RESUMO
Newborns are especially prone to oxidative stress (OS). Many free radical-mediated diseases have been described in newborns including bronchopulmonary dysplasia, respiratory distress syndrome, encephalopathy, and kidney injury. Objective of this work was to determine predictive and diagnostic value of urinary malondialdehyde (UMDA) as a marker for acute kidney injury (AKI) in critically sick full-term newborns. 67 critically sick full-term neonates were enrolled in the study including 31 newborns with AKI (group I) and 36 newborns without AKI (group II). The control group included 40 healthy full-term neonates (group III). The level of UMDA was measured by means of the test based on the reaction of MDA to thiobarbituric acid. The mean and 95% confidence interval (CI) for UMDA was 12.7 (11.5; 13.9) µmol/l in group I, 10.2 (9.61; 10.8) µmol/l in group II, 9.01 (8.16; 9.93) µmol/l in group III (pI-II<0.05; pI-III<0.05; pII-III<0.05). ROC curve analysis showed that UMDA had AUC 0.80 (95% CI 0.68; 0.93, p=0.0014) for AKI. The optimum UMDA cut-point was 12.0µmol/l. For AKI sensitivity and specificity of UMDA were determined to be 68.2% (95% CI 45.1; 86.1%) and 85.7% (95% CI 69.7; 95.1%) respectively, with positive predictive value of 75.0% (95% CI 55.9; 87.6%), and negative predictive value of 81.1% (95% CI 69.7; 88.9%), positive likelihood ratio of 4.77 (95% CI 2.02; 11.3), and negative likelihood ratio of 0.37 (95% CI 0.20; 0.69). This data support studies to evaluate UMDA as an immediate biomarker for AKI in critically sick newborns. However, a larger study should be conducted to assess the diagnostic accuracy of other serum and urinary markers for OS and renal dysfunction, which would enable us to formulate a mathematical model for the prognosis and diagnosis of AKI in newborns.