The early predictive value of urine osmolarity in sepsis associated acute kidney injury

Objective To explore the predictive value of urinary osmolality in sepsis associated acute kidney injury (AKI).

Methods A total of 152 patients with sepsis in the Department of Critical Care Medicine, Zhongshan Hospital, Fudan University from January 2021 to December 2022 were prospectively included, and clinical data and laboratory data were collected. All the patients were divided into AKI group (n＝89) and non-AKI group (n＝63). Urine was collected within 24 hours after sepsis onset, and urine osmolality was measured to assess the level of renal medullary perfusion. Receiver operating characteristic (ROC) curve was used to analyze the efficacy of urine osmolality in predicting sepsis associated AKI, which was compared with that of the traditional indexes (baseline creatinine and urine specific gravity).

Results Urinary osmolality in AKI group was lower than that in non-AKI group (352317.56, 383.96 mOsm/kg vs 487468.79, 559.71 mOsm/kg, P < 0.001). ROC curve analysis showed that the predictive value of urine osmolality (AUC＝0.820, sensitivity 71.9%, specificity 66.0%) was higher than that of the baseline creatinine (AUC 0.706, sensitivity 50.0%, specificity 69.7%; P＝0.037) and urine specific gravity (AUC＝0.606, sensitivity 57.4%, specificity 60.3%; P < 0.001).

Conclusion The evaluation of renal perfusion by urine osmolality can effectively predict the occurrence of sepsis associated AKI.