Nitrogen balance studies with normal children.

A total of 1148 nitrogen balance studies were conducted in 100 boys and 23 girls 1 to 11 years old. Mixed, customary diets supplied between 8.9 and 21.4% of calories from protein. Duration of balance studies ranged from 72 hr in the youngest subjects to 120 hr in older children. Regressions and 95% confidence intervals of nitrogen retention on nitrogen intake are presented. The slope of the regression was significantly greater for children 12 to 18 months old than for children of other age groups. Correlation coefficients between various parameters of nitrogen balance and energy intake are presented. Although variability in results of nitrogen balances within subjects appears to be rather large, a significant difference between subjects was observed.