The risk of chronic kidney disease (CKD) and nephrolithiasis increases with higher levels of oxalate excretion in 24-h urine, warranting monitoring in specific populations, especially after malabsorptive bariatric surgery. However, implementation of systematic 24-h urine collection is challenging, so there is a need for alternative screening methods.
Using retrospective data from patients evaluated for the risk of urolithiasis, we assessed different thresholds for the urinary oxalate/creatinine (UOx/Creat) ratio to optimize the screening performance for hyperoxaluria diagnosis and urolithiasis risk using lithogenic risk surrogates.
Among 1264 patients referred for urolithiasis, 38% were excluded because urine collection was considered incomplete. The remaining 786 individuals were included in our analysis, of whom 16% exhibited hyperoxaluria. A UOx/Creat screening threshold between 35 and 45 μmol/mmol demonstrated good performance, depending on the clinical weighting for false-negative versus true-positive results and the cost/benefit ratio.
The UOx/Creat ratio is a promising tool in screening for hyperoxaluria-related complications. However, future research is needed to validate its performance and address the limitations identified to confirm its clinical relevance and effectiveness.
Our study shows that a simple test to measure the ratio of oxalate to creatinine in urine can help in identifying people at risk of kidney stones, especially for patients who have had weight-loss surgery. The test showed good screening performance, but more research is needed to confirm our findings.
European urology open science. 2025 Mar 28*** epublish ***
Pierre Letourneau, Lara Cabezas, Aurélie De Mul, Nadia Abid, Christelle Machon, Cécile Poussineau, Cécile Acquaviva, Justine Bacchetta, Laurence Derain-Dubourg, Sandrine Lemoine
Department of Nephrology, Dialysis, Hypertension, and Renal Function Exploration, Edouard Herriot Hospital, Hospices Civils de Lyon, Lyon, France., Department of Urology, Edouard Herriot Hospital, Hospices Civils de Lyon, Lyon, France., Department of Biochemistry and Molecular Biology, Hospices Civils de Lyon, Lyon, France., Reference Center for Rare Renal Diseases, Pediatric Nephrology-Rheumatology-Dermatology Unit, Hospices Civils de Lyon, Lyon, France.