Survivors of COVID-19 mostly recover from tubular proteinuria and acute kidney injury after hospital discharge

Abstract

The coronavirus disease 2019 (COVID-19) is associated with acute kidney injury (AKI) [1]. Additionally, early observations in China showed a high prevalence of proteinuria and hematuria in patients infected by SARSCoV-2. These findings have since been confirmed in other countries. Proteinuria might result from a proximal tubular dysfunction. COVID-19-induced AKI and proteinuria have been associated with poor short-term outcomes in hospitalized patients [2, 3]. However, the middleand longterm consequences of SARS-CoV-2 infection on kidney function remain unknown. In the present observational single-center study, we report the follow-up (F-U) of both proteinuria and estimated glomerular filtration rate (eGFR) in COVID-19 patients post hospital discharge [3]. All data were anonymized and the study had been approved by the Ethics Committee of ULiège Academic Hospital. Patients older than 18 years of age admitted to Liège Academic Hospital between March 28th and April 30th, 2020 with PCR-confirmed COVID-19, for whom data concerning total proteinuria and/or urine α1-microglobulin were available were included in our study. A detailed description of the methodology has been previously published [3]. Briefly, serum creatinine and total proteinuria before COVID-19 were also collected when available. Total proteinuria (expressed in mg/g of urine creatinine), urine α1microglobulin and β2-microglobulin were determined on a random spot. Proteinuria was staged according to the KDIGO (Kidney Disease Improving Global Outcomes). Urine α1-microglobulin was expressed in mg/g of urine creatinine with a pathological threshold at > 15 mg/g. Urine β2-microglobulin was expressed in mg/L, with a pathological threshold at > 0.19 mg/L. Hematuria was defined by the presence of more than 10 red blood cells per field. AKI during hospitalization (Hosp) was based on the KDIGO definition (after considering the serum level of creatinine at admission as the baseline value). Decreased kidney function was based on the CKD-Epidemiology equation (CKD-EPI) and using an age-calibrated definition. The same parameters were then followed after hospital discharge until August 28th, 2020 in the context of a global health follow-up of hospitalized COVID-19 patients established by the hospital. Data are expressed as median with quartiles. Comparison Antoine Bouquegneau and Justine Huart equally contributed as first authors.