Prolactin Hormone Test

A prolactin (PRL) test measures the level of this peptide hormone in the blood serum. It is primarily secreted by the anterior pituitary gland. Its main function is to stimulate milk production in the breasts after childbirth (lactation). Outside of pregnancy and lactation, its level remains low. Abnormally high levels (hyperprolactinemia) affect the function of the ovaries and testes by inhibiting the secretion of GnRH, FSH, and LH, which can lead to fertility and menstrual cycle disorders.