Urinary Albumin Levels Predict Development of Acute Kidney Injury after Pediatric Cardiac Surgery: A Prospective Observational Study

Objective Mortality and morbidity of acute kidney injury (AKI) after cardiac surgery still remain high. The authors undertook the present study to evaluate the utility of early postoperative urinary albumin (uAlb) as a diagnostic marker for predicting occurrence of AKI and its severity in pediatric patients undergoing cardiac surgery. Design A prospective observational study. Setting A single-institution university hospital. Participants All patients<18 years of age who underwent repair of congenital heart disease with cardiopulmonary bypass between July 2010 and July 2012 were included in the study. Neonates age<1 month were excluded from the study population. Interventions The association between uAlb and occurrence of AKI within 3 days after admission to the intensive care unit was investigated. Criteria from pediatric-modified Risk Injury Failure Loss and End-stage kidney disease (pRIFLE) were used to determine the occurrence of AKI. The value of uAlb was measured at intensive care unit admission immediately after cardiac surgery in all participants from whom a 5-mL urine sample was obtained. Measurements and Main Results Of 376 patients, AKI assessed by pRIFLE was identified in 243 (64.6%): 172 for risk (R; 45.7%), 44 for injury (I; 11.7%), and 27 for failure (F; 7.2%). One hundred thirty-three patients (35.4%) were classified as being without AKI (normal [N]) by pRIFLE. The concentration of uAlb was significantly higher in AKI patients than in non-AKI patients (median [interquartile range]): uAlb (μg/mL): 13.5 (6.4-39.6) v 6.0 (3.4-16), p<0.001; uAlb/Cr (mg/gCr): 325 (138-760) v 121 (53-269), p< 0.001. Conclusions The utility of uAlb for prompt diagnosis of AKI was shown. Obtaining uAlb measurements early after pediatric cardiac surgery may be useful for predicting the occurrence and severity of AKI.