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

BACKGROUND AND AIMS: Proteinuria, hematuria and acute kidney injury (AKI) are frequently observed in hospitalized patients with COVID-19. However, few data are available on these parameters after hospital discharge. METHOD: This retrospective, observational and monocentric study included 153 hospitalized patients, in whom urine total proteinuria and a1-microglobulin (a marker of tubular injury) were measured. Thirty patients died. Among the 123 survivors, follow-up urine and creatinine analyses were available for 72 patients (after a median of 51 [19;93] days following hospital discharge). RESULTS: The median proteinuria at hospitalization and follow-up (n=72) was 419 [239;748] and 79 [47;129] mg/g, respectively (p<0.0001). The median concentrations of urinary a1-microglobulin (n=66) were 50 [25;81] and 8 [0;19] mg/g, respectively (p<0.0001). Estimating glomerular filtration rate (eGFR) was lower during the hospitalization compared to the follow-up: 81 [62;92] versus 87 [66;98] mL/min/ 1.73m2 (p=0.0222). At follow-up, a decreased renal function was observed in 10/72 (14%) of patients, with 50% of them presenting decreased renal function before COVID-19 hospitalization and others developing severe AKI and/or proteinuria during hospitalization. CONCLUSION: In most hospitalized patients with COVID-19, proteinuria and eGFR significantly improved after hospital discharge. Only patients who developed severe AKI and/or heavy proteinuria will require a specific follow-up by nephrologists.