SERUM PROLACTIN CONCENTRATION IN PATIENTS TAKING NEUROLEPTIC DRUGS

OBJECTIVE Non-tumour causes of hyperprolactinaemia, including prolacti n-elevating drugs, must be excluded. There is a general view that such drugs are unlikely to raise serum PRL above 3000 mU/l, but the litera ture is confusing. We report 8 patients receiving treatment with neuro leptic drugs, whose serum PRL concentrations were grossly elevated. ME THODS Prolactin was measured using a 2-site immunofluorometric assay ( Abbott Laboratories; reference range < 500 mU/l). Seven of the eight w omen (age range 24-49 years) were symptomatic (galactorrhoea, oligo- o r amenorrhoea). RESULTS Prolactin concentrations ranged from 3600 mU/l to 7300 mU/l. All patients had a normal pituitary CT scan. Five patie nts were treated with bromocriptine without detriment to their mental state. CONCLUSION Prolactin can rise to concentrations associated with prolactinomas in patients on neuroleptic drugs. As it is rarely possi ble to stop the drugs to see if the PRL concentration will decline to normal, neuroradiology is required in these patients to exclude a visi on-threatening macroprolactinoma before deciding on medical treatment.