Haines RW, et al. - Whether elevated urea:creatinine ratio would offer a biochemical signature of muscle catabolism and characterise prolonged ICU admissions following major trauma, was investigated by analyzing two existing data sets of adults surviving ≥ 10 days after admission to ICU post-major trauma. This study included overall 1,173 patients. Researchers noted that reduction in L₄ psoas and L₃ muscle cross-sectional areas between computerised tomography (CTs) significantly correlated with time elapsed in 107 patients undergoing serial CTs. A significantly greater rate of muscle reduction was detected in 53/107 patients with the second CT during evolving, current or recent persistent critical illness. Overall, skeletal muscle wasting was accompanied by elevated urea:creatinine ratio and therefore, elevated urea:creatinine ratio was viewed as a biochemical signature of persistent critical illness following major trauma. Urea:creatinine ratio, if prospectively validated, affords a potential proxy of catabolism to study in epidemiological and interventional investigations.