What is the spectrum of kidney pathology associated with COVID-19?

Kidney involvement occurs in almost one third of patients hospitalised with coronavirus disease 2019 (COVID-19) and is associated with increased disease severity. This review aims to outline the spectrum of kidney pathology involved in COVID-19. Literature was reviewed systematically on the databases Medline OVID and Scopus in search of case reports, case series, cohort studies and autopsy studies of patients with COVID-19 who underwent kidney biopsies. Studies were published between August 2020 and November 2021. Fourteen studies consisting of 159 patients were included in this review. Acute tubular necrosis is the most common pathology followed by collapsing glomerulopathy, occurring in 40.1% and 28.9% of patients respectively. Of the 46 patients with collapsing glomerulopathy, 44 were of African descent with high-risk apolipoprotein L1 genotypes. Less common glomerular diseases include membranous nephropathy, secondary focal segmental glomerulosclerosis, minimal change disease and primary focal segmental glomerulosclerosis occurring in 5%, 4.4%, 3.1% and 2.5% of patients respectively. Glomerulonephritis occurred in a minority of patients. Direct viral infection has not been found as a definitive aetiology. Acute kidney injury occurs frequently in hospitalised COVID-19 patients and is associated with increased morbidity and mortality. The mechanisms underpinning acute kidney injury are multifactorial. Acute tubular necrosis is the most common. Collapsing glomerulopathy is the most common glomerular injury and is strongly linked to apolipoprotein L1 genotypes. Improved understanding of COVID-19-related kidney pathologies can guide treatment to improve patient outcomes and reduce progression of chronic kidney disease. The longitudinal impact of COVID-19-related kidney disease requires further research.