Estimation of Total Body Sodium by Isotopic Dilution. Ii. Studies on Infants and Children: An Example of a Constant Differential Growth Ratio 12

In contrast to the lack of such information on adults, the literature does contain reports of the direct chemical analysis of a number of fetuses and newborn infants for sodium. Data are available, therefore, with which to compare directly results obtained by the isotopic dilution method. Our study of total body sodium in man, for which data on adults are presented elsewhere (2), was consequently broadened to include infants and children. Since it has been known for some time that the sodium content of the infant, on a per kilogram basis, is higher than that of the adult (3), we set out to investigate the possibility that there was some regularity to the process of chemical growth. That a chemical growth pattern, capable of being expressed in simple mathe- matical terms, does indeed exist, at least with re- gard to sodium accumulation, will be demon- strated by the data to follow.