Serum bilirubin levels have been reported to be associated with metabolic syndrome (MS) in the community samples. However, there is no study investigating this issue in schizophrenia patients receiving atypical antipsychotics that their metabolic side effects constitute a serious problem.

We investigated the association between serum bilirubin levels and MS and, its stability.

This is a naturalistic, prospective study.The sample of this study consisted of 138 schizophrenia patients receiving atypical antipsychotics.The patients with the first 50th percentiles of serum direct bilirubin levels (low bilirubin group) were compared to those with the second 50th percentiles (high bilirubin group) in terms of MS criteria based on ATP-III criteria. The patients reevaluted after 6 months.The correlation between serum bilirubin levels and MS parameters were examined.

In high bilirubin group, 75.0% of patients were free of MS itself (p = < .001) or its criteria of triglyceride (73.4%), fasting blood glucose (84.4%), HDL levels (61.4%), and waist circumference (53.1%) criterion compared to low bilirubin group (p < .05). At follow-up, significant group differences were still evident for MS itself and for fasting blood glucose and HDL levels. Direct bilirubin levels were significantly correlated with the triglyseride and HDL levels at the baseline and follow-up (p < .05).

We found that high levels of serum direct bilirubin may be associated with the lower risk for MS in schizophrenia patients. Our results have suggested that serum direct bilirubin levels may be used for predicting to MS risk for schizophrenic patients.