Recent studies have suggested an association between elevated levels of bilirubin and psychotic spectrum disorders. The aim of our study was to compare the levels of bilirubin in the different psychotic disorders among themselves and with other mental disorders.

Observational, retrospective, in a sample of patients admitted to the Acute Psychiatric Unit between January 2007 and December 2009. We included all patients with plasma concentrations of bilirubin in the blood analysis. We excluded patients with toxic abuse and alterations in the liver reflected in increased transaminases.

The final sample of 523 patients. Patients with psychotic disorder had bilirubin levels significantly higher than patients with other diagnosis (p < 001).

Psychotic disorders were subdivided into 5 groups: schizophrenia (N = 76), schizoaffective disorder (N = 53), delusional disorder (N = 21), brief psychotic disorder (N = 29) and other unspecified psychotic disorders (N = 34). The brief psychotic disorder patients had bilirubin levels significantly higher than other categories of the same spectrum (p < 0.001).

The psychotic spectrum patients have higher bilirubin levels at admission than other diagnostic entities, and this increase is mainly explained by Brief Psychotic Disorder. Bilirubin figures correlate negatively with psychotic symptoms days, so the brief psychotic disorder, is proclaimed as an ideal model for the llaboratory studies about psychotic spectrum disorders.