Serum-Creatinine-Estimated Augmented Renal Clearance is Associated with Marked Weight Loss after Severe Traumatic...

Augmented renal clearance is commonly evaluated as a pharmacokinetic problem in critically ill trauma patients. In severe traumatic brain injury (TBI), increased serum-creatinine-estimated creatinine clearance may also reflect a broader hyperdynamic or metabolically vulnerable phenotype. We aimed to characterize the incidence and clinical profile of serum-creatinine-estimated augmented renal clearance (eARC) after severe TBI and to examine its association with day-28 body weight loss.

We performed a retrospective observational cohort study of intensive care unit (ICU) admissions of adults with severe traumatic brain injury (TBI) at a tertiary academic level I trauma center between 2015 and 2024. Because measured urinary creatinine clearance was not systematically available, serum-creatinine-estimated augmented renal clearance (eARC) was defined as estimated creatinine clearance (eCrCl) ≥ 130 mL/min/1.73 m² at one or more available eCrCl time points during the first 28 days after injury. Covariate selection was guided by a directed acyclic graph. Additional sensitivity analyses incorporated propofol-derived calories, sodium variables, fluid input, urine output, and the input-minus-urine fluid balance estimate.

Among 342 included admissions, eARC occurred in 197 patients (57.6%). Patients with eARC were younger, more often male, and had lower admission Glasgow Coma Scale (GCS) scores. Patients with eARC experienced greater day-28 body weight loss than non-eARC patients (median -12.7% vs. 0.0%; p < 0.001), and severe weight loss was more frequent in the eARC group. In exploratory multivariable analysis adjusted for age and admission GCS score, eARC remained associated with severe day-28 weight loss. After incorporating propofol-derived calories, total energy delivery was similar between eARC and non-eARC groups. Serum sodium, fluid input, urine output, and the input-minus-urine fluid balance estimate did not show clear group-level differences that explained the observed weight-loss difference.

Serum-creatinine-estimated augmented renal clearance (ARC) was common after severe TBI and was associated with marked day-28 weight loss. These findings are hypothesis generating and suggest that eARC may identify a metabolically vulnerable subgroup, but prospective studies using measured creatinine clearance, detailed sodium-water balance assessment, and direct body composition measures are needed.