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 Non-pregnant women Less than 25 micrograms per litre (mcg/L) (SI units) or 25 nanograms per millilitre (ng/mL)
Men Less than 20 mcg/L (SI units) or 20 ng/mL
Pregnant women 20 to 400 mcg/L (SI units) or 20 to 400 ng/mL
High values
- High levels of prolactin (usually higher than 200 mcg/L) may mean a pituitary gland tumour (prolactinoma) is present. The higher the prolactin level, the more likely a pituitary gland tumour is present. If a prolactin level is over 200 mcg/L, a magnetic resonance imaging (MRI) test may be done to confirm a pituitary tumour is present. A normal or low prolactin level does not always mean there is no pituitary tumour. An MRI test may be done if a pituitary tumour 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: | 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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| 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 | |