To establish the numerical prevalence and severity of raised prolactin levels in patients apparently asymptomatic.

All outpatients with schizophrenia receiving antipsychotics at Small Heath Health Centre had routine annual prolactin measurements. the sampling was done 0900-1300 either in clinic or at patient's homes. the Upper Limit of Normal (ULN) for prolactin was set by the hospital pathology service at 324 mIU/L (males) and 496 mIU/L (females). Sampling was done 0900-1200 either in clinic or at patient's homes. We recorded the patient's name, age, unit number, ethnicity, details of current medication, recent changes to medication and symptoms of hyperprolactinaemia.

Prolactin levels were obtained for 43 patients (M: 24 F:19). All of these patients had no clinical symptomatology that had led to prolactin measurements previously. Abnormal values were found in 47 per cent of females and 58 per cent of males, or 56 per cent (n=24) of the whole cohort. the mean prolactin was 789 mIU/L with a mean of 497 mIU/L in males and 1100 mIU/L in females. All patients on oral risperidone had hyperprolactinaemia.

Routine prolactin screening showed abnormal values in 56 per cent of patients and significantly abnormal levels (>1000 mIU/L) that should lead to consideration of drug/dosage alterations in 26% of patients. the prevalence of hyperprolactinaemia in an unselected group of outpatients with schizophrenia suggests that consideration may be given to routine monitoring.