Graduate School, Tianjin Medical University Graduate School, Tianjin University of Traditional Chinese Medicine Tianjin Liver Disease Institute, Tianjin Infectious Disease Hospital, Tianjin, China.
Aim: Previous studies have shown significantly elevated levels of interleukin (IL)-6 in cirrhotic patients with minimal hepatic encephalopathy (MHE), but the relationship between circulating levels of IL-6 and ammonia is unclear. The aim of this study is to investigate the relationship between both variables in cirrhotic patients with MHE. Methods: Psychometric tests including number connection test part A (NCT-A) and digit symbol test (DST) were performed to diagnose MHE in 85 cirrhotic patients. Simultaneously, circulating levels of IL-6 and ammonia were measured. Results: Thirty-two (37.6%) cirrhotic patients were diagnosed with MHE. IL-6 and ammonia were the independent predictors of the presence of MHE (P < 0.05 for both variables). Circulating levels of IL-6 and ammonia correlated with the severity of MHE represented by results of NCT-A (r = 0.56, P < 0.05 and r = 0.39, P < 0.05, respectively) and DST (r = -0.48, P < 0.05 and r = -0.47, P < 0.05, respectively). Moreover, there was a significant correlation between circulating levels of IL-6 and those of ammonia in patients with MHE (r = 0.61, P < 0.05), and a positive additive interaction was found between IL-6 and ammonia on the presence of MHE, with a significant synergy index of 1.51 (95% confidence interval = 1.12-3.46). Conclusion: The present study demonstrates a significant correlation and a positive additive interaction between IL-6 and ammonia in cirrhotic patients with MHE, suggesting that IL-6 may have a potential synergistic relationship with ammonia in the induction of MHE.