Blood test
Prolactin Test
A prolactin test measures the hormone prolactin, made by the pituitary gland. A raised level can affect periods, fertility and, in some cases, cause milk production.
Quick answer
Prolactin Test: what it is and what the results mean
Prolactin is a hormone from the pituitary gland that stimulates breast milk production. A prolactin blood test measures its level, which can be raised for several reasons.
- Why it is done: It is used to investigate irregular or absent periods, fertility problems, unexpected milk production, low libido, or symptoms that might suggest a pituitary problem.
- Understanding results: A mildly raised prolactin can be due to stress, medicines or other causes, while a markedly raised level may prompt further tests, including a pituitary scan, to look for a cause such as a small benign growth.
What it is
Prolactin is a hormone from the pituitary gland that stimulates breast milk production. A prolactin blood test measures its level, which can be raised for several reasons.
Why it is done
It is used to investigate irregular or absent periods, fertility problems, unexpected milk production, low libido, or symptoms that might suggest a pituitary problem.
What to expect
It is a standard blood test from the arm. Because stress and certain activities can raise prolactin, you may be asked to rest beforehand, and a raised result is often rechecked.
Understanding the results
A mildly raised prolactin can be due to stress, medicines or other causes, while a markedly raised level may prompt further tests, including a pituitary scan, to look for a cause such as a small benign growth.
Good to know
Risks and limitations
The blood test is very safe. Prolactin is affected by stress, medicines and other factors, so a raised result is interpreted carefully and usually confirmed before further investigation.
Education and reference only. This explains the test in general terms and is not medical advice. Always follow the specific instructions from the team arranging your test, and discuss your results with your clinician.
Answers
Prolactin Test: frequently asked questions
What causes a high prolactin level?
Causes include stress, certain medicines, an underactive thyroid, pregnancy and, sometimes, a small benign pituitary growth. A raised result is usually rechecked and investigated to find the cause.
Can medicines raise prolactin?
Yes. Several medicines, including some for mental health and nausea, can raise prolactin. Your clinician will consider your medicines when interpreting the result.
Related tests
Other blood test investigations
Sources
Where this is drawn from
- NHS — Tests and treatments
- NICE — diagnostic guidance
- Association for Laboratory Medicine / relevant professional body
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