Protein Intake and High Uric Acid Stone Risk

Area of Science:

• Nephrology
• Urology
• Metabolic Research

Background:

• Uric acid nephrolithiasis is a significant clinical concern.
• Understanding metabolic differences between pure and impure uric acid stone formers is crucial for targeted treatment strategies.

Purpose of the Study:

• To investigate the metabolic distinctions between individuals who form pure uric acid stones versus those who form impure uric acid stones.
• To identify risk factors associated with pure uric acid kidney stone formation.

Main Methods:

• Retrospective analysis of 1996-2021 data from Yale Urology and Nephrology Clinics.
• Comparison of demographics and 24-hour urine chemistries between pure (stones <50% uric acid) and impure (stones ≥50% uric acid) uric acid stone formers.
• Logistic regression analysis controlling for age, sex, race, ethnicity, body mass index, and comorbid conditions.

Main Results:

• Pure uric acid stone formers were older, heavier, and more likely to have chronic kidney disease (CKD).
• After adjusting for confounders, pure uric acid stone formers exhibited lower urinary pH and lower urine citrate.
• Elevated urine urea nitrogen and sulfur, indicative of higher protein intake, were also observed in pure uric acid stone formers, persisting even after controlling for CKD.

Conclusions:

• Pure uric acid stone formation is associated with diminished kidney function and increased dietary protein intake.
• Modifying dietary protein intake may represent a viable strategy to mitigate the risk of pure uric acid kidney stones.