Changes of serum bilirubin and uric acid in patients with myasthenia gravis

Objective To explore the correlations of serum total bilirubin (TBIL), direct bilirubin (DBIL), indirect bilirubin (IBIL) and uric acid (UA) with myasthenia gravis (MG). Methods A total of 131 MG patients were selected as MG group and 176 healthy cases as control group.They were enrolled from the Department of Neurology, First Affiliated Hospital, Anhui Medical University between January 2010 and December 2012.And the controls were recruited from a health check-up center.The total serum BIL and UA concentrations were measured by an enzymatic method.All MG patients underwent thymus computed tomography (CT) scanning. Results The serum levels of TBIL, IBIL and UA in patients with MG ((11.0±0.4, 7.4±0.3, 270±70) μmol/L) were significantly lower than those in healthy control group ((13.0±0.4, 9.6±0.3, 301±60) μmol/L)(P<0.01).Moreover, these results were consistent when the male and female cohorts were investigated separately.In MG group, females had significantly lower serum TBIL, IBIL and UA levels ( (10.1±3.7, 6.7±2.7, 242±68) μmol/L) than males ((12.2±5.5,8.4±4.2,288±73) μmol/L)(P<0.05-0.01).However, no difference existed when comparing different grades of MG patients according to the modified Osserman classification.Also no significant difference existed between MG patients with thymic abnormalities and those without.In comparison with the subjects in the reference group (total bilirubin≥11.4μmol/L, UA≥279μmol/L), the odds ratio (95% CI) for MG patients in the lower tertile (total bilirubin<11.4μmol/L, UA<279μmol/L) were 1.98 (1.20-3.29) and 2.22 (1.29-3.82) respectively after multivariable adjustment.Serum level of TBIL and UA had positive correlations with creatintine as indicated by Pearson correlation analysis (r=0.151, P=0.008|r=0.301, P=0.000).Meanwhile,serum level of UA had a negative correlation with high density lipoprotein-cholesterol (r=-0.347, P=0.000). Conclusion Decreased serum levels of BIL and UA are closely correlated with MG.As a replacement therapy, administration of BIL and UA or theirs precursors may offer benefits to the MG patients. Key words: Bilirubin; Uric acid; Mysthenia gravis