Abstract
Measurements of total exchangeable Na were made in a series of 21 infants and children by the isotopic dilution method using Na24. In young infants the results compared very favorably with those obtained by previous workers with carcass analysis. Total body Na was highest in the young infant, averaging 70 meq./kg., and declined gradually during growth toward the adult value of approx. 42 meq./kg. Log-log plots reveal that total body Na is characterized by the regression equation:total Na,meq. = 0.281 body wt., in g. 0.829, thus allowing values for total body Na to be predicted for any given body weight and mineral retentions due to normal growth to be anticipated.
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