Urinary reference values for stone risk factors in children.

Area of Science:

• Pediatric Nephrology
• Urology
• Clinical Chemistry

Background:

• Limited reference values exist for 24-hour urine stone risk factors in non-stone forming children.
• Understanding age-related changes in these factors is crucial for accurate diagnosis.

Purpose of the Study:

• To measure urinary stone risk factors in healthy children aged 3 to 18 years.
• To determine if age influences these risk factors in 24-hour urine samples.

Main Methods:

• 48 healthy children without a history of stone disease were recruited.
• 24-hour urine samples were analyzed, with chemistries adjusted for urinary creatinine and body weight.
• Subjects were stratified into four 5-year age groups.

Main Results:

• Urinary pH and volume decreased with increasing age.
• Adjusted urinary parameters (calcium, oxalate, uric acid, citrate, magnesium, sodium, phosphorus, potassium) showed a statistically significant decrease with age, except for calcium.
• Unadjusted parameters did not show significant age-related differences.

Conclusions:

• Urinary stone risk factors decline with age in healthy children.
• Normative data, adjusted for creatinine or body weight and stratified by age, can help identify abnormal stone risk factors in pediatric patients.
• This study provides valuable reference ranges for pediatric urolithiasis evaluation.