Drug-induced hyperprolactinaemia

The main drugs which induce hyperprolactinaemia are:

• major tranquilisers - block dopamine binding sites
• metoclopramide - block dopamine binding sites
• tricyclic antidepressants - block catecholamine re-uptake
• reserpine - depletes catecholamines
• methyl-dopa - blocks conversion of tyrosine to dihydroxyphenylalanine and dopamine
• oral contraceptives - promote the synthesis and storage of prolactin
• bendrofluazide, omeprazole, ranitidine, cimetidine and famotidine have occasionally been reported to cause hyperprolactinaemia

Drug-induced increases in serum prolactin do not generally lead to levels above 2500 mU/L; however occasionally levels up to 6000 mU/L have been observed (1).

In cases of suspected drug-induced hyperoprolactinaemia where very high levels of prolactin are seen (over 2500 mU/L) then detailed physical examination (including visual fields), pituitary imaging and measurement of pituitary hormone levels are indicated.

Reference:

• (1) Prescribers' Journal (2000), 40 (2), 157-168.