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Influence of nutrition on urinary oxalate and calcium in preterm and term infants
Insights
Urinary oxalate and calcium excretion differs between preterm and term infants. Excretion levels are influenced by infant age and feeding type (formula vs. human milk).
Area of Science:
- Neonatal Nutrition
- Pediatric Nephrology
- Infant Metabolism
Background:
- Limited data exists on normal urinary oxalate (Ox) and calcium (Ca) excretion in infants.
- Gestational age and nutritional factors significantly impact infant development and metabolism.
- Understanding these factors is crucial for assessing infant health and development.
Purpose of the Study:
- To determine normal urinary Ox and Ca excretion in preterm and term infants.
- To investigate the influence of gestational age and nutritional intake (formula vs. human milk) on urinary Ox and Ca levels.
- To establish reference ranges for urinary Ox/creatinine (Cr) and Ca/Cr ratios in early infancy.
Main Methods:
- Analysis of spot urine samples from 64 preterm and 37 term infants (1-60 days old).
- Measurement of urinary oxalate, calcium, and creatinine concentrations.
- Calculation of molar Ox/Cr and Ca/Cr ratios, stratified by gestational age and feeding type (formula or human milk).
Main Results:
- Preterm infants exhibited higher urinary Ox/Cr ratios than term infants, regardless of feeding type.
- Urinary Ox/Cr ratios increased during the first two months of life in all infants.
- Urinary Ca/Cr ratios were similar in the first month but increased by the second month, with the highest levels in preterm infants fed human milk.
Conclusions:
- Urinary oxalate and calcium excretion in infants are significantly influenced by both gestational age and nutrient intake.
- These findings highlight the importance of considering feeding type and prematurity when evaluating urinary Ox and Ca levels in infants.
- Further research is warranted to establish precise reference ranges and understand long-term implications.
Abstract:
Few data for normal urinary oxalate (Ox) and calcium (Ca) excretion related both to gestational age and nutritional factors have been reported in preterm or term infants. We therefore determined the molar Ox and Ca to creatinine (Cr) ratios in spot urines from 64 preterm and 37 term infants aged 1-60 days, either fed formula or human milk (HM). Only vitamin D was supplemented; renal or metabolic diseases were excluded. Urinary Ox/Cr ratio was higher in preterm than in term infants, both when formula fed (1st month 253 vs. 180 mmol/mol and 2nd month 306 vs. 212 mmol/mol; P<0.05) or HM fed (206 vs. 169 mmol/ mol and 283* vs. 232 mmol/mol; *P<0.05). Ox/Cr was also higher in formula- than HM-fed preterm infants. The ratio increased during the first 2 months of life irrespective of nutrition. Urinary Ca/Cr ratio was comparable in all groups during the 1st month of life, except for a lower (P < 0.05) value in term infants fed HM (0.10 mol/mol). It increased in all groups during the 2nd month of life, being highest in HM-fed preterm infants (1.86 mol/mol). In conclusion, urinary Ox and Ca excretion is influenced by both gestational age and nutrient intake in preterm and term infants.