Prolactin (Milk Hormone) Test - Prolactin Test

This laboratory test measures the concentration of prolactin (the milk hormone) in the blood serum. This protein hormone is primarily secreted by the mammary cells in the anterior pituitary gland. Its main function is to stimulate milk production after childbirth (lactation). It naturally rises during pregnancy and lactation. Outside of these periods, elevated prolactin levels (hyperprolactinemia) indicate a medical condition that may affect fertility and the menstrual cycle, and may be a sign of a benign pituitary tumor (prolactinium).