Reference values of blood components related to fuel metabolism in children after an overnight fast.

The interrelation between blood components, involved in fuel metabolism, and age, sex and glucose was studied in 72 control children (26 girls and 46 boys, aged between 3 and 15 yr) after an overnight fast (14 h). Glucose, lactate, pyruvate, triglycerides and cholesterol are age-independent. Alanine is positively correlated, whereas beta-hydroxybutyrate, acetoacetate and NEFA's are negatively correlated with age. With respect to blood sugar, acetoacetate, NEFA's and cholesterol are glucose-independent. Lactate, pyruvate, alanine and triglycerides are positively correlated with glucose, and beta-hydroxybutyrate--and total ketone bodies--are negatively correlated with glucose. Except for triglycerides, no differences in the concentrations of the above mentioned blood substrates are seen between boys and girls. These data demonstrate that after an overnight fast lipolysis and ketogenesis already are active in young children, probably related to inadequate gluconeogenesis and improvement of carbohydrate regulation with age.