Prevalence and Metabolic Consequences of Relative Growth Hormone Deficiency in Abdominal Obesity

Obesity is associated with significant morbidity and mortality and is a primary public health concern. Both the incidence and prevalence of obesity have increased over the last several decades, with obesity now affecting an estimated 31% of the American population. Recent data suggest that people with abdominal obesity commonly exhibit low levels of GH, which affects the body's growth rate and the way the body uses food for energy. Low GH levels and excess abdominal fat have been linked to improper functioning of the cardiovascular system and, therefore, may increase one's risk of cardiovascular disease. This study will determine the prevalence of GH deficiency in abdominal obesity and whether GH deficiency is associated with increased cardiovascular risk beyond traditional risk factors.

Participation in this observational study will last between 2 and 4 weeks. The study will consist of two outpatient visits, held at either the Massachusetts General Hospital or Massachusetts Institute of Technology. Visit 1 will last 4 hours and will include a physical exam, medical history, blood draw, urine sampling, indirect calorimetry test, and growth hormone releasing hormone (GHRH)+Arginine stimulation test. Eligible participants will return within the next 3 weeks for Visit 2, which will last 5 hours. Before the second visit, participants will be asked to record their food intake for 4 days on a food record. During the visit, participants will have a repeat physical exam, urine sampling, and blood draw. Participants will also undergo an oral glucose tolerance test, whole body DEXA scan, abdominal computed tomography (CT) scan, and a carotid ultrasound. Participation in the study will end after Visit 2.