Elevated Unconjugated Bilirubin in Schizophrenia Compared to Bipolar Affective Disorder.

Objective: The evidence linking schizophrenia and total and unconjugated bilirubin is primarily from retrospective studies. To overcome this limitation, we conducted a prospective study of total and unconjugated bilirubin levels of patients diagnosed with schizophrenia or bipolar affective disorder.

Methods: Serum total and unconjugated bilirubin levels were compared between patients diagnosed with schizophrenia (n = 50) and bipolar affective disorder (n = 43) (ICD-10 criteria) admitted to an inpatient psychiatric unit of a tertiary hospital in India. The study was conducted between October 2013 and July 2015.

Results: The median serum levels (mg/dL) of total and unconjugated bilirubin were significantly higher (P = .027 and P = .004, respectively) among patients with schizophrenia compared to those with bipolar affective disorder. Analysis of covariance revealed that unconjugated bilirubin was significantly higher (P = .029) in patients with schizophrenia compared to those with bipolar affective disorder, even after controlling for the effects of age, sex, and medications.

Conclusions: In this prospective study, serum levels of unconjugated bilirubin were significantly higher in patients with schizophrenia compared to patients with bipolar affective disorder. The findings suggest that serum unconjugated bilirubin could be a potential marker for schizophrenia. However, the results need to be replicated in a larger sample including patients living in the community.