Kaddourah A, et al. - In this post hoc analysis of a prospective international observational multicenter study (Assessment of Worldwide Acute Kidney Injury, Renal Angina, and Epidemiology study), researchers assessed creatinine and urine output criteria for acute kidney injury, individually and collectively, to determine their differential influence on the diagnosis and outcome of severe acute kidney injury. No increase in serum creatinine was detected in approximately one in five critically ill children with acute kidney injury. Comparably poor outcomes were noted in relation to acute kidney injury events only detected by urine output criteria, as compared with those diagnosed by changes in creatinine. Compared with children meeting only one criterion, worse outcomes were seen among those who met both criteria. Among children who develop acute kidney injury, oliguria confers risk for poorer outcomes. A more comprehensive epidemiologic evaluation of acute kidney injury, as well as detection of a subset of children with acute kidney injury who are at higher risk for morbidity and mortality, is possible by applying both the creatinine and urine output criteria.