Study of Growth Hormone and Bone in Obesity

Obesity is an important risk factor for osteoporosis and fractures. With the growing prevalence of obesity in the U.S., understanding the pathophysiology of bone loss in this population is of importance to public health. Growth hormone (GH) is a critical mediator of bone homeostasis and is markedly reduced in obesity. Our preliminary data suggest an important role for the GH/insulin-like growth factor 1 (IGF-1) system in the pathogenesis of bone loss in obesity. The development of novel imaging techniques provides an opportunity to investigate the effects of GH on skeletal structure and strength, which will provide insights into the pathogenesis of obesity related bone loss. Understanding the pathophysiology of bone loss in obesity may help identify new treatment targets for this important complication. The investigator hypothesizes that low-dose GH administration for 18 months will improve skeletal health.

Growth Hormone is Genotropin, provided by Pfizer Inc. It is self administered daily for 18 months using a 5 mg injection pen device. Dose will be titrated based on IGF-1 levels.

Placebo will be provided by Pfizer Inc. It will appear identical to active growth hormone and will be administered in the same manner.

Inclusion Criteria: Ages 18-65 and generally healthy BMI ≥ 25 kg/m2 Bone mineral density (BMD) T score ≤ -1.0 and > -2.5 (as measured by DXA) Exclusion Criteria: For women: amenorrhea for 3 months, pregnancy or breastfeeding, polycystic ovary syndrome History of diabetes mellitus, cancer or other serious chronic disease Use of osteoporosis medications Anemia