Prolactin

Prolactin is a hormone produced by the pituitary gland that primarily stimulates breast milk production, but in elevated amounts can suppress reproductive function and ovulation. Mildly elevated prolactin levels occur in some women with PCOS and can contribute to irregular periods and anovulation, but because significant hyperprolactinemia (high prolactin) can also be caused by pituitary tumors or certain medications that mimic PCOS symptoms, checking prolactin levels is an important step in the diagnostic process to rule out these alternative causes before confirming a PCOS diagnosis.