[Association between serum direct bilirubin with metabolic syndrome and its components based on a longitudinal health check-up study].

Objective: To investigate the association between serum direct bilirubin (DBIL) with metabolic syndrome (MS) and its components.

Methods: A dynamic health check-up cohort study was set up from 2006 to 2011. 5 258 participants who satisfied the two basic rules: 1) being free of MS at the 1(st) health check-up program; 2) having at least two intact health checks were included in this study. With generalized estimating equation (GEE) model, after adjusting for items as age, gender, smoking, drinking, alanine aminotransferase, aspartate aminotransferase, γ-glutamyltransferase, uric acid, blood urea nitrogen and white blood cells, the multivariable relative risks (RRs) of DBIL with MS and their components were analyzed.

Results: The RRs of DBIL for MS was 0.722 (95%CI: 0.654-0.797), which showing a dose-response. Serum DBIL was negatively associated with obesity and hyperlipidemia. Taking factors as gender and age into account, in the <45 years and 45-55 years groups, the RRs of DBIL for MS in females appeared as 0.516 (95%CI: 0.349-0.761) and 0.435 (95%CI: 0.256-0.740). And in males of <45 years and 45-55 years, the RRs of DBIL for MS were 0.738 (95% CI: 0.644-0.846) and 0.790 (95% CI:0.667-0.937), respectively.

Conclusions: The elevated DBIL levels in serum appeared an early biomarker for MS and its components (obesity and hyperlipidemia). In particular,they may play a role in reducing the risk of MS in both females and males before 55 years of age.