This meta-analysis of 140 studies comprising 12,421 IL-6 measurements in healthy adult donors determined a pooled average IL-6 level of 5.186 pg/mL (95% CI: 4.631, 5.740) with a reference range extending from 0 to 43.5 pg/mL. Age was found to be a contributing factor, with IL-6 increasing by 0.05 pg/mL
