Serum bilirubin concentrations and multiple sclerosis

Bilirubin is the end product of heme catabolism by heme oxygenases. Although bilirubin has long been considered as a toxic waste product, it is now recognized as an endogenous antioxidant. It has been reported that bilirubin is an effective treatment in both acute and chronic experimental autoimmune encephalomyelitis (EAE) disease models. However, the relationship between bilirubin and multiple sclerosis (MS) has not been fully explored. The serum bilirubin concentrations were measured in 340 individuals comprising 88 healthy subjects, 133 patients with MS and 119 patients with cerebral infarction. Serum total bilirubin (Tbil), direct bilirubin (Dbil) and indirect bilirubin (Ibil) concentrations were significantly lower in patients with MS than in either patients with cerebral infarction or healthy controls (p < 0.001). The correlation identified between bilirubin and MS was still highly significant when the effect of gender was eliminated. Among patients with MS, Tbil, Dbil and Ibil concentrations were lower in patients with MS with longer duration (>2 years), less disabling disease (Expanded Disability Status Scale score < 3), and inactive MRI appearance, although the differences did not reach statistical significance. Our results suggest that there are reduced serum bilirubin concentrations in patients with MS.