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Kidney Week

Abstract: TH-PO760

Primary Hyperoxaluria Type 2: New Insight into Clinical Outcomes

Session Information

  • Pediatric CKD
    November 07, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
    Abstract Time: 10:00 AM - 12:00 PM

Category: Pediatric Nephrology

  • 1700 Pediatric Nephrology

Authors

  • Garrelfs, Sander F., Amsterdam UMC (Academic Medical Center), Amsterdam, Netherlands
  • Peters-Sengers, Hessel, Amsterdam UMC (Academic Medical Center), Amsterdam, Netherlands
  • Groothoff, Jaap, Amsterdam UMC (Academic Medical Center), Amsterdam, Netherlands
  • Beck, Bodo B., University of Cologne Medical Center, Cologne, Germany
  • Oosterveld, Michiel Js, Amsterdam UMC (Academic Medical Center), Amsterdam, Netherlands
  • Cochat, Pierre, Université ClaudeBernard Lyon1-, Bron, France
  • Lipkin, Graham W., Queen Elizabeth Hospital, Bimingham, UK, Birmingham, United Kingdom
  • Salido, Eduardo C., Hospital Universitario Canarias, La Laguna, Tenerife, Spain
  • Hoppe, Bernd, University Hospital Bonn, Bonn, Germany
  • Hulton, Sally, Birmingham Childrens'' Hospital, Birmingham, United Kingdom

Group or Team Name

  • on behalf of the OxalEurope consortium
Background

Primary hyperoxaluria type 2 (PH2) is a rare inherited disorder of glyoxylate metabolism causing nephrocalcinosis, renal stone formation and ultimately renal failure. PH2 had previously been considered to have a more favorable prognosis than PH1, but earlier reports are limited by low patient numbers and short follow up periods.

Methods

This study is based on gathered data from the European Hyperoxaluria Consortium (OxalEurope), encompassing the largest known PH2 cohort worldwide, providing a unique cohort enabling the description of longer-term outcomes in this rare disease.

Results

The dataset contained 101 patients from eleven countries. Median follow up was 12.4 years. Median ages at first symptom and diagnosis for index cases were 3.2 years and 8.0 years, respectively. Urolithiasis was the most common presenting feature (82.8%). Genetic analysis revealed 18 novel mutations in the GRHPR gene. Of 238 spot-urine analyses, 23 (9.7%) were within normal range as compared to less than 4% of 24-hour urine collections. Median intra-individual variation of 24-hour oxalate excretion was substantial (34.1%). At time of review 12 patients were lost to follow-up; 45 of 89 (50.6%) experienced chronic kidney disease (CKD) stage ≥2 and 22 patients (24.7%) had reached CKD5. Median renal survival was 43.3 years. 15 transplantations in 11 patients are described. Renal outcome did not correlate with genotype, biochemical parameters nor with the presence of nephrocalcinosis at presentation.

Conclusion

PH2 is not a benign disease and accurate diagnosis by 24-hour urine analysis and careful follow-up is required, in order to attempt to ameliorate its poor outcome. The role of liver transplantation remains unclear although it is evident that renal transplantation alone does not cure the disease.