What is prolactin?

Prolactin on your report

It shows as serum prolactin on a hormone panel.

• Labs set their own normal ranges, so compare your number with the range on your report.
• Ask your doctor whether a repeat test is worth doing if stress or timing may have pushed it up.

What prolactin tells your doctor

Outside pregnancy and breastfeeding, prolactin should stay low.

When it runs high, it can upset the ovaries and cause:

• irregular or missed periods
• difficulty getting pregnant
• sometimes a milky discharge from the nipples

Because irregular periods are also a PCOS sign, your doctor may check prolactin to rule this out.

The most common cause of a high level is a small, non-cancerous pituitary growth called a prolactinoma, while an underactive thyroid, kidney disease and some medicines can also raise it.

What moves your prolactin

Everyday things can nudge prolactin up a little:

• stress
• exercise
• a very high-protein meal
• sexual activity

That's why the sample is usually taken three to four hours after you wake up, and your doctor may ask you to fast beforehand.

To get a fair reading:

• Tell your doctor about every medicine and vitamin you use, since some raise prolactin, but don't stop any on your own.
• Have a calm morning before the test and good sleep.