Hyperprolactinaemia: excess of prolactin and fertility

Hyperprolactinaemia: excess of prolactin and fertility

Prolactin is a hormone that is produced by the   pituitary gland and although it also forms part of the   stress hormone circuit, it plays a vital role in breast development during pregnancy and the production of breast milk after giving birth.

Abnormally high levels of prolactin, which is referred to as hyperprolactinemia, causes disruptions in the normal menstrual cycle, anovulatory cycles, infertility and the   production and spontaneous flow of breast milk in women who are not pregnant or breastfeeding a baby.


  1. Physiological causes: insomnia, stress, too much exercise, excessive breast manipulation.
  2. Diseases: hypothyroidism,  polycystic ovary syndrome  and others.
  3. Some medication, such as that used to stop sickness and nausea.
  4. On rare occasions, pituitary tumours called prolactinoma that can be controlled with medication in the majority of cases.


In general, it causes altered menstruation patterns that range from changes in the normal cycle to missing a period completely and it can be accompanied with the secretion of breast milk.

Other associated symptoms that can be experienced are: headaches, decreased libido, hirsutism  or excessive hairiness especially when it is associated with polycystic ovary syndrome, infertility or  recurrent miscarriages.


If a woman is thought to have abnormally high levels of prolactin, a test to determine the prolactin blood levels will be carried out regardless of the day of the menstrual cycle. This should be done in the morning, while resting, and stressful situations that can raise the levels must be avoided. If the levels are found to be high, this must confirmed with at least one more test.

When a high level of prolactin has been confirmed pregnancy, taking medication that increases prolactin levels, hypothyroidism and/or polycystic ovary syndrome can be ruled out.

After ruling out the possible causes, if the increased level of prolactin is significant and there is still no explanation for this, a pituitary MRI is carried out to determine whether there is a pituitary tumour (adenoma) producing the prolactin.


When there is a known cause for this such as a medication, hypothyroidism… it must be treated to get the prolactin levels back to normal and therefore restore fertility.

In other situations (including the pituitary tumours) the treatment consists in taking oral medication such as Cabergoline that normalizes prolactin levels and therefore restores the    regular menstrual cycles and ovulation, and it also stops the production of breast milk.

If the return of normal menstrual cycles is not enough, the most suitable assisted reproduction technique for each specific case will then be used.

Dr. Pino NavarroEndocrinologist. Head of the Endocrinology and Nutrition Department at the Instituto Bernabeu

Find out about the medical unit “endocrinology and nutrition at Instituto Bernabeu”

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