title: Developmental changes of oxalate excretion in enterally fed preterm infants.
abstract: To further substantiate gestational age-related changes in oxalate excretion, we studied urinary oxalate excretion in 66 preterm infants born at 23.4-34.7 weeks of gestation. Spot urine of 66 preterm infants was analysed by ion chromatography as soon as they were completely orally fed with enriched breast milk and/or special preterm milk formula (days 7 to 57 of postnatal life). Infants with evidence of renal, gastrointestinal, muscular or metabolic disease were not included. Newborns on parenteral nutrition were excluded. Oxalate/creatinine ratios (Ox/Cr) decreased with gestational age (three age groups: group 1, 23 0/7-28 0/7; group 2, 28 1/7-32 0/7; and group 3, 32 1/7-35 0/7 weeks of gestation). The mean Ox/Cr was highest in group 1 (398.2 mmol/mol +/- 116.8; n = 21). Differences between groups 1 + 3 were statistically significant; p = 0.001; those between groups 1 + 2 and between groups 2 + 3 were not. Ox/Cr correlated inversely with gestational and maturational age (r = -0.41, p = 0.001; r = -0.33, p = 0.007) and positively with postnatal age (r = 0.32, p = 0.008). It correlated inversely with birth weight as well as actual weight at sample collection (r = -0.46 and -0.44, p < 0.001). Ox/Cr was significantly linked to energy and carbohydrate intake (r = 0.3 and 0.4, p = 0.03 and 0.001). These results were independent of sex. In the present study we show that urinary oxalate excretion in preterm infants depends on gestational age.
authors.affiliation: Department of Paediatric Kidney-, Liver- and Metabolic Diseases, Children's Hospital, Hannover Medical School, Hannover, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Illsinger
authors.forename: T
authors.initials: T
authors.lastname: Lücke
authors.forename: B
authors.initials: B
authors.lastname: Vaske
authors.forename: K-H
authors.initials: KH
authors.lastname: Schmidt
authors.forename: B
authors.initials: B
authors.lastname: Bohnhorst
authors.forename: A M
authors.initials: AM
authors.lastname: Das
mesh_terms: D002657:Child Development / Q000502:physiology*; D015331:Cohort Studies; D003404:Creatinine / Q000652:urine; D002149:Energy Intake / Q000502:physiology; D004750:Enteral Nutrition; D005260:Female; D005865:Gestational Age; D006801:Humans; D007228:Infant Nutrition Disorders / Q000628:therapy*; D007227:Infant Nutritional Physiological Phenomena; D007231:Infant, Newborn; D007234:Infant, Premature / Q000254:growth & development / Q000502:physiology / Q000652:urine*; D008297:Male; D019815:Oxalic Acid / Q000652:urine*; D013997:Time Factors
chemical_list: D019815:Oxalic Acid; D003404:Creatinine