Kidney injury molecule-1/creatinine as a urinary biomarker of acute kidney injury in critically ill neonates

Introduction Acute kidney injury (AKI) is a complex disorder, means acute deterioration of renal function generally occurring over hours to days. Serum creatinine (SCr) is a suboptimal biomarker in neonates as the creatinine concentration reflects the maternal level for up to 72 h after birth, to improve the ability for early prediction of AKI and improve clinical outcomes, there has been a significant amount of research to identify novel biomarkers of damage to allow for the earlier identification of neonates with AKI. Objective This study aimed to study the effectiveness of urinary kidney injury molecule-1/creatinine (uKIM-1/cr) in the diagnosis of AKI in critically ill neonates. Study design The patients' group included 50 critically ill full-term septic neonates (39 of them developed AKI according to guidelines of AKI diagnosis), and control group including 50 healthy neonates. Full history taking, clinical assessment and laboratory testing of the renal functions (urea & creatinine), eGFR, uKIM-1 by ELISA technique and uKIM-1/cr ratio on admission, and on day 3 of admission. Results Urea, serum creatinine increased, whereas, eGFR decreased significantly in the second sample when compared to the first sample of the AKI group. uKIM-1 and uKIM-1/cr were high in the first sample, uKIM-1 concentration and uKIM-1/creatinine were higher in second sample (2.2 +/- 0.6 ng/ml & 7.1 +/- 2.1 ng/mg) when compared to first sample (0.6 +/- 0.1 ng/ml & 2.6 +/- 0.9 ng/mg) in critically ill neonates with AKI. Serum creatinine, uKIM-1 and uKIM-1/cr ratio were significantly associated with higher KDIGO stages. Applying the ROC curve at the first sample for discrimination between critically ill neonatal patients with and without AKI, uKIM-1/cr AUC was significantly higher when compared to AUCs of creatinine, eGFR, uKIM-1. Regression analysis revealed that high uKIM-1 & uKIM-1/cr are independent predictors for AKI within critically ill neonates. So, uKIM-1 & uKIM-1/cr are early biomarkers as their level increased before creatinine increases. Conclusions uKIM-1 and uKIM-1/cr are good early indicators for AKI in neonates suffering from a critical illness.