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Prolactin

Definition

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

Alternative Names

PRL

How the test is performed

A blood sample is needed. For information on how this is done, see: Venipuncture

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, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

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
  • Impotence
  • Infertility
  • Irregular or no menstrual periods (amenorrhea)

Normal Values

The normal values for prolactin are:

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

The examples above are common measurements for results for these tests. Normal value ranges may vary slightly among different laboratories. Some lab use different measurements or may test different specimens.Talk to your doctor about the meaning of your specific test results.

Note: ng/mL = nanograms per milliliter

What abnormal results mean

People with the following conditions may have high prolactin levels:

  • Chest wall trauma or irritation
  • Hypothalamic disease
  • Hypothyroidism
  • Kidney disease
  • Pituitary tumor that makes prolactin (prolactinoma)
  • Other pituitary tumors and diseases

Certain medications can also raise prolactin levels, including:

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

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

What the risks are

Veins and arteries vary in size from one patient 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)

Special considerations

The following can temporarily increase prolactin levels:

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

References

Melmed S, Kleinberg D. Anterior pituitary. In: Kronenberg HM, Melmed S, Polonsky KS, Larsen PR, eds. . 11th ed. Philadelphia, PA: Saunders Elsevier; 2008:chap 8.

Molitch ME. Anterior pituitary. In: Goldman L, Schafer AI, eds. . 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 231.

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    Encyclopedia content is provided as information only and not intended to replace the advice and instruction from your personal physician.