title: Oxalate excretion during the first 7 weeks in very-low-birth-weight infants.
abstract: To determine reference values, we studied urinary excretion of oxalate prospectively and longitudinally in a cohort of 23 very-low-birth-weight (VLBW) infants. The urinary oxalate concentrations were evaluated in 24-hour urine samples by the oxalate oxidase method. Urine samples were obtained at 1, 2-3, 4-5 and 6-7 weeks of age. The median oxalate amount was 24 mumol/kg body weight/day with a 10th-90th percentile range of 16-45 in the 1st week. Oxalate excretion was highest in 2- to 3-week-old infants (median: 35; percentile range: 26-56 mumol/kg body weight/day). In the 4th-5th week, the median was 24 (percentile range: 15-47) mumol/kg body weight/day and in weeks 6-7 also 24 (percentile range: 10-36) mumol/ kg body weight/day. Also, the urinary oxalate concentration as well as the oxalate-creatinine ratio showed increased values in the first 3 weeks of life and decreased values afterwards. In a multivariate analysis, nutrition or gestational age did not affect the urinary oxalate concentration, the daily amount excreted or the oxalate-creatinine ratio. The investigated parameters (oxalate amount and oxalate-creatinine ratio in urine) were significantly age dependent). The data show that urinary oxalate excretion in VLBW infants approaches levels that are in the same range as those of patients with urolithiasis. Thus the risk of nephrocalcinosis in VLBW infants may be increased.
authors.affiliation: Kinderklinik, Christian-Albrechts-Universität Kiel, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Sonntag
authors.forename: J
authors.initials: J
authors.lastname: Schaub
mesh_terms: D017677:Age Distribution; D001724:Birth Weight; D003404:Creatinine / Q000652:urine; D006801:Humans; D007231:Infant, Newborn; D019102:Infant, Very Low Birth Weight / Q000652:urine*; D008137:Longitudinal Studies; D010070:Oxalates / Q000652:urine*; D012016:Reference Values
chemical_list: D010070:Oxalates; D003404:Creatinine