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Prolactin blood test

Prolactin is a hormone released by the pituitary gland. The prolactin test measures the amount of prolactin in the blood.

How the Test is Performed

How to Prepare for the Test

No special preparation is necessary.

How the Test will Feel

When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.

Why the Test is Performed

Prolactin is a hormone released by the pituitary gland. that stimulates breast development and milk production in women. There is no known normal function for prolactin in men.

Prolactin is usually measured when checking for pituitary tumors and the cause of:

  • Breast milk production that is not related to childbirth (galactorrhea)
  • Decreased sex drive (libido) in men and women
  • Erection problems in men
  • Not able to get pregnant. (infertility)
  • Irregular or no menstrual periods (amenorrhea)

Normal Results

The normal values for prolactin are:

  • Males: 2 to 18 ng/mL
  • Nonpregnant females: 2 to 29 ng/mL
  • Pregnant women: 10 to 209 ng/mL

Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your doctor about the meaning of your specific test results.

What Abnormal Results Mean

People with the following conditions may have high prolactin levels:

  • Chest wall injury or irritation
  • Disease of an area of the brain called the hypothalamus
  • Thyroid gland does not make enough thyroid hormone (hypothyroidism)
  • Kidney disease
  • Pituitary tumor that makes prolactin (prolactinoma)
  • Other pituitary tumors and diseases in the area of the pituitary

Certain medicines can also raise prolactin levels, including:

  • Antidepressants
  • Butyrophenones
  • Estrogens
  • H2 blockers
  • Methyldopa
  • Metoclopramide
  • Phenothiazines
  • Reserpine
  • Risperidone
  • Verapamil

If your prolactin level is high, the test may be repeated in the early morning after an 8-hour fast.

The following can temporarily increase prolactin levels:

  • Emotional or physical stress (occasionally)
  • High-protein meals
  • Intense breast stimulation
  • Recent breast exam
  • Recent exercise


Veins and arteries vary in size from one person to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight but may include:

  • Excessive bleeding
  • Fainting or feeling light-headed
  • Hematoma (blood accumulating under the skin)
  • Infection (a slight risk any time the skin is broken)

Alternative Names



Guber HA, Faraq AF. Evaluation of endocrine function. In: McPherson RA, Pincus MR, eds.Henry's Clinical Diagnosis and Management by Laboratory Methods

Melmed S, Kleinberg D, Ho K. Pituitary physiology and diagnostic evaluation. In: Melmed S, Polonsky KS, Larsen PR, Kronenberg HM, eds.Williams Textbook of Endocrinology

Update Date 10/25/2014