Corticosteroids Increase Protein Breakdown and Loss in Newly Diagnosed Pediatric Crohn Disease

Children with Crohn disease have altered growth and body composition. Previous studies have demonstrated decreased protein breakdown after either corticosteroid or anti-TNF-alpha therapy. The aim of this study was to evaluate whole body protein metabolism during corticosteroid therapy in children with newly diagnosed Crohn disease. Children with suspected Crohn disease and children with abdominal symptoms not consistent with Crohn disease underwent outpatient metabolic assessment. Patients diagnosed with Crohn disease and prescribed corticosteroid therapy returned in 2 wk for repeat metabolic assessment. Using the stable isotopes [d5] phenylalanine, [1-(13)C] leucine, and [(15)N(2)] urea, protein kinetics were determined in the fasting state. Thirty-one children (18 controls and 13 newly diagnosed with Crohn disease) completed the study. There were no significant differences in protein breakdown or loss between patients with Crohn disease at diagnosis and controls. After corticosteroid therapy in patients with Crohn disease, the rates of appearance of phenylalanine (32%) and leucine (26%) increased significantly, reflecting increased protein breakdown, and the rate of appearance of urea also increased significantly (273%), reflecting increased protein loss. Whole body protein breakdown and loss increased significantly after 2 wk of corticosteroid therapy in children with newly diagnosed Crohn disease, which may have profound effects on body composition. (Pediatr Res 70: 484-488, 2011)