ABSTRACT
Blood ketone, blood glucose and plasma NEFA concentrations after a 24 hour fast werre studied in 181 infants and children from birth to 12 years of age. The same measurements following epinephrine injections were made in 89 infants and children from birth to 14 years. It was found that infants under 36 hours were more resistant to ketosis on fasting than infants 2 to 6 days of age whose ketosis became almost as severe as that of subjects aged 1 week to 4 years. The difference in response between these two newborn groups was found to be associated with large stores of liver glycogen in the younger group. Infants under 36 hours did not appear to have any impairment of fat catabolism as indicated by a progressive rise in blood ketone levels on more extended fasts and by their normal NEFA elevation after epinephrine. Subjects 1 week to 4 years of age developed more ketosis on fasting than did older children. It was shown that this was not related to differences in excretion or utilization of ketone bodies, indicating that variation in ketone production was the factor responsible. Blood sugar levels below 40 mg. percent occurred in 45 of 123 subjects under 6 months of age who were fasted for 24 hours. With one exception, blood sugar below this level was not found in subjects over 7 months of age(AU)