Primary hyperoxaluria: results of a retrospective survey of the diagnostic practices of nephrologists

Introduction: Primary hyperoxalurias (PH) are rare and serious genetic diseases. Their prognosis is improved with early medical management. However, diagnosis often occurs at the end-stage of renal failure. To understand this delay, collecting real-world data on the clinical practices of nephrologists may be helpful.

Materials and methods: Between October 2021 and October 2022, a retrospective survey was conducted in France among 76 nephrologists to assess management practices for patients with chronic kidney disease (CKD) of unknown aetiology, associated with urinary lithiasis and/or nephrocalcinosis. Data on patient profiles, tests conducted, diagnoses considered, and management of suspected PH cases were collected.

Results: 97% of patients (n = 386/400) underwent a renal examination, 92% (n = 370/400) a thorough urinary check-up, and 65% (n = 260/400) had an interpretable oxaluria value from a 24-hour urine sample (Uox24h). Of these 260 patients, 50% (n = 130/260) had Uox24h > 500 µmol/24 h: 23% (n = 30/130) were suspected of PH by the nephrologists, and 15% (n = 19/130) were referred for genotyping. Considering all criteria, 52 patients were suspected of PH (42% of whom did not have Uox24h > 500 µmol/24 h), and 33% (n = 17/52) were not referred for genotyping.

Discussion: The survey highlights nephrologists' adherence to recommendations for prescribing biological tests. However, in cases of hyperoxaluria or suspected PH, genotyping was not always prescribed. The barriers to this prescription need further exploration.