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Prolactin is a hormone which is produced in the pituitary gland and plays a role in reproductive health. Its primary purpose is to stimulate milk production after childbirth, and in pregnant and breastfeeding women prolactin levels can soar.

What might a low result mean?

It is normal for men and women who are not pregnant or breastfeeding to have low levels of prolactin In their blood. Low levels of prolactin in a breastfeeding woman may impact her milk supply.

What might a high result mean?

Men and women who produce too much prolactin are said to have hyperprolactinemia. This can be caused by a cyst on the pituitary gland which causes the pituitary to secrete more prolactin. Both men and women with high prolactin may find that they have a milky discharge from their nipples. High prolactin is associated with hypothyroidism and can be caused by some medications. In women it is also linked with polycystic ovaries. Because prolactin inhibits ovulation (which is why breastfeeding can act as a natural contraceptive), women with high prolactin levels may have fertility problems.

High prolactin in men can suppress testosterone and cause loss of libido and erectile dysfunction.