A prolactin (PRL) test measures the level of prolactin in the blood. Prolactin is a

hormone made by the pituitary gland, a small gland at the base of the brain. Prolactin causes

the breasts to grow and make milk during pregnancy and after birth. Prolactin levels are

normally high for pregnant women and new mothers. Levels are normally low for

nonpregnant women and for men.The normal values for prolactin are: Men: less than 20

ng/mL (425 µg/L) Nonpregnant women: less than 25 ng/mL (25 µg/L) Pregnant women: 80

to 400 ng/mL (80 to 400 µg/L).