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The impact of urine pH on lithogenic risk profile in children with urolithiasis
Joanna Bagińska-Chyży1, Jan K Kirejczyk2, Tadeusz Porowski3
1Department of Pediatrics and Nephrology, Medical University of Bialystok, Waszyngtona Street 17, 15-274, Białystok, Poland. joasiabaginska14@wp.pl.
Insights
Maintaining a urine pH between 6.75 and 7.0 is crucial for pediatric stone formers. This pH range supports protective factors like citrate and magnesium, aiding in stone prevention.
Area of Science:
- Pediatric Nephrology
- Urology
- Metabolic Disorders
Background:
- Urinary pH impacts lithogenic substance solubility and excretion, but its metabolic associations in pediatric stone formers are not well understood.
- This study examines the link between urinary pH and metabolic risk factors in children and adolescents with urolithiasis.
Purpose of the Study:
- To investigate the association between urinary pH and various lithogenic risk factors in pediatric stone formers.
- To compare these associations with those in healthy pediatric controls.
Main Methods:
- A cohort of 400 pediatric stone formers (ages 3-18) and 372 healthy controls underwent 24-h urine collection.
- Analyzed urinary pH, BMI z-score, urine volume, osmolality, creatinine, GFR, and excretion of calcium, oxalate, phosphate, magnesium, citrate, and uric acid.
- Evaluated two lithogenic risk indices: Bonn Risk Index (BRI) and Upper Metastable Limit osmolality (UMLOsm).
Main Results:
- Pediatric stone formers showed higher urine volume, oxalate, calcium, ionized calcium, uric acid, and BRI than controls.
- Controls had higher urinary citrate, osmolality, and UMLOsm.
- Lower urine pH correlated with higher BMI z-scores and reduced urine volume; calcium excretion peaked at pH 7, while citrate and magnesium increased between pH 6.75-7.0.
Conclusions:
- Individualized dietary and lifestyle advice is essential for pediatric stone formers.
- Recommendations include maintaining a healthy BMI, adequate hydration, and a urine pH between 6.75 and 7.0.
- This pH range appears to promote protective factors like citrate and magnesium, potentially reducing stone recurrence.
Background:
Urinary pH is known to influence the solubility and excretion of lithogenic substances, yet its relationship with other metabolic parameters in pediatric stone formers remains underexplored. This study investigated the association between urinary pH and lithogenic risk factors in children and adolescents with urolithiasis compared to healthy controls.
Methods:
A total of 400 pediatric patients (ages 3-18 years) with urinary stones and 372 age- and sex-matched healthy controls were included. All participants completed a 24-h urine collection for comprehensive metabolic analysis. Parameters assessed included urinary pH, BMI z-score, urine volume, osmolality, excreted creatinine, GFR, and urinary excretion of calcium, ionized calcium, oxalate, phosphate, magnesium, citrate, and uric acid. Two lithogenic risk indices were also evaluated: Bonn Risk Index (BRI) and Upper Metastable Limit osmolality (UMLOsm).
Results:
Stone-formers demonstrated significantly higher urine volume, oxalate, calcium, ionized calcium, uric acid, and BRI compared to controls. In contrast, controls exhibited higher levels of urinary citrate, osmolality, and UMLOsm. Lower urine pH was associated with higher BMI z-scores and reduced urine volume. Calcium excretion increased with urine pH up to 7 before declining, whereas citrate and magnesium excretion rose at pH levels between 6.75 and 7.0, indicating a potential protective effect.
Conclusions:
Our findings highlight the importance of individualized dietary and lifestyle guidance in pediatric stone formers, with a focus on maintaining a healthy BMI, adequate hydration, and urine pH between 6.75 and 7.0 to support protective factors like citrate and magnesium.
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