Alternative names 

This is a blood test that measures the amount of the hormone prolactin.

How the test is performed
Adult or child:
Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet (an elastic band) or blood pressure cuff is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the tourniquet to distend (fill with blood). A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the tourniquet is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

Infant or young child:
The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.

How to prepare for the test
No special preparation is necessary.

Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child’s age, interests, previous experiences, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child’s age:

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

Serum prolactin is usually measured as part of the diagnostic work-up of Pituitary tumors, menstrual irregularities, infertility, impotence, and Galactorrhea (breast milk production).

Prolactin is a protein hormone secreted from the anterior pituitary gland. Prolactin stimulates breast development and milk production in females. There is no known normal function of prolactin in males.

Normal Values

The normal values for prolactin are as follows:

  • Males and nonpregnant females: 0 to 20 ng/ml  
  • Pregnancy: 10 to 300 ng/ml

Note: ng/ml = nanograms per milliliter

What abnormal results mean

Prolactin levels can be elevated in the following conditions:

  • Prolactinomas  
  • Other Pituitary tumors and disease  
  • Hypothalamic disease  
  • Hypothyroidism  
  • kidney disease  
  • Chest wall trauma or irritation  
  • Medication-related (estrogens, tricyclic antidepressants, metoclopramide, phenothiazines, butyrophenones, reserpine, methyldopa, H2 blockers)

If your prolactin levels are elevated, the test may be repeated following an 8-hour fast.

What the risks are

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

Special considerations

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. stress, recent exercise, and a recent breast examination can transiently increase prolactin levels.

Johns Hopkins patient information

Last revised: December 4, 2012
by Amalia K. Gagarina, M.S., R.D.

Medical Encyclopedia

  A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | 0-9

All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.