Growth Hormone and Endothelial Function in Children

The purpose of the research is to learn more about how the lining of arteries in the body (called the endothelium) is affected by growth hormone treatment in children and adolescents. Poor function by the blood vessels is associated with increased risk of heart disease or stroke. This research is being done because growth hormone treatment has been shown to make the endothelium work better in adults. Growth hormone treatment may have the same or different effects in children because the dose is larger in children. Children between 8 and 18 years who are to be started on growth hormone will be eligible to participate. Blood vessel function will be studied before starting growth hormone and 3 months after. This will be done by measuring blood flow to the arm before and after 5 min of stopping blood flow to the arm. The three months of growth hormone will be given free.