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Kidney Week

Abstract: PO0601

Examining the Clinical Effectiveness of Calcium Oxalate Stone Treatments

Session Information

Category: Bone and Mineral Metabolism

  • 402 Bone and Mineral Metabolism: Clinical

Authors

  • Gutbrod, Joseph T., University of Chicago Division of the Biological Sciences, Chicago, Illinois, United States
  • Keys McKay, Charles C., 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
  • Prochaska, Megan, University of Chicago Division of the Biological Sciences, Chicago, Illinois, United States

Group or Team Name

  • 1 and 2 are co-first authors
Background

Lowering urine calcium oxalate (CaOx) supersaturation (SS) is a primary clinical focus for CaOx kidney stone (KS) prevention and can be achieved by increasing urine volume, or decreasing urine calcium or oxalate excretions. Common clinical strategies to do this include advising patients to increase fluid intake, restrict dietary sodium, restrict dietary oxalate, or prescribing a thiazide-type diuretic. Several of these strategies have been validated in the controlled setting of randomized trials but efficacy in the real-world clinical setting is less clear. We investigated the efficacy of these treatment strategies in a clinical setting, observing whether trial-based findings on CaOx KS treatment hold true.

Methods

We reviewed medical charts for 204 CaOx KS formers with idiopathic hypercalciuria from University of Chicago Kidney Stone Clinic. Patients had three 24-hour urine collections before an initial clinic visit and one follow up 24-hour urine collection. Data collected included initial treatment advice and 24-hour urine composition. We analyzed patient groups based on treatment advice and used descriptive statistics and t-tests to analyze changes in urine variables from pre- to post-advice.

Results

Compared to those who did not receive the advice, advice to increase fluid intake resulted in a larger pre- to post-advice increase in urine volume (0.6 vs. 0.09L/day, p<0.001) and decrease in CaOx SS (-3 vs. -1, p=0.001). Compared with those who did not receive the advice, advice to restrict dietary sodium alone resulted in a larger pre- to post-advice decrease in urine sodium (-28 vs 13mg/day, p=0.002) but there was no change in urine calcium or CaOx SS without concurrent thiazide. Thiazide prescription resulted in a significant pre- to post-advice decrease in urine calcium for patients who also sodium restricted (-99mg/day, p<0.001) and those who did not sodium restrict (-58mg/day, p<0.001) with a trend towards a larger decrease in those who did both (p=0.06). Thiazide prescription resulted in a significant pre- to post-advice decrease in urine CaOx SS for patients who also sodium restricted (-3.3, p<0.001) and those who did not (-2, p<0.001).

Conclusion

In a real-world clinical setting, advice to increase fluid intake fluid or a thiazide diuretic prescription and reduction in sodium intake lowered CaOx SS and CaOx KS risk in follow up.

Funding

  • NIDDK Support