Evaluate the Effect of Growth Hormone (GH) Treatment on Fibroblast Growth Factor 23, a Known Phosphaturic Agent

Evaluate the Effect of Growth Hormone (GH) Treatment on Fibroblast Growth Factor 23 (a Known Phosphaturic Agent)

The purpose of this study is to evaluate the effect of growth hormone treatment on phosphorus levels in the body. Phosphorus is an important mineral for bone growth. It is well known that growth hormone treatment improves bone density and bone mineral content. The amount of phosphorus is maintained by the kidneys. Fibroblast Growth Factor 23 has recently been recognized to help kidneys control phosphate levels.

This study will compare Fibroblast Growth Factor 23 levels in children with and without growth hormone deficiency. Children with growth hormone deficiency will have levels taken before starting growth hormone replacement and after it has been initiated.

Inclusion Criteria:

• Twenty children with significant short stature < 3rd percentile, ages 3-14 years, and referred to Children's Hospital of Alabama
• Normal healthy volunteer children 3-18 years with normal stature

Exclusion Criteria:

• Patients on medication including GH
• Patients with concomitant hormonal abnormalities
• Patients with disorders of calcium and phosphate metabolism
• Active neoplasms
• Closed epiphysis
• Known bone disorders