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

Blood is drawn from a vein on the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and an elastic band is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the band to fill with blood.

A needle is inserted into the vein, and the blood is collected in an airtight vial or a syringe. During the procedure, the band is removed to restore circulation. After the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In an infant or young child, the area is cleansed with antiseptic and punctured with a sharp needle or lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. A cotton pad or a bandage may be applied to the puncture site, if bleeding does not quickly stop.

No special preparation is necessary.

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.