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Protein metabolism and postnatal growth in very low birthweight infants
1Department of Neonatology, CHUV Lausanne, Switzerland.
Insights
New bedside methods quantify growth costs in premature infants. Healthy preemies use 30% of energy for growth, with protein synthesis far exceeding needs.
Area of Science:
- Neonatal physiology
- Pediatric nutrition
- Metabolic research
Background:
- Advancements in bedside investigative methods allow for quantification of abstract physiological concepts in very low birthweight infants.
- Previously abstract concepts like energy cost of growth and protein turnover are now measurable.
- Understanding energy expenditure is crucial for optimizing growth in premature neonates.
Purpose of the Study:
- To quantify key metabolic aspects of growth in very low birthweight infants.
- To investigate the energy cost of growth and protein metabolism in different infant populations.
- To utilize stable isotope techniques for a deeper understanding of protein accretion.
Main Methods:
- Application of new bedside investigative methods.
- Utilisation of stable isotope techniques with 15N- or 13C-labeled amino acids.
- Measurement of energy cost of growth, protein gain efficiency, metabolic cost of protein gain, and protein turnover.
Main Results:
- 'Healthy' premature infants allocate approximately 30% of their energy expenditure to the metabolic cost of growth.
- Protein synthesis rates (10-12 g/kg/day) significantly exceed the rate required for net protein gain (2 g/kg/day).
- Distinct characteristics in postnatal growth and protein metabolism were observed between 'healthy', 'sick', and 'intrauterine undernourished' infants.
Conclusions:
- Bedside investigative methods have successfully quantified complex physiological concepts related to growth in very low birthweight infants.
- Protein accretion is a highly energy-demanding process in growing tissues, with synthesis rates substantially higher than net gain.
- Postnatal growth and protein metabolism exhibit significant variability based on the infant's health status and intrauterine nutritional history.
Abstract:
Due to the development of new 'bedside' investigative methods, relatively abstract physiologic concepts such as energy cost of growth, efficiency of protein gain, metabolic cost of protein gain and protein turnover have been quantified in very low birthweight infants. 'Healthy' premature infants expend about 30% of their energy to cover the metabolic cost of growth. Stable isotope techniques using 15N-(or 13C)-labeled amino acids gave a new insight into this very high energy demanding process represented by the protein accretion in growing tissues. It has been demonstrated that the rate of protein synthesis (10-12 g/kg/day) greatly exceeds that necessary for net protein gain (2 g/kg/day). The postnatal growth and protein metabolism have different characteristics in 'healthy', 'sick' or 'intrauterine undernourished' very low birthweight infants.