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Urinary oxalate and glycolate excretion and plasma oxalate concentration
T M Barratt1, G P Kasidas, I Murdoch
1Department of Paediatric Nephrology, Institute of Child Health, London.
Insights
Establishing reliable reference ranges for urinary oxalate is crucial for diagnosing primary hyperoxaluria in children. This study provides essential data on urinary, plasma, and amniotic fluid oxalate levels in normal pediatric populations.
Area of Science:
- Biochemistry
- Pediatrics
- Nephrology
Background:
- Diagnosing primary hyperoxaluria in young children is challenging due to the absence of established reference ranges for urinary oxalate excretion, particularly in infants.
- Accurate reference values are vital for differentiating between normal physiological oxalate levels and those indicative of disease.
Purpose of the Study:
- To establish reliable reference ranges for urinary oxalate and glycolate excretion in normal children across different age groups.
- To determine normal plasma oxalate concentrations in children and assess its relationship with age and chronic renal failure.
- To measure amniotic fluid oxalate concentration in uncomplicated pregnancies.
Main Methods:
- Collected data on urinary oxalate and glycolate excretion from 137 normal children.
- Measured plasma oxalate concentration in 33 normal children and 53 with chronic renal failure.
- Assessed amniotic fluid oxalate concentration in 63 uncomplicated pregnancies.
- Analyzed urinary oxalate:creatinine molar ratios, plasma oxalate concentrations, and amniotic fluid oxalate levels.
Main Results:
- Urinary oxalate:creatinine molar ratios exhibited log-normal distribution across age groups (<1 year, 1-5 years, 5-12 years, >12 years).
- Geometric mean plasma oxalate concentration in normal children was 1.53 mumols/l, independent of age.
- Plasma oxalate:creatinine molar ratio in normal children and those with chronic renal failure was 0.033, unaffected by age or renal function.
- Mean amniotic fluid oxalate concentration was 19.0 mumols/l.
Conclusions:
- The study provides critical reference data for urinary, plasma, and amniotic fluid oxalate.
- These findings will aid in the accurate diagnosis of primary hyperoxaluria in pediatric patients.
- Established ranges are essential for clinical assessment and management of hyperoxaluric conditions.
Abstract:
The diagnosis of primary hyperoxaluria in young children is hampered by the lack of a reliable reference range for urinary oxalate excretion, especially in infants. We present data on urinary oxalate and glycolate excretion in 137 normal children, on the plasma oxalate concentration in 33 normal children and 53 with chronic renal failure, and on amniotic fluid oxalate concentration in 63 uncomplicated pregnancies. The urinary oxalate:creatinine molar ratios were log normally distributed: mean (range) values were less than 1 year 0.061 (0.015-0.26), 1-5 years 0.036 (0.011-0.12), 5-12 years 0.030 (0.0059-0.15), and greater than 12 years 0.013 (0.0021-0.083). Geometric mean (range) plasma oxalate concentration in the normal children was 1.53 (0.78-3.02) mumols/l and was independent of age. The mean (SD) plasma oxalate: creatinine molar ratio in these normal children and 50 with chronic renal failure was 0.033 (0.013), and was independent of age and renal function. Mean (SD) amniotic fluid oxalate concentration was 19.0 (4.3) mumols/l.