation, infertility, or unexpected milk discharge from the breasts when not pregnant or breastfeeding. Other reasons for the test include identifying soft lumps in the breast or evaluating symptoms of menopause syndrome.

In men, this test may be advised if there is a noticeable decrease in sexual desire, difficulty achieving an erection, or breast enlargement. Rarely, it may also be used to investigate cases where men produce breast milk.

Contraindications

There are no specific contraindications for a prolactin test, making it generally safe for most individuals.

Preparations Prior to Test

There is no need for special preparation before undergoing a prolactin test. Fasting is not required for this test, but it is typically performed 3–4 hours after waking up since prolactin levels are highest in the morning and fluctuate throughout the day. Patients should inform their doctor if they are taking medications such as birth control pills, antihypertensive drugs, or antidepressants, as these can influence prolactin levels.

Test Procedure

A prolactin test involves collecting a blood sample. A laboratory technician will clean the patient's arm with an alcohol swab before using a sterile syringe to draw blood from a vein. In infants, blood is usually obtained from the heel.

When taking blood from a vein, the skin is cleansed with antiseptic, and a tourniquet is applied to the upper arm to increase blood flow to the vein. The needle is then inserted into a vein, typically in the inner arm, elbow, or back of the hand, and blood is collected into a vial or syringe. Afterward, the tourniquet is removed, and the puncture site is covered with a bandage to stop any bleeding.

The collected blood sample is then placed in a test tube and analyzed by laboratory staff using specialized equipment. The results of the test may take up to a day, depending on the laboratory's procedures.

Normal and Abnormal Values

General normal prolactin values for adults are as follows:

• Men: Less than 20 ng/mL (nanograms per milliliter)
• Women: Less than 25 ng/mL
• Pregnant or breastfeeding women: 80 to 400 ng/mL

It is important to note that normal prolactin values may vary slightly between laboratories. Abnormal prolactin levels are typically considered higher than the normal range and may indicate underlying health issues.

Results and Recommendations (Follow-up Tests)

Elevated prolactin test results in the blood can lead to various symptoms, including infertility, decreased sexual desire, and milk discharge from the nipples when not pregnant or breastfeeding. Several factors can cause an increase in prolactin levels, such as prolactinoma (a tumor in the pituitary gland, which is one of the most common causes), specific medications, certain health conditions, and other tumors within the pituitary gland.

Prolactinoma primarily affects individuals under 40 years old and is uncommon in children and older adults. Treatment options for prolactinoma typically include medications, but surgical intervention and radiation therapy may also be necessary in certain cases.

Medications that suppress prolactin production often target dopamine pathways, as dopamine naturally inhibits prolactin release. These medications include antipsychotics like risperidone, some antihypertensive drugs, medications for nausea and vomiting, and opioid-containing pain relievers.

Certain health conditions, such as kidney disorders and hypothyroidism, can also disrupt prolactin levels.

Consult the Right Doctor

If your prolactin test results show abnormalities, consult a general practitioner for an accurate diagnosis and tailored therapy. You may also need to see an obstetrician or endocrinologist to receive specialized treatment.

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