Prolactin
Lactogenic Hormone
Results
A prolactin test measures the level of the hormone prolactin, which is made by the pituitary gland, in your blood. Prolactin levels are different throughout the day. The highest levels occur during sleep and shortly after you wake up.
Normal
Normal values may vary from lab to lab.
Prolactin Nonpregnant women Less than 25 nanograms per milliliter (ng/mL) or 25 mcg/L (SI units)
Men Less than 20 ng/mL or 20 mcg/L (SI units)
Pregnant women 20 to 400 ng/mL or 20 to 400 mcg/L (SI units)
High values
- High levels of prolactin (usually higher than 200 ng/mL) may mean a pituitary gland tumor (prolactinoma) is present. The higher the prolactin level, the more likely a pituitary gland tumor is present. If a prolactin level is over 200 ng/mL, a magnetic resonance imaging (MRI) test may be done to confirm a pituitary tumor is present. A normal or low prolactin level does not always mean there is no pituitary tumor. An MRI test may be done if a pituitary tumor is suspected.
- High levels of prolactin may mean that the pituitary gland is making excess prolactin for unknown reasons (idiopathic hyperprolactinemia).
- Other conditions that can cause high prolactin levels include pregnancy, liver disease (cirrhosis), kidney disease, and hypothyroidism.
Many conditions can affect prolactin levels. Your health professional will talk with you about any abnormal results in relation to your symptoms and medical history.
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| Author: | Sandy Jocoy, RN | Last Updated: July 15, 2008 |
| Medical Review: | Joy Melnikow, MD, MPH - Family Medicine Deborah A. Penava, BA, MD, FRCSC, MPH - Obstetrics and Gynecology | |
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| Topic Contents | |
| Test Overview | |
| Why It Is Done | |
| How To Prepare | |
| How It Is Done | |
| How It Feels | |
| Risks | |
 | Results |
| What Affects the Test | |
| What To Think About | |
| References | |
| Credits | |