IL6 and Renal insufficiency: To further dissect potential drivers of lower Myostatin levels in ICU patients, we performed extensive correlation analyses between Myostatin serum levels and clinically established risk scores (e.g., APACHE II and SOFA) as well as a broad variety of laboratory markers indicating different types of organ dysfunction such as renal failure (creatinine), liver failure (bilirubin, AST, GGT) or systemic inflammation (leukocytes, CRP, PCT, IL-6).