METABOLIC BALANCE STUDIES IN PREMATURE-INFANTS

Over the past decades metabolic balance studies have been extensively used for the purpose of determining the retention rates of nutrients i ngested by neonates. Traditionally, data derived from these studies ha ve been used to estimate nutritional requirements in both full-term an d premature infants. This article provides a historical review of the methodology used in classic metabolic balance studies performed in neo nates since 1955. In addition, descriptions of new methodologies that improve the reliability and reproducibility of metabolic balance studi es conducted in premature infants that include: (1) the recognition th at an acclimation period of steady and sufficient energy intake is nec essary prior to the initiation of the balance study; (2) the use of a minimum period of 72 hows for the total duration of balance study; and (3) the use of stool markers to time the period. Also described in th is article are the retention rates of calcium and fat that were measur ed in premature infants by means of metabolic balance studies conducte d with the use of recommended methodology.