Could urea-to-creatinine ratio become a biomarker of catabolism and response to therapy in major burn patients? A retrospective study

BACKGROUND AND AIMS: Severe thermal burn injuries trigger intense inflammation, hypermetabolism and protein catabolism, and muscle wasting. High protein intakes and pharmacological modulation of hypermetabolism belong to routine therapy in burn centers. The urea-to-creatinine ratio (UCR) has emerged as a potential biomarker of protein catabolism in critical illness. The study aims at assessing the relevance of the UCR in major burns while observing its response to pharmacomodulation with propranolol. METHODS: Retrospective study including burn patients admitted to the intensive care unit (ICU) for burns involving ≥20% of TBSA (total body surface area), surviving >10 days between January 2006 and December 2023. Burn severity was categorized into three groups: 1) 20-40%, 2) 41-60% and 3) >60% TBSA. Standard variables and nutritional management were recorded. Serum C-reactive protein (CRP), urea, creatinine and UCR were compared across the burn groups during the first 30 days, as was use of propranolol. Results as median with interquartile range. RESULTS: Altogether 150 patients were included, aged 46 [29.5, 61.0] years, burned 31.5 [25.0, 54.5]% TBSA. ICU mortality was 12% (18/150). Protein intakes were progressed to 1.4 g/kg/day in Groups 1 and 2, and (1.6 g/kg/day in Group 3). The UCR increased until day 10 reaching a value of 150, initially parallelling CRP, but remained persistently elevated while CRP declined after day 10, with non-significant differences between groups. The urea and UCR values were higher with higher protein intakes (p = 0.001). In the cohort, 85 (56.6%) received propranolol started on day 8. The UCR trajectories were modestly lower with propranolol versus without. CONCLUSION: The urea-to-creatinine ratio is an available and clinically applicable biomarker of catabolism and protein metabolism in major burn patients with persistent high values. Its modest response to propranolol therapy, and association with protein dose suggests it could serve as a potential marker in future interventional studies. Prospective studies are needed to validate its clinical applicability.