Etiology, urine metabolic risk factors, and urine oxalate patterns in patients with significant hyperoxaluria and recurrent nephrolithiasis

Jonathan P. Moore, David J. Mauler, Gopal L. Narang, Karen L. Stern, Mitchell R Humphreys, Mira T. Keddis

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose: American Urology Association guidelines recommend genetic testing for patients with recurrent stones and urine oxalate > 75 mg/day. The goal of this study was to examine the treatment of patients in this category in a large multidisciplinary adult stone clinic. Methods: Patients were evaluated from a single institution between 2006 and 2019. Those with at least one level of urinary oxalate excretion (uOx) above 75 mg/day were identified. A chart review identified enteric risk factors and genetic testing results. Patients without an identifiable enteric cause were considered idiopathic. Results: A total of 4229 separate 24-h urine collections in 1302 patients were reviewed. At least one measurement of uOx above 75 mg/day was found in 103 (7.9%) patients. Enteric hyperoxaluria (EH) was seen in 28 (27%) and idiopathic hyperoxaluria (IH) in 76 (74%). 20 (71%) patients in the EH group had undergone gastric bypass. The median uOx was significantly higher level in the EH group (121.0 vs. 93.0 mg/day). For the entire cohort, there was a drop in uOx (− 33.8 mg/day) with medical and dietary therapy after a follow-up of 46.6 months. The final oxalate was higher in EH (88.9 vs. 60.1 mg/day). Only one patient had referral for genetic testing and was found to have primary hyperoxaluria type 2. Conclusions: The most common cause of significant hyperoxaluria in patients with recurrent nephrolithiasis remains idiopathic. Patients with IH have more significant improvement in uOx compared to EH; however, both groups had hyperoxaluria at last follow-up. Rate of genetic testing is low despite guideline recommendations.

Original languageEnglish (US)
JournalInternational Urology and Nephrology
DOIs
StateAccepted/In press - 2022

Keywords

  • Hyperoxaluria
  • Hyperoxaluria (primary)
  • Recurrent nephrolithiasis

ASJC Scopus subject areas

  • Nephrology
  • Urology

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