ABSTRACT
BACKGROUND COVID-19 can be complicated by kidney disease, including focal segmental glomerulosclerosis (FSGS), interstitial nephritis, and acute kidney injury (AKI). Almost all known cases of COVID-19-associated glomerulonephritis have been in patients of African descent, with G1 or G2 apolipoprotein L1 (APOL1) risk alleles, and they presented collapsing type of FSGS. CASE REPORT We report a case of biopsy-confirmed non-collapsing FSGS with secondary acute interstitial nephritis and AKI in a young White man with APOL1 low-risk genotype, who had COVID-19 pneumonia. His past history included arterial hypertension, anabolic steroids, and high-protein diet. He fully recovered from type 1 respiratory failure and AKI after transfusion of COVID-19 convalescent plasma and intravenous treatment with dexamethasone administered for 16 days in a dose reduced from 16 to 2 mg/day. Due to progressing severe nephrotic proteinuria (22.6 g/24 h), intravenous methylprednisolone was administered (1500 mg divided in 3 pulses over 3 days) immediately followed by oral prednisone (0.6 mg/kg body weight), with dose reduced 19 weeks later and switched to cyclosporine A (4 mg/kg body weight). Kidney re-biopsy, at that time, showed a decrease in proportion of glomeruli affected with podocytopathy, but progression of interstitial lesions. After 23 weeks of therapy, partial remission of FSGS was attained and proteinuria dropped to 3.6 g/24 h. After 43 weeks, proteinuria decreased to 0.4 g/24 h and the serum creatinine concentration remained steady. CONCLUSIONS High-dose glucocorticoid therapy was effective in the initial treatment of COVID-19-related non-collapsing FSGS, but had no effect on interstitial changes. Introduction of cyclosporine A to the therapy contributed to remission of disease.