Does hyperprolactinaemia cause nipple discharge?

Prolactin is a hormone involved in breast milk production. When its level is raised outside pregnancy or breastfeeding, breast tissue may produce a milky fluid. This is called galactorrhoea and it may affect one or both nipples. Hyperprolactinaemia can also be associated with changes in menstrual periods, reduced fertility, vaginal dryness or lower sexual desire. Some people have no noticeable symptoms besides discharge.

Raised prolactin may be linked with medicines, an underactive thyroid, irritation or stimulation of the nipples, or a problem affecting the pituitary gland. The appearance of the fluid and whether it comes from one duct or several can help guide assessment. Nipple discharge that is bloody, clear and spontaneous needs a clinical review because its causes are not limited to hormone changes.

Arrange an appointment with a doctor or gynaecologist if discharge is new, persistent or unexplained. They may ask about pregnancy, breastfeeding, periods and medicines, examine the breasts, and request a prolactin test or thyroid testing. Prolactin can vary with stress, recent breast stimulation and the timing of a blood test, so follow the testing instructions you are given.

Avoid repeatedly squeezing the nipples to check for fluid, as stimulation can encourage further discharge. Do not stop a prescribed medicine without advice. Keep a note of the colour, whether the fluid appears without touching the breast, and any lump, pain or skin change.

Seek prompt medical assessment for spontaneous discharge from one breast, bloody or clear fluid, a new breast lump, nipple inversion, skin dimpling, redness, warmth or fever. Arrange medical review for discharge with headaches or vision changes, as these can occur when a pituitary condition affects nearby structures. Urgent help is appropriate for severe headache with sudden visual loss or other sudden neurological symptoms.

You could ask: Could my medicines or thyroid function affect prolactin? Should the prolactin test be repeated under particular conditions? Does the discharge need breast imaging or a breast specialist review? Which symptoms should prompt faster care? If hyperprolactinaemia is confirmed, what treatment or follow-up would be suitable for me?