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Urinary oxalate and glycolate excretion in healthy infants and children
E P Leumann1, A Dietl, A Matasovic
1University Children's Hospital, Zürich, Switzerland.
Insights
Urinary oxalate and glycolate levels, crucial for assessing kidney health, decrease with age in children. Random urine samples are suitable for screening, but age-specific reference values are essential for accurate interpretation.
Area of Science:
- Biochemistry
- Pediatric Nephrology
- Clinical Chemistry
Background:
- Elevated urinary oxalate and glycolate can indicate metabolic disorders or kidney stone risk.
- Understanding age-related changes in these metabolites is vital for pediatric health assessment.
- Previous studies have not comprehensively analyzed these ratios across a wide pediatric age range.
Purpose of the Study:
- To determine the molar ratios of urinary oxalate and glycolate to creatinine in infants and children.
- To establish age-specific reference values for these ratios.
- To assess the suitability of random urine samples for screening.
Main Methods:
- Urine samples were collected from 26 infants and 27 children (aged 1-5 years) and 135 children (aged 5-16 years).
- Oxalate was quantified using oxalate oxidase; glycolate was measured via a colorimetric assay (chromotropic acid--sulphuric acid).
- Ratios were expressed as mmol/mol creatinine and analyzed on a log-normal basis.
Main Results:
- Both oxalate and glycolate ratios were highest in infants aged 0-6 months and decreased significantly with age.
- Mean oxalate ratios ranged from 147 (infants 0-6 months) to 22 (adolescents 16 years).
- Fasting and noon urine samples showed similar ratios, except for glycolate in the oldest group, suggesting random samples are adequate for screening.
Conclusions:
- Urinary oxalate and glycolate levels show a clear age-dependent pattern in children.
- Random urine samples can be used for screening these metabolites.
- Accurate interpretation necessitates the use of age-specific reference values derived from comparable analytical methods.
Abstract:
The molar ratios of oxalate and glycolate over creatinine were determined in single urine samples of 26 infants and 27 children aged 1-5 years. In 135 children aged 5-16 years, two urine specimens were collected, one before breakfast and one at noon. Oxalate was determined by oxalate oxidase, and glycolate was measured by a colorimetric method (improved chromatotropic acid--sulphuric acid assay after prior purification by cation and anion exchanger). Both ratios (expressed in mmol/mol creatinine and analysed on a log-normal basis) were highest in infants 0-6 months old [mean oxalate 147 (95% confidence interval: 60-360), mean glycolate 175 (72-425)]. The mean oxalate ratio was 72 mmol/mol (29-174) at the age of 7-24 months, 44 (19-101) at the age of 2-5 years and 22 (12-40) in adolescents aged 16 years. Molar glycolate ratios were higher, but disclosed the same pattern. Oxalate and glycolate ratios in fasting urines did not differ significantly from those in noon samples (except glycolate in the oldest age group). Oxalate ratios correlated well with glycolate ratios in children up to 5 years of age only. Random urine samples are thus suitable for screening. However, interpretation of data requires use of age-specific reference values that are based on comparable methods.