Prolactin Levels
Reviewed
A prolactin test measures the level of prolactin in your blood. Prolactin is a hormone that mainly signals breast tissue to grow during pregnancy and produce milk for breastfeeding. Levels are normally high in pregnant and breastfeeding women and low in nonpregnant women and men.
Preparation and collection
Your provider will let you know if you need to fast (not eat or drink) for several hours before the test. For accuracy, your blood sample is usually scheduled for three to four hours after you wake up. Tell your provider about any medicines or vitamins you take, as they can affect prolactin levels. Do not stop any medicine without talking to your provider first.
Understanding this test
Use the reference interval and units printed by the laboratory that performed the test. A result outside that interval is not a diagnosis by itself, and a result inside it does not rule out every condition. Your symptoms, history, medicines, timing, and related tests can change what the result means.
- Higher-than-normal levels do not always mean a medical condition needs treatment; small increases can be temporary.
- The test cannot identify the specific cause of abnormal prolactin levels.
- Results must be interpreted alongside symptoms, medical history, and other tests.
What to do next
If your results are abnormal, your provider will discuss further testing and treatment options. For high levels, additional blood tests and possibly an MRI may be ordered. For low levels, your provider will advise on any necessary follow-up.