Clinical and histopathological features of acute kidney injury in adult-onset minimal change nephrotic syndrome

Background Acute kidney injury (AKI) is a common complication of minimal change nephrotic syndrome (MCNS), particularly in adults. To predict development of AKI, as defined by the Kidney Disease Improving Global Outcomes classification, we investigated clinical and histopathological features of adult-onset MCNS patients. Methods A retrospective study was conducted with biopsy-proven adult-onset MCNS patients treated with corticosteroids. Results A total of 58 MCNS patients [49 (24-71) years old, 38 males] were diagnosed using kidney biopsy findings from 2005 to 2018 at Osaka City University Hospital, of whom 24 (41.4%) were found to be complicated with AKI. Age, urinary protein, increased body weight (difference from admission to discharge), and histopathological scores were significantly greater in patients with as compared to without AKI, while urinary protein, increased body weight, and interstitial edema score were significantly associated with AKI development [OR 1.55 (95% CI 1.04-2.31), 1.37 (95% CI 1.03-1.81), 20.7 (95% CI 1.76-243), respectively]. Of the 24 MCNS patients with AKI, 10 underwent transient hemodialysis treatment. Although histopathological features were not different, the time interval between disease onset and kidney biopsy was significantly longer for MCNS patients complicated with AKI requiring hemodialysis as compared to those for whom that was not required [32 (24-46) vs. 13 (10-23) days, p = 0.034]. Conclusion These results indicate that urinary protein, increased body weight, and interstitial edema score are important information for predicting development of AKI in adult-onset MCNS patients.