Hallmarks of primary hyperoxaluria type 3 (PH3) are nephrolithiasis and hyperoxaluria. However, little is known about factors influencing stone formation in this disease. We characterized stone events and examined associations with urine parameters and kidney function in a PH3 population.
We retrospectively analyzed clinical, and laboratory data of 70 PH3 patients enrolled in the Rare Kidney Stone Consortium PH Registry.
Kidney stones occurred in 65/70 PH3 patients (93%). Among the 49 patients with imaging available, the median [IQR] number of stones was 4 [2, 5], with largest stone 7 mm [4, 10] at first imaging. Clinical stone events occurred in 62/70 (89%)) with median number of events per patient 3 [2,6], range 1-49. Age at first stone event was 3 years [0.99, 8.7]. Lifetime stone event rate was 0.19 events/year [0.12,0.38] during follow-up of 10.7 [4.2, 26.3] years. Among 326 total clinical stone events, 139 (42.6%) required surgical intervention. High stone event rates persisted for most patients through the 6th decade of life. Analysis was available for 55 stones: Pure calcium oxalate accounted for 69%, with mixed calcium oxalate and phosphate in 22%. Higher calcium oxalate supersaturation was associated with increased lifetime stone event rate after adjusting for age at first event [IRR, 95%CI] [1.23 (1.16, 1.32), P<.001]. By the 4th decade, eGFR was lower in PH3 patients than the general population.
Stones impose a lifelong burden on PH3 patients. Reducing urinary calcium oxalate supersaturation may reduce event frequency and surgical intervention.
The Journal of urology. 2023 Mar 08 [Epub ahead of print]
Muhammad G Arnous, Lisa Vaughan, Ramila A Mehta, Phillip J Schulte, John C Lieske, Dawn S Milliner
Divison of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota., Department of Quantitative Health Sciences, Mayo Clinic, Rochester, Minnesota.