Increased Rates of Supplement-Associated Oxalate Nephropathy During COVID-19 Pandemic.

Introduction: Causes of secondary oxalate nephropathy include enteric dysfunction and excessive intake of oxalate or oxalate precursors. During the COVID-19 pandemic, there has been a dramatic rise in sales of supplements and vitamin C, during which time we observed an apparent increase in the proportion of ingestion-associated oxalate nephropathy. Methods: We retrospectively reviewed secondary oxalate nephropathy and compared pre-pandemic (2018-2019) and pandemic (2020-early 2022) time periods. Results: We identified 35 patients with kidney biopsy proven (30 native, 5 allograft) oxalate nephropathy at a single academic institution. Supplement-associated oxalate nephropathy comprised a significantly higher proportion of cases during COVID-19 pandemic compared with the preceding 2 years (44% vs. 0%, P = 0.002), and was associated with use of vitamin C, dietary changes, and supplements. Oxalate nephropathy in the kidney allograft, in contrast, remained associated with enteric hyperoxaluria, antibiotic use, and dehydration. Many patients had diabetes mellitus (57%), hypertension (40%) and/or pre-existing chronic kidney disease (CKD, 49%). Of 9 patients in which the potentially causative ingestion was identified and removed, 8 experienced improvement in kidney function. Conclusion: There was a shift toward supplements rather than enteric hyperoxaluria as a leading cause of secondary oxalate nephropathy during the COVID-19 pandemic. Kidney outcomes are better than those observed for enteric hyperoxaluria, if the offending agent is identified and removed.

Increased rates of supplement-associated oxalate nephropathy during COVID-19 pandemic

Introduction Causes of secondary oxalate nephropathy include enteric dysfunction and excessive intake of oxalate or oxalate precursors. During the COVID-19 pandemic, there has been a dramatic rise in sales of supplements and vitamin C, during which time we observed an apparent increase in the proportion of ingestion-associated oxalate nephropathy. Methods We retrospectively reviewed secondary oxalate nephropathy and compared pre-pandemic (2018 - 2019) and pandemic (2020 - early 2022) eras. Results We identified 35 patients with kidney biopsy proven (30 native, 5 allograft) oxalate nephropathy at a single academic institution. Supplement-associated oxalate nephropathy comprised a significantly higher proportion of cases during COVID-19 pandemic compared with the preceding 2 years (44% vs. 0%, p=0.002), and was associated with use of vitamin C, dietary changes, and supplements. Oxalate nephropathy in the kidney allograft, in contrast, remained associated with enteric hyperoxaluria, antibiotic use, and dehydration. Many patients had diabetes mellitus (57%), hypertension (40%) and/or pre-existing chronic kidney disease (49%). Of 9 patients in which the potentially causative ingestion was identified and removed, 8 experienced improvement in kidney function. Conclusion There was a shift toward supplements rather than enteric hyperoxaluria as a leading cause of secondary oxalate nephropathy during the COVID-19 pandemic. Kidney outcomes are better than those observed for enteric hyperoxaluria, if the offending agent is identified and removed.

Multicenter Clinicopathologic Correlation of Kidney Biopsies Performed in COVID-19 Patients Presenting With Acute Kidney Injury or Proteinuria.

RATIONALE & OBJECTIVE: Kidney biopsy data inform us about pathologic processes associated with infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We conducted a multicenter evaluation of kidney biopsy findings in living patients to identify various kidney disease pathology findings in patients with coronavirus disease 2019 (COVID-19) and their association with SARS-CoV-2 infection. STUDY DESIGN: Case series. SETTING & PARTICIPANTS: We identified 14 native and 3 transplant kidney biopsies performed for cause in patients with documented recent or concurrent SARS-CoV-2 infection treated at 7 large hospital systems in the United States. OBSERVATIONS: Men and women were equally represented in this case series, with a higher proportion of Black (n=8) and Hispanic (n=5) patients. All 17 patients had SARS-CoV-2 infection confirmed by reverse transcriptase-polymerase chain reaction, but only 3 presented with severe COVID-19 symptoms. Acute kidney injury (n=15) and proteinuria (n=11) were the most common indications for biopsy and these symptoms developed concurrently or within 1 week of COVID-19 symptoms in all patients. Acute tubular injury (n=14), collapsing glomerulopathy (n=7), and endothelial injury/thrombotic microangiopathy (n=6) were the most common histologic findings. 2 of the 3 transplant recipients developed active antibody-mediated rejection weeks after COVID-19. 8 patients required dialysis, but others improved with conservative management. LIMITATIONS: Small study size and short clinical follow-up. CONCLUSIONS: Cases of even symptomatically mild COVID-19 were accompanied by acute kidney injury and/or heavy proteinuria that prompted a diagnostic kidney biopsy. Although acute tubular injury was seen among most of them, uncommon pathology such as collapsing glomerulopathy and acute endothelial injury were detected, and most of these patients progressed to irreversible kidney injury and dialysis.