Health Encyclopedia

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

Blood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.

Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.

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 of 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)
Impotence
Infertility
Irregular menstrual periods

Normal Values

The normal values for prolactin are as follows:

Males: 2 - 18 ng/mL
Non-pregnant females: 2 - 29 ng/mL
Pregnant women: 10 - 209 ng/mL

Normal value ranges may vary slightly among different laboratories. 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

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:

Recent breast exam
Recent exercise
Stress

References

Melmed S, Kleinberg D. Anterior Pituitary. In: Kronenberg HM, Melmed S, Polonsky KS, Larsen PR. Kronenberg: Williams Textbook of Endocrinology. 11th ed. Philadelphia, PA: Saunders Elsevier; 2008:chap 8.

Review Date:3/18/2008
Reviewed By:Elizabeth H. Holt, MD, PhD, Assistant Professor of Medicine, Section of Endocrinology and Metabolism, Yale University. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

ADAM Quality A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is the first of its kind, requiring compliance with 53 standards of quality and accountability, verified by independent audit. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial process. A.D.A.M. is also a founding member of Hi-Ethics (www.hiethics.com) and subscribes to the principles of the Health on the Net Foundation (www.hon.ch).

The Agency for Health Care Administration (Agency) and this website do not claim the information on, or referred to by, this site is error free. This site may include links to websites of other government agencies or private groups. Our Agency and this website do not control such sites and are not responsible for their content. Reference to or links to any other group, product, service, or information does not mean our Agency or this website approves of that group, product, service, or information.

Additionally, while health information provided through this website may be a valuable resource for the public, it is not designed to offer medical advice. Talk with your doctor about medical care questions you may have.