Clinical Outcomes in Primary Hyperoxaluria Type 2

Primary hyperoxaluria type 2 (PH2) is a rare disorder characterized by the overproduction oxalate, which can lead to kidney stones, can ultimately renal failure.

In this study, datasets from 101 patients from 11 counties found in the European Hyperoxaluria Consortium (OxalEurope)—the largest PH2 cohort—were included. First symptoms were reported at a median age of 3.2 years with a mean diagnosis for index cases at 8.0 years. There was a median follow-up of 12.4 years.

Approximately 82% of cases presented with urolithiasis. A genetic analysis identified 18 novel mutations in the GRHPR gene. Of 238 spoturine 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%).

Twelve patients were lost to follow-up and median renal survival was 43.3 years. Approximately 50% of patients experienced chronic kidney disease (CKD) stage ≥2 and 24.7% had reached CKD5.

There were a reported 15 transplantations in 11 patients. Renal outcome did not correlate with genotype, biochemical parameters, or with the presence of nephrocalcinosis at presentation.

The authors concluded that 24-hour urine analysis provides an accurate diagnosis of PH2 and that the role of liver transplantation remains unclear.

Reference

Garrelfs SF, Peters-Sengers H, Groothoff J, et al. Primary hyperoxaluria type 2: new insight into clinical outcomes. J Am Soc Nephrol 30. 2019; Kidney Week 2019 Supplement.