Dynamics of Body Composition and Bone in Patients with Juvenile Idiopathic Arthritis Treated with Growth Hormone

Introduction: GH has a positive impact on growth, bone, and muscle development. The objectives of this study were to demonstrate the effects of GH treatment on regional body composition and bone geometry at final height in patients with juvenile idiopathic arthritis (JIA). Patients and Methods: In this longitudinal study, parameters of bone mineral density and geometry as well as muscle and fat cross-sectional area (CSA) in the nondominant forearm were recorded using peripheral quantitative computed tomography at yearly intervals until final height in 12 patients (seven females) receiving GH treatment. Data at final height were compared with 13 patients (nine females) with JIA not treated with GH. Results: Patients were treated with GH for a mean of 5.35 +/- 0.7 yr. Correcting for height, total bone CSA (+0.89 +/- 0.5 SD) and muscle CSA (+1.14 +/- 0.6 SD) increased significantly and normalized at final height. Compared with JIA patients without GH at final height, there was a significantly higher muscle CSA and a lower fat CSA in GH-treated patients. Additionally, in relation to total bone CSA, there was significantly more cortical and less marrow CSA in boys with GH treatment. Conclusion: During GH treatment, there was a significant increase and normalization of total bone and muscle CSA at final height. In accordance with an anabolic effect of GH, fat mass stabilized at the lower limit of healthy children. At final height, cortical and marrow CSA, relative to total bone CSA, were normalized in GH-treated patients. (J Clin Endocrinol Metab 95: 178-185, 2010)