Serum Endotoxin Activity Measured with Endotoxin Activity Assay Is Associated with Serum Interleukin-6 Levels in Patients on Chronic Hemodialysis

Background: This study aims to evaluate, in patients on chronic hemodialysis (PHD), the levels of endotoxin through a chemiluminescent bioassay based on the oxidative burst reaction of activated neutrophils to complement coated LPS-IgM immune complexes and define the variables possibly correlated. Methods: In 61 PHD, we measured serum endotoxin activity (EA) with the Endotoxin Activity Assay (EAA™) and we defined the possible association with demographic, clinical and laboratory variables. Results: Mean serum EA was 0.43 ± 0.26 UI. EA was low (<0.40) in 29 patients (47.5%), intermediate (0.40-0.60) in 14 (23%) and high (>0.60) in 18 (29.5%). A significant exponential relationship was detected between EA and serum interleukin-6 (IL-6) levels (r = 0.871). At the multiple regression analysis, intermediate-high EA was directly associated only with serum IL-6 levels. In a second model of multiple regression analysis without the variable serum IL-6 levels, intermediate-high EA was directly associated with constipation and serum troponin levels and inversely associated with serum albumin and the monthly number of sevelamer tablets. Conclusions: A high percentage of PHD has intermediate or high EA. Intermediate-high EA is significantly associated with serum IL-6 levels.