Causes of nipple discharge

Hyperprolactinaemia

Galactorrhoea is usually associated with a raised prolactin level (hyperprolactinaemia).

There is a long list of causes of hyperprolactinaemia, but the key causes to remember are:

• Idiopathic (no cause can be found)
• Prolactinomas (hormone-secreting pituitary tumours)
• Endocrine disorders, particularly hypothyroidism and polycystic ovarian syndrome
• Medications, particularly dopamine antagonists (i.e., antipsychotic medications)

Prolactin suppresses gonadotropin-releasing hormone (GnRH) by the hypothalamus, leading to reduced LH and FSH release. Therefore, hyperprolactinaemia can also present with:

• Menstrual irregularities, particularly amenorrhoea (absent periods)
• Reduced libido (low sex drive)
• Erectile dysfunction (in men)
• Gynaecomastia (in men)

Assessment

• Breast examination - determine whether there is a mass lesion present