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Uric acid excretion in children with urolithiasis
L A Miller1, H N Noe, F B Stapleton
1Department of Pediatrics, University of Tennessee, Memphis.
Insights
Excessive urinary uric acid is rarely a risk factor for pediatric urolithiasis. Studies show uric acid excretion levels are similar across different types of kidney stones in children.
Area of Science:
- Pediatric Nephrology
- Urology
- Metabolic Disorders
Background:
- Urolithiasis is a significant health concern in children.
- Hyperuricuria, or excessive uric acid in urine, is a potential risk factor for stone formation.
- Understanding uric acid excretion patterns is crucial for managing pediatric kidney stones.
Purpose of the Study:
- To investigate whether hyperuricuria is a risk factor in children diagnosed with urolithiasis.
- To compare uric acid excretion in children with different types of kidney stones, including calcium oxalate and uric acid stones.
- To assess the impact of dietary sodium on uric acid excretion in children with hypercalciuria.
Main Methods:
- Assessed urinary uric acid excretion in 38 children with urolithiasis.
- Measured uric acid excretion per deciliter of glomerular filtration rate and fractional excretion.
- Analyzed stone composition and patient demographics, including cases of cystinosis.
Main Results:
- Urinary uric acid excretion and fractional excretion were similar in children with hypercalciuria and calcium oxalate stones, idiopathic calcium oxalate urolithiasis, and uric acid urolithiasis.
- No children with calcium urolithiasis exhibited excessive urinary uric acid excretion.
- Dietary sodium increase did not significantly alter uric acid excretion in children with hypercalciuria.
Conclusions:
- Excessive urinary uric acid excretion is infrequently an additional risk factor in pediatric calcium urolithiasis.
- Dietary sodium chloride does not appear to strongly influence urinary uric acid excretion in children with hypercalciuria.
Abstract:
Urinary uric acid excretion was assessed in 38 children to determine whether hyperuricuria was a risk factor in children with urolithiasis. Uric acid excretion (measured per deciliter glomerular filtration rate), and fractional excretion of uric acid were similar in 27 children with hypercalciuria and calcium oxalate urinary stones, in six children with idiopathic calcium oxalate urolithiasis, and in five with uric acid urolithiasis, of whom four were white boys and one was an Asian girl. One boy with a urate stone had cystinosis. Serum uric acid concentrations exceeded 6.0 mg/dl (360 mumol/L) in two children with hypercalciuria and in two patients with idiopathic calcium oxalate urolithiasis. None of the children with calcium urolithiasis had excessive urinary excretion of uric acid. In children with hypercalciuria, uric acid excretion did not change significantly when dietary sodium was increased from 1.0 to 5.0 gm/1.73 m2. We conclude that excessive urinary uric acid excretion is seldom an additional risk factor in children with calcium urolithiasis and that dietary sodium chloride does not have a strong influence on urinary excretion of uric acid in children with hypercalciuria.