AIM: To investigate the biliary biochemical constituents and cytokines in infantile hepatitis syndrome (IHS). METHODS: From 42 IHS subjects and 21 controls, serum and biliary biochemical constituents, including total bilirubin (TBIL), direct bilirubin (DBIL), alanine aminotransferase (ALT), gamma-glutamyl transpeptidase (gamma-GT), total bile acid (TBA), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) both in bile and serum, were assayed. The subjects with IHS were divided into a cholestasis group (n = 21) and a hepatitis group (n = 21). RESULTS: In the cholestasis group, serum TBIL, DBIL, ALT, gamma-GT, TBA, IL-6 and TNF-a levels were higher than those in the control (P < 0.01); and also the biliary TBIL, DBIL, gamma-GT and TBA levels were lower than those in the control, whereas biliary IL-6 and TNF-alpha levels were higher than those in the control (P < 0.01). In the cholestasis group, serum IL-6 and TNF-alpha levels were lower than those in bile (P < 0.01). In the hepatitis group, serum DBIL, ALT, gamma-GT, TBA, IL-6 and TNF-alpha levels were higher than those in the control (P < 0.01 or 140.57 +/- 70.32 vs 79.06 +/- 35.25, P < 0.05), while biliary TBIL, DBIL, 7-GT and TBA levels were lower than those in the control (P < 0.01), and biliary IL-6 and TNF-gamma levels were higher than those in the control (P < 0.01). In the hepatitis group, serum IL-6 and TNF-alpha levels were also lower than those in bile (P < 0.01). Serum TBIL, DBIL, gamma-GT, IL-6 and TNF-alpha levels in the cholestasis group were higher than those in the hepatitis group, while biliary IL-6 and TNF-alpha levels in the cholestasis group were higher than those in the hepatitis group. Biliary IL-6 and TNF-alpha were found to be more significantly increased than serum IL-6 and TNF-alpha in IHS (P < 0.01). The biliary IL-6 and TNF-alpha levels were positively correlated with serum DBIL, TBA and gamma-GT levels in IHS subjects. CONCLUSION: Biliary biochemical constituents alter in coincidence with pathological changes in hepatocellular injury. Cholestasis is more serious in IHS patients of cholestasis subtype. Assay of biliary IL-6 and TNF-alpha levels can be specific and sensitive to determine the inflammatory status of impaired liver in IHS. (c) 2006 The WJG Press. All rights reserved.