Patients will take estradiol orally for 2 days, to help avoid false results of growth hormone (GH) levels in blood samples. Then provocation testing is done, with two tests back to back. It determines blood levels of GH and the body's response to testing with drugs called arginine and clonidine. Patients are admitted to the pediatric inpatient unit and will have an intravenous (IV) line placed in the arm. Arginine is given by IV over 30 minutes, and blood samples are taken. Right after arginine testing, the clonidine tablet is given. The IGF-1 generation test is then done to see if the body makes IGF-1 as a product in response to injections of GH for 5 consecutive days. This test does not require that patients are inpatients, but after Day 8, patients must be admitted to the pediatric unit to have blood sampling, start Increlex injections, and start close monitoring of blood sugar levels. They will learn how to do a self-injection and follow other advice. They will complete records about the injection site, symptoms, and side effects-keeping records for at least the first 2 days after going home, with each dose change, and as needed. Patients stick their fingertip and place a small drop of blood on a blood sugar monitoring strip. The strip is put into a glucometer-a small hand-held device to measure the blood sugar level. Patients will be instructed to always have a source of sugar available in case blood sugar is too low.