EDP column by Dr Ketan Dhatariya

“My periods have become more irregular recently. My GP did some blood tests and told me my ‘prolactin’ levels were high. What is this?"

Prolactin, as the name suggests is the hormone responsible for promoting lactation – that is breast milk production. It is produced by a few cells in the pituitary gland found at the base of the brain. Prolactin levels usually rise when you are pregnant, in anticipation of breastfeeding, and stay up for the time you continue to breast feed. Prolactin can be thought of as nature’s contraceptive. High prolactin levels suppress the production of the other hormones that are responsible for the normal menstrual cycle. This means that when breastfeeding, ovulation becomes less likely and you are less likely to be able to conceive. This is why your periods may have become irregular.

However, several other things can cause your prolactin to rise when they are not supposed to. If the blood test was taken at a time of stress – such as if the person taking your blood struggled to find a vein, or they had a bit of a ‘dig about’ taking the blood causing some pain, that could cause the prolactin to rise. If this is suspected, it may be worth having the prolactin levels measured again.

There are signals that control the rate of prolactin, and if the part of the brain along which these signals travel are damaged, for whatever reason, then prolactin levels may rise. In addition, particular medications can interfere with these control signals – it may be worth mentioning these to your GP, remembering to include anything that you may buy at the chemist.

The last cause of a raised prolactin is when a few of the cells within the pituitary decide to ignore the control signals. Normally, the control signals stop the production of too much prolactin, but if the cells within the pituitary gland decide to ignore the signals, then prolactin levels rise. The cells within the pituitary may get bigger and cause a small lump (or ‘adenoma’) to appear which can be seen if the pituitary gland is scanned.

The treatment for high prolactin levels depends on the cause. If it is a medication, then ask for a non-prolactin raising alternative, or if it is any of the other causes, it may be necessary to have a medication to suppress the high levels of prolactin.

As always, if you do not understand what your GP has told you, ask them to explain it again in language that you do understand.

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