Efficacy Study of Recombinant Growth Hormone on Muscle Function in Children Long-term Treated With Glucocorticoid

Children suffering from chronic disease and receiving long-term glucocorticoid therapy suffer over years from severe growth retardation and profoundly altered body composition. They consist in a marked increase in fat mass and a decrease in lean body mass. Published studies have shown that Growth Hormone (GH) treatment in children with Juvenile Idiopathic Arthritis can improve body composition by increasing lean mass and by preventing increase in fat mass. The aim of the present protocol is to evaluate whether the increase in lean body mass observed during GH treatment is associated with changes in muscle strength and mass. In order to be able to evaluate the effect of GH on the muscle a comparative group is needed. Therefore it will be proposed to delay in a group of patients the start of Growth Hormone(GH) treatment by 6 months. As most publications have shown a maximum effect of GH within the first year of treatment, six months should be enough to evaluate short-term effect of GH on the muscle. Therefore, this study will be a randomized trial: immediate start of Growth Hormone (GH) treatment versus start of Growth Hormone treatment 6 months later. After 6 months all children will be treated with GH. Therefore, the follow-up will be one year after baseline.