Serum prolactin concentration in patients taking neuroleptic drugs.

OBJECTIVE

Non-tumour causes of hyperprolactinaemia, including prolactin-elevating drugs, must be excluded. There is a general view that such drugs are unlikely to raise serum PRL above 3000 mU/I, but the literature is confusing. We report 8 patients receiving treatment with neuroleptic drugs, whose serum PRL concentrations were grossly elevated.

METHODS

Prolactin was measured using a 2-site immunofluorometric assay (Abbott Laboratories; reference range < 500 mU/l). Seven of the eight women (age range 24-49 years) were symptomatic (galactorrhoea, oligo- or amenorrhoea).

RESULTS

Prolactin concentrations ranged from 3600 mU/l to 7300 mU/l. All patients had a normal pituitary CT scan. Five patients 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 possible to stop the drugs to see if the PRL concentration will decline to normal, neuroradiology is required in these patients to exclude a vision-threatening macroprolactinoma before deciding on medical treatment.