title: Determination of oxalate excretion in spot urines of healthy children by ion chromatography.
abstract: Evidence for the suitability of spot urines for selective screening in children was obtained by comparing the 24-hour urinary oxalate excretion with the ratio of urinary oxalate to creatinine [mmol/mol] in spontaneously voided urine samples. Spot urines of 169 healthy children aged 1 day to 13 years were analysed in order to establish reference values for the urinary oxalate/creatinine ratio in relation to age and body surface area. Oxalate was measured by automated ion chromatography. Results showed an inverse relationship between the oxalate/creatinine ratio and age. The highest ratios, 131 +/- 57 mmol/mol (mean +/- 2 SD), were found in infants. At age two years, the ratio was 84 +/- 55, at age five years 56 +/- 35, and for children older than ten years 42 +/- 31. This finding can be explained by the gain of muscle mass and hence increased creatinine production with increasing age. Data for the urinary oxalate/creatinine ratio are presented according to body surface area for the assessment of children with abnormal growth. In 19 urine samples from nine patients with primary hyperoxaluria, the oxalate/creatinine ratio greatly exceeded (286-2022 mmol/mol) the above reference ranges. We therefore propose the determination of the oxalate/creatinine ratio in spot urines for the selective screening for hyperoxaluria in children with nephrocalcinosis or urolithiasis.
authors.affiliation: Laboratorium für pädiatrische Nieren- und Stoffwechselkrankheiten, Kinderklinik der Medizinischen Hochschule Hannover, Germany.
authors.forename: C
authors.initials: C
authors.lastname: von Schnakenburg
authors.forename: D J
authors.initials: DJ
authors.lastname: Byrd
authors.forename: K
authors.initials: K
authors.lastname: Latta
authors.forename: G S
authors.initials: GS
authors.lastname: Reusz
authors.forename: D
authors.initials: D
authors.lastname: Graf
authors.forename: J
authors.initials: J
authors.lastname: Brodehl
mesh_terms: D000293:Adolescent; D000375:Aging / Q000652:urine; D001830:Body Surface Area; D002648:Child; D002675:Child, Preschool; D003404:Creatinine / Q000652:urine*; D005260:Female; D006801:Humans; D006959:Hyperoxaluria / Q000175:diagnosis / Q000652:urine; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009397:Nephrocalcinosis / Q000175:diagnosis / Q000652:urine; D010070:Oxalates / Q000652:urine*; D012016:Reference Values; D014545:Urinary Calculi / Q000175:diagnosis / Q000652:urine
chemical_list: D010070:Oxalates; D003404:Creatinine