Low blood selenium concentrations in schizophrenic patients on clozapine

Abstract:

AIMS: To compare plasma and red-cell selenium concentrations of schizophrenic patients treated with clozapine, with healthy controls and patients with mood disorders.

METHODS: Plasma and red-cell selenium concentrations were measured in random venous blood samples from four groups: mood disorder (n = 36), schizophrenics treated with clozapine (n = 54), schizophrenics not treated with clozapine (n = 41) and a healthy control group (n = 56). Assays were performed by an independent laboratory that was blinded to the patient groups and specializes in estimating trace metal concentrations.

RESULTS: Selenium concentrations in plasma and red cells were found to be significantly lower in schizophrenic patients treated with clozapine as compared with all other groups.

CONCLUSIONS: Selenium is an essential antioxidant. Its deficiency has been implicated in myocarditis and cardiomyopathy. Low selenium concentrations in clozapine-treated patients may be important in the pathogenesis of life threatening cardiac side-effects associated with clozapine. Further clinical studies are being conducted to explore this important clinical observation and its therapeutic implications.

Selenium deficiency has long been implicated in both myocarditis(inflammation of the heart muscle) and cardiomyopathy (other forms of heart disease). These are among the life-threatening cardiac side-effects associated with the atypical neuroleptic clozapine. 

In this careful case-control study, blood selenium concentrations were found to be significantly lower in schizophrenia patients treated with clozapine when compared with schizophrenia patients receiving other medications, patients with mood disorder, or healthy controls.

Low selenium status might therefore help to explain the elevated risk of cardiac deaths in clozapine-treated patients, although this still requires investigation via randomised controlled trials.