Hyperprolactinaemia is physiologically normal during pregnancy and lactation. Outside these states, the commonest non-drug causes of hyperprolactinaemia are stress, microprolactinomas, polycystic ovary syndrome and primary hypothyroidism. Women present with infertility, galactorrhoea or menstrual irregularities and unusually with the mass effect of tumour spreading outside the pituitary fossa. Whereas men tend to present later with the effects of larger tumours, such as sexual dysfunction or the space-occupying effect of the pituitary tumours.
The normal pattern of prolactin in pregnancy is for a gradual rise during the first two trimesters followed by a brisk rise in the third trimester to 6000-10,000 mU/L. Prolactin remains elevated during lactation but gradually falls to normal with prolonged breasts feeding.
Drugs causing hyperprolactinaemia
- Dopamine receptor agonists
- Neuroleptics (19% of schizophrenics on neuroleptic agents have galactorrhoea
- Anti-emetics: metoclopramide, domperidone
- SSRI (selective serotonin reuptake inhibitors)
- Tricyclic antidepressants (rare)
- Cardiovascular drugs: verapamil, reserpine, methyldopa
- Highdose oestrogens
- Miscallaneous: bezafibrate, omeprazole, trimethoprim, histamine H2 antagonists