Prolactin

Lactogenic Hormone

Test Overview

A prolactin test measures the level of the hormone prolactin, which is made by the pituitary gland, in your blood. See an illustration of the pituitary gland.

Pregnant women have high levels of prolactin, which helps make breast milk. During pregnancy, prolactin levels increase by 10 to 20 times. After the baby is born, prolactin stays high if you are breast-feeding. In women who do not breast-feed, prolactin levels return to normal soon after they give birth. After months of breast-feeding, prolactin levels may also return to normal levels even if you still breast-feed.

The pituitary glands of men and non-pregnant women also make prolactin but it is not clear what it does in the body for these people.

Prolactin levels are different throughout the day. The highest levels occur during sleep and shortly after you wake up. Prolactin levels also get higher during times of physical or emotional stress.

Many medicines can cause prolactin levels to go up. Tumours of the pituitary gland can sometimes cause prolactin to be made. A damaged pituitary gland may not be able to make normal amounts of prolactin so levels will be lower.

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Author:	Carrie Henley Jan Nissl, RN, BS	Last Updated: September 26, 2006
Medical Review:	Renée M. Crichlow, MD - Family Medicine Tom Bailey, MD - Family Medicine Kirtly Jones, MD - Obstetrics and Gynecology
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