In our study, the GFR was estimated by measured creatinine clearance on a 24-hour urine collection. However, the gold standard for GFR assessment is the measure of inuline clearance [25] but the cost and complexity of this tool limits its application in routine. Another limitation is the lack nearly of consensus regarding the upper limit of normal GFR. However, increasing data support the concept of increased GFR in PT patients, and several reports demonstrated subtherapeutic concentrations of drugs in PT patients [5,26]. Also, a cross-sectional single 24-hr measure of CLCR at 10 days in relatively stable patients was performed but fast modifications of kidney function may occur and there is a need for a continuous re-evaluation. Finally, some other factors may influence our results.

In particular, fluid status, cardiac output may be significantly altered from baseline. However, whatever the causes of these alterations, the ATLS (Advanced Trauma Life support) principles are applied in our institution regarding resuscitation of PT patients. We, therefore, believe that the current results are broadly representative of the population of PT patients. It could be argued that the external validity of this single-center study may be limited. However, our findings may be relevant to the vast majority of level I trauma centers, provided that ATLS principles are applied in these institutions.ConclusionsIn hemodynamic ICU stable patients with steady state serum creatinine concentration, CLCR, which is a surrogate marker of GFR, is higher in polytrauma patients than in other critically ill patients.

In ICU patients, the drug monitoring must take into account the glomerular filtration rate. The measure of CLCR should be routinely proposed for PT patients in order to adjust dose regimen, especially for drugs with renal elimination (betalactams, ceftazidime, cefepime, piperacillin, vancomycin, aminoglycosides, and so on).Key messages? In ICU patients with normal serum creatinine, CLCR, is higher in trauma than in non-trauma patients.? The measure of CLCR should be proposed in routine for ICU patients in order to adjust dose regimen, especially for drugs with renal elimination.? Age and trauma were the only factors independently correlated to CLCR.? Glomerular filtration rate should be measured in ICU patient to detect renal filtration abnormalities.

? Serum creatinine is not a good marker for renal function estimation.AbbreviationsAKI: Acute Kidney Injury; CLCR: creatinine clearance; GFR: glomerular filtration rate; ICU: intensive care unit; NPT: non polytrauma patients; PT: polytrauma patients; Carfilzomib sMDRD, Modification of Diet in Renal Disease index; SOFA: score, Sequential Organ Failure Assessment score.Competing interestsThe authors declare that they have no competing interests.Authors’ contributionsAJ and IT carried out the serum creatinine measurement and calibration. SR, AB and TS carried out the patients’ inclusions.