Hormonal Responses to a Short Daytime Fast in Children With Beta-Oxidation Disorders.

Fasting-induced cellular energy deficiency and hypoglycemia are well-known complications of beta-oxidation disorders. The changes in energy homeostasis during fasting are under hormonal regulation. This aspect of fasting metabolism in beta-oxidation disorders is not fully characterized. This clinical study investigates hormonal and substrate profiles during fasting and after a standardized meal in patients with beta-oxidation disorders compared with age-matched healthy controls. Children with beta-oxidation disorders (4 LCHADD, 5 VLCADD, 6 MCADD, median age 8.5, 3-13 years) and healthy age-matched controls (n = 12, median age 9.5, 5-13 years) were subjected to a 4-h daytime fast. Blood samples for glucose, ketones, amino acids, nonesterified fatty acids (NEFA), acylcarnitines, and a panel of metabolically active hormones were analyzed after a 4-h fast and 60 min after intake of the standardized meal. Patients with a beta-oxidation disorder displayed a normal glycemic response to fasting. Most hormonal changes were similar to the changes observed in controls. However, children with LCHADD had higher insulin levels and BMI but, interestingly, relatively low HbA1c compared to children with VLCADD and MCADD. Our findings regarding a possible increased risk of insulin resistance in patients with LCHADD need to be verified in larger cohorts.