Cannulated prolactin test

About a cannulated prolactin test

This is a blood test to measure your level of prolactin.

Prolactin is a hormone made by your pituitary gland (a small gland at the base of your brain).

Sometimes, prolactin levels can rise due to a stressful situation, such as having a blood test. This means we might not be able to measure your true hormone levels.

A cannulated prolactin test means we use a small tube (cannula) in your arm to take blood samples while you rest. This helps us to get a more accurate result.

Why we offer this test

Your doctor has found that a blood test indicated your prolactin level was higher than normal.

This can be due to stress, a medical condition, or something else.

We use a cannulated prolactin test to help us decide if the high level of prolactin is real, or is just caused by stress.

If it is caused by stress, this can help us avoid giving you unnecessary scans or treatments.

Preparing for your test

Do the following before your test:

• Avoid food and drink for 8 hours before the test.
• Avoid stress. Try to stay calm and avoid heavy exercise or anything that might cause you stress (like rushing to your appointment).
• Medication: tell your doctor about any medication that you take. Some medications, including certain mental health drugs or hormone treatments, can affect prolactin levels. Do not stop any medication unless your doctor tells you to do so.
• Breast stimulation. Avoid activity that might stimulate your chest area (for example tight clothing or physical contact) for 24 hours before the test. Stimulation can raise your prolactin levels.

You can bring a book or something to listen to, but avoid anything too stimulating.

During the test

You can expect the following during the test.

• When you arrive, a nurse will place a small cannula (thin tube) into a vein in your arm. This might feel like a quick pinch. We will not have to use a needle again during the test.
• We will take a first blood sample immediately, through the cannula.
• You will rest quietly for about 1 hour. You can sit or lie down in a comfortable area. We will try to keep things calm and peaceful for you.
• After 1 hour, we will take a second blood sample through the same cannula.
• After another 30 minutes we will take a final sample and then remove the cannula.
• We will give you a small dressing on your arm.

Pain

Most people feel only a brief sting when the cannula goes in. After that, most patients do not feel much discomfort.

If you feel unwell or dizzy at any point, tell the nursing staff immediately.

Risks

This test is safe. Some patients have a small bruise or slight soreness where we placed the cannula in their arm. It is rare to experience bleeding or infection at the wound site.

If you notice redness, swelling, or pain after your appointment, contact your GP or call NHS 111.

Results

If your prolactin level drops to normal during the test, it is likely that the high level you experienced before was due to stress. You may not need more tests.

If your prolactin level stays high, it can mean you have a medical condition, such as a  pituitary problem. Your doctor may suggest you have a scan (for example an MRI) or other tests.