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Abstract: PO0603

Factors Reducing Kidney Stone Risk in Patients with Enteric Hyperoxaluria (EH)

Session Information

Category: Bone and Mineral Metabolism

  • 402 Bone and Mineral Metabolism: Clinical

Authors

  • Prochaska, Megan, University of Chicago Division of the Biological Sciences, Chicago, Illinois, United States
  • Bianco, Julianna, University of Chicago Division of the Biological Sciences, Chicago, Illinois, United States
  • Chu, Francesca M., University of Chicago Division of the Biological Sciences, Chicago, Illinois, United States
  • Worcester, Elaine M., University of Chicago Division of the Biological Sciences, Chicago, Illinois, United States
Background

There have been no trials examining efficacy of interventions aimed at decreasing stone risk in patients with EH. We drew upon data for patients in a kidney stone clinic who were treated with consistent methodologies over time. We asked how doctors made therapeutic choices and which therapies were effective at decreasing stone risk.

Methods

We selected 100 patients with EH from the Kidney Stone Evaluation and Treatment Program at the University of Chicago between 1970 and 2018. We analyzed 24-hour urine collections before and after patients’ first clinic visit using multivariate linear regression and t-tests to compare effects of fluid intake and oxalate-focused interventions on outcomes.

Results

Patients told to increase fluid intake had low baseline urine volumes; volume increased from 1.3 to 2.0 L/day (p < 0.001). In those not told to increase fluid intake urine volume increased from 1.7 to 2.0 L/day (p = 0.003). Volume increased more in the advice group (p = 0.03).

No interventions aimed at reducing oxalate absorption (low fat diet, calcium supplement, increased diet calcium, cholestyramine, and low oxalate diet) had a significant effect on urine oxalate. In those getting advice, urine oxalate was 88 mg/day at baseline and 91 mg/day on follow-up (p = 0.90) compared with 50 mg/day at baseline and 51 mg/day on follow-up (p = 0.77) in the non-intervention group.

In a multivariate model, fluid intake advice was associated with a decrease in calcium oxalate supersaturation (95% CI -4.3 to -0.8), while oxalate-focused interventions were not (95% CI -1.2 to 2.3).

Conclusion

Physicians chose treatments based on baseline urine characteristics. Advice to increase fluid intake is associated with decreased risk of stone formation. Interventions aimed at reducing oxalate absorption are not associated with a decreased risk of stone formation on follow-up. This lack of effect may be the result of patient physiology or lack of compliance with treatments and advice.

Effect of advice to increase fluid intake (left panel) or lower oxalate absorption (right panel) in stone formers with EH.

Funding

  • NIDDK Support