Urinary Oxalate Excretion Associated with Risk of Progression of CKD and ESRD

San Diego—Oxalate nephropathy, a complication of oxalate metabolism (primary hyperoxaluria), oxalate over-absorption (enteric hyperoxaluria), and ingestion of large amounts of oxalate or its precursors, results in kidney failure. Sushrut S. Waikar, MD, and colleagues conducted an analysis to test the hypothesis that there would be an association between progression of chronic kidney disease (CKD) and higher urinary oxalate excretion, even within the typical range of excretion.

The researchers reported results of the analysis during an oral presentation at Kidney Week 2018. The presentation was titled Urinary Oxalate Excretion and the Risk of ESRD and CKD Progression.

Measurements of 24-hour urinary oxalate excretion in stored specimens from 3123 participants in the CRIC (Chronic Renal Insufficiency Cohort) study were taken. Baseline estimated glomerular filtration rate (eGFR) was 43 mL/min/1.72 m2. CRIC participants were followed longitudinally for incident end-stage renal disease (ESRD) and/or halving of eGFR. Cox proportional hazards models were used to determine whether urinary oxalate excretion was associated with (1) incident ESRD and (2) progression of CKD, defined as halving of eGFR or incident ESRD. Adjustments in multivariable models included demographic, clinical, and laboratory values.

The median 24-hour oxalate excretion in the CRIC participants was 18.6 mg. Cross sectionally, there was a correlation between higher oxalate excretion and lower baseline eGFR (correlation coefficient [r]=–0.1; P<.001) and greater albuminuria (r=0.15; P<.001). In prospective multivariable-adjusted analyses, participants in the highest quintile of oxalate excretion had a 1.41-fold (95% confidence interval [CI], 1.09-1.83) higher risk of ESRD and a 1.28-fold (95% CI, 1.02-1.61) higher risk of progression of CKD (P<.001).

“Among individuals with CKD, higher baseline urinary oxalate excretion is associated with greater risk of ESRD and CKD progression. Oxalate excretion should be tested as a potentially modifiable risk factor for progression of kidney disease,” the researchers said.

Source: Sushrut WS, Lieske JC, Dawei X, et al. Urinary oxalate excretion and the risk of ESRD and CKD progression. Abstract of an oral presentation (TH-OR082) at the American Society of Nephrology Kidney Week 2018, October 25, 2015, San Diego, California.