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Kidney Week

Abstract: PO1608

Outcome of Primary Hyperoxaluria Type 3: Clinics, Diagnostics, and Follow-Up

Session Information

Category: Genetic Diseases of the Kidneys

  • 1002 Genetic Diseases of the Kidneys: Non-Cystic

Authors

  • Martin Higueras, Cristina, Dept. Ciencias Médicas Básicas, Fac. Medicina, Universidad de la Laguna, Tenerife, Spain
  • Garrelfs, Sander F., Amsterdam Medical Center, Amsterdam, Netherlands
  • Beck, Bodo B., Institute of Human Genetics, University Hospital Cologne, Cologne, Germany
  • Zaniew, Marcin, University of Zielona Gora, Zielona Gora, Poland
  • Sikora, Przemyslaw, Department of Pediatric Nephrology, Medical University of Lublin, Lublin, Poland
  • Hoppe, Bernd, German Hyperoxaluria Center, Bonn, Germany
Background

Primary hyperoxaluria type 3 (PH3) is said to be the most benign form of PH and the risk of chronic kidney disease (CKD) and even end stage renal disease (ESRD) is reported to be low. We collected clinical, diagnostic and follow up data from our PH3 patients to evaluate the true disease characteristics.

Methods

We retrospectively screened the OxalEurope Registry for data of PH3 patients known to the German Hyperoxaluria Center and analyzed them for clinical and laboratory parameters.

Results

From the 90 PH3 patients enrolled in the OxalEurope Registry, 45 had all laboratory analysis done at the Hyperoxaluria Center (3-45 years of age, 23 males). Genetically confirmed diagnosis revealed 21 different biallelic mutations in HOGA1. The main symptom was recurrent urolithiasis, most prominently found in the first 3 years of life (>25% of patients). Nephrocalcinosis was seen in 7 patients. Mean follow up for all patients was 7.76 (0.25-34) years, median age at first symptom was 0.96 (0.17-10) and median age at diagnosis (based on genetics) was 4.57 (0.25-16.86) years. Not all patients experienced clinical remission: 3/6 patients > 20 years of age have ongoing kidney stone development. A high amount of stone removal procedures during the first years of life, but also later in life was observed. Urinary oxalate (Uox) excretion was significantly and continuously elevated over time. There was no significant difference in Uox between PH1 (1.37 mmol/1.73m2/24h), PH2 (1.4 mmol/1.73m2/24h) and PH3 (1.13 mmol/1.73m2/24h) with the exception of a lower Uox in PH1 patients sensitive to B6 medication (0.94 mmol/1.73m2/24h, p<0.05). A decline in kidney function was observed, which was related to a decreased clearance of oxalate. Nine patients had CKD stages 2 or 3. One patient showed a significant decline in eGFR over a period of 15 years (134 to 68.1 ml/min/1.73m2), which we would relate several lithotripsy procedures (n=16), but also ongoing hyperoxaluria.

Conclusion

Our analysis from a subgroup of European PH3 patients provides additional information on clinical outcome. PH3 patients seem to have the highest kidney stone burden during the first years of life, but they do not stop producing stones. Some PH3 patients progress to CKD and to loss of kidney function over time. Uox is comparable to non B6 responsive PH1 and also to PH2 patients.

Funding

  • Commercial Support