Urinary oxalate and glycolate excretion and plasma oxalate

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 <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 >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) tmol/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) ,mol/l. Department of Paediatric Nephrology, Institute of Child Health, London T M Barratt I Murdoch Department of Chemical Pathology, University College and Middlesex School of Medicine and Institute of Urology, London G P Kasidas G A Rose Correspondence to: Dr G P Kasidas, Department of Chemical Pathology, University College and Middlesex School of Medicine, Windeyer Building, Cleveland Street, London WIP 6DP. Accepted 19 October 1990 Primary hyperoxaluria type 1 is an inborn error of glyoxalate metabolism characterised by excessive production and urinary excretion of oxalate and glycolate.' Two thirds of the cases present before the age of 5 years with calcium oxalate urolithiasis, and the disease usually runs a progressive course leading to end stage renal failure with systemic oxalosis before adulthood. It is important to diagnose the condition at an early stage so that therapeutic measures can be implemented to reduce the severity of the disease by modifying the risk factors associated with the deposition of calcium oxalate in the urinary tract and in the tissues. There is, however, a paucity of information in the literature on the urinary excretion rates and plasma concentrations of oxalate and glycolate in young normal children. The report by Gibbs and Watts gives values for urinary oxalate excretion in a few normal children, the youngest of whom was 2 5 years of age,2 and the preliminary report of Kasidas and Rose presented only limited data on children under 1 year of