24-h uric acid excretion and the risk of kidney stones

Abstract

There is uncertainty about the relation between 24-h urinary uric acid excretion and the risk of calcium oxalate nephrolithiasis. In addition, the risk associated with different levels of other urinary factors needs clarification. We performed a cross-sectional study of 24-h urine excretion and the risk of kidney stone formation in 3350 men and women, of whom 2237 had a history of nephrolithiasis. After adjusting for other urinary factors, urinary uric acid had a significant inverse association with stone formation in men, a marginal inverse association with risk in younger women, and no association in older women. The risk of stone formation in men and women significantly rose with increasing urine calcium and oxalate, and significantly decreased with increasing citrate and urine volume, with the change in risk beginning below the traditional normal thresholds. Other urinary factors were also associated with risk, but this varied by age and gender. Our study does not support the prevailing belief that higher urine uric acid excretion increases the risk for calcium oxalate stone formation. In addition, the current definitions of normal levels for urinary factors need to be re-evaluated.

Fluid Intake for Kidney Disease Prevention

“…In this study of Canadian adults, the average urine output was 1.6 L, consistent with average urine output of healthy adults (10,15,16). In the highest urine output group, urine output exceeded 3 L/d or twice the average urine output.…”

Dietary and Lifestyle Factors and Medical Conditions Associated with Urinary Citrate Excretion

“…Lower urinary citrate excretion is a known modifiable risk factor for calcium oxalate nephrolithiasis (1,2) and associated with both prevalent hypertension (3) and greater insulin resistance (4). However, the independent associations of several dietary and lifestyle factors and medical conditions with urinary citrate excretion are unclear.…”

Investigação de nefrolitíase no Oeste do Paraná

“…Low fluid ingestion and urinary pH below 5.5 favor the precipitation in acidic urine 28,37 . Hyperuricosuria was detected in 27.6% of the metabolic disorders observed in patients.…”

“…Hypercalciuria may be associated with hypophosphatemia due to mutations in phosphorus /sodium cotransporter proteins, encoded by the NPT2a gene [23][24][25] . In children with hypercalciuria, the prevalence of renal lithiasis in the family ranges from 46 to 49% [26][27][28] .…”

“…Hypocitraturia is a metabolic abnormality found in 20 to 60% of the patients with nephrolithiasis 28,33,34 . In this study, such change was observed in 23.5% of the metabolic disorders.…”