Proteinuria as a biomarker of acute kidney injury in severe burn patients

Introduction: Proteinuria in burn patients is common, and it could be associated with acute kidney injury (AKI) with bad outcomes. We evaluated the incidences, outcomes, characteristics and determinants of proteinuria as a biomarker and its influence on AKI and outcomes in burn patients. Methods: This retrospective study was carried out on a group of patients with burn injuries admitted though Emergency Department to burn unit of Hamad General Hospital during a five-year period. Positive urine analysis (R/M) readings were defined as mild ( ±  or 1+) or heavy ( ≥  2+) proteinuria, and AKI was diagnosed and staged according to the Risk, Injury, Failure, Loss, End Stage (RIFLE) classification system. Patient characteristics, management and outcomes were evaluated as well for associations with proteinuria. Results: Of the selected admitted patients to the burn unit during the study period (n = 249), 86 (34.5%) were classified as having proteinuria. In the patients whose total burn surface areas (TBSA) were > 30% (n = 50), 37 patients (74%) had proteinuria and 27 of these patients (72.9%) met AKI criteria. No patients without proteinuria developed AKI. Intensive care unit (ICU) mortality rates were 1%, 16 % and 30% (P <  0.001) in the groups with no, mild and heavy proteinuria, respectively. Conclusions: We observed a high prevalence of proteinuria in patients with severe burns (>30% TBSA). Severely burned patients with proteinuria had a high risk of developing AKI and a poor prognosis for survival. This suggests that proteinuria should be used as a biomarker for identifying burn patients at risk of developing AKI.