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Randomised controlled trial of postnatal sodium supplementation on body composition in 25 to 30 week gestational age
G Hartnoll1, P Bétrémieux, N Modi
1Section of Paediatrics and Neonatal Medicine, Imperial College School of Medicine, Hammersmith Hospital, London W12 0NN.
Insights
Early sodium supplementation in preterm infants can delay normal postnatal body water loss, impacting body composition. Delayed supplementation until after initial weight loss is recommended for better outcomes.
Area of Science:
- Neonatology
- Pediatric Physiology
- Clinical Nutrition
Background:
- Preterm infants experience significant physiological fluid shifts post-birth.
- Routine sodium supplementation is common in neonatal care.
- The optimal timing for initiating sodium supplementation is not fully established.
Purpose of the Study:
- To compare the effects of early versus delayed sodium supplementation on body composition and water compartments in preterm infants.
- To investigate the impact of supplementation timing on postnatal adaptation during the first two weeks of life.
Main Methods:
- Randomized controlled trial in preterm infants (25-30 weeks gestation).
- Groups received sodium supplementation on day 2 (early) or after 6% birthweight loss (delayed).
- Measured total body water (H(2)(18)O dilution) and extracellular fluid volume (sodium bromide dilution).
Main Results:
- Delayed sodium supplementation led to significant loss of total body water and extracellular fluid in the first week and by day 14.
- Early sodium supplementation attenuated this physiological water loss.
- Body composition was significantly altered by day 7 in the delayed group, with no significant differences by day 14.
Conclusions:
- The timing of sodium supplementation influences body composition and water balance in preterm infants.
- Early supplementation can prevent the normal postnatal loss of body water.
- A tailored approach, potentially delaying supplementation, may be beneficial, especially for infants with respiratory distress syndrome.
Aims:
To compare the effects of early and delayed sodium supplementation on body composition and body water compartments during the first two weeks of postnatal life.
Methods:
Preterm infants of 25-30 weeks' gestation were stratified and randomly assigned according to gender and gestational age, to receive a sodium intake of 4 mmol/kg/day beginning either on the second day after birth or when weight loss of 6% of birthweight had been achieved. Daily sodium intake, total fluid intake, energy intake, urine volume, and urinary sodium excretion were recorded. Total body water was measured by H(2)(18)O dilution on days 1, 7, and 14, and extracellular fluid volume by sodium bromide dilution on days 1 and 14.
Results:
Twenty four infants received early, and 22 delayed, sodium supplementation. There were no significant differences between the groups in body water compartments on day 1. In the delayed group, but not the early group, there was a significant loss of total body water during the first week (delayed -44 ml/kg, p=0. 048; early 6 ml/kg, p=0.970). By day 14 the delayed, but not the early group, also had a significant reduction in extracellular fluid volume (delayed -53 ml/kg, p=0.01; early -37 ml/kg, p=0.2). These changes resulted in a significant alteration in body composition at the end of the first week (total body weight: delayed 791 ml/kg; early 849 ml/kg, p=0.013). By day 14 there were once again no significant differences in body composition between the two groups.
Conclusions:
Body composition after preterm birth is influenced by the timing of introduction of routine sodium supplements. Early sodium supplementation can delay the physiological loss of body water that is part of normal postnatal adaptation. This is likely to be of particular relevance to babies with respiratory distress syndrome. A tailored approach to clinical management, delaying the introduction of routine sodium supplements until there has been postnatal loss of body water, is recommended.