Long-term renal consequences of COVID-19. Emerging evidence and unanswered questions

COVID-19 infection is associated with a high burden of acute or acute on chronic kidney injury (AKI), particularly in critically ill patients. Given the large numbers of COVID-19 survivors, characterization of long-term adverse kidney effects of COVID-19 have important implications for post-COVID-19 care.

This narrative review provides a summary of epidemiologic evidence for post-COVID kidney disorders.

Precise post-COVID renal data are scarce. The true burden of long-COVID chronic kidney disease (CKD) remains unknown owing to under-recognition, under-diagnosis, clinical heterogeneity of patients, incomplete follow-up, and temporal trends in critical COVID-19 disease across waves of the pandemic. Collectively, the few well-designed studies assessing the impact of long-COVID on kidney health found that the overwhelming majority of patients with normal renal function at admission and without AKI during acute COVID-19 disease preserved kidney function. Post-infection kidney function trajectories of patients who experience a loss of renal function vary. Kidney function may decline gradually even in non-hospitalized patients, hospitalized patients may experience a rapid loss of kidney function 6-12 months after COVID-19 diagnosis or hospital discharge resulting from AKI during the acute phase of the disease. End-stage renal disease may occur after non-recovery from AKI and rapid progression of pre-existing CKD. Multiple mechanisms may trigger post-COVID CKD including maladaptive repair after AKI, or progression of renal lesions of systemic co-morbidities, persistence of the virus and dysregulation of inflammatory cytokines.

The COVID-19 pandemic has significantly impacted and may continue to have an impact on kidney health. Patients at risk have a higher propensity to develop critical COVID-19 disease. Post-COVID-19 care must pay close attention to renal function in patients discharged from hospital.