Background: Obesity is associated with a relative deficiency of growth hormone, which is predictive of greater visceral fat and markers of cardiovascular risk. The study's purpose was to use recombinant human growth hormone (rhGH) as a physiologic probe to assess the effects of reversing obesity-related GH deficiency on body composition, cardiovascular risk markers, and insulin resistance.
Methods: 22 obese girls 13-21 years old were followed for a randomized 6-month trial of rhGH vs. placebo/no treatment. At baseline and 6-months, DXA was performed for body composition, MRI to measure visceral, subcutaneous and total adipose tissue (VAT, SAT and TAT), and fasting blood drawn for IGF-1, inflammatory cardiovascular risk markers [soluble intercellular adhesion molecule (sICAM), high sensitivity CRP], lipids and HbA1C. An oral glucose tolerance test (OGTT) was performed. Twelve girls completed the 6-month visit. Baseline and mean 6-month change were compared between the groups using the Student t-test and the relationship between variables was determined through multiple regression analysis.
Results: After 6-months, the rhGH group maintained IGF-1 levels, and had decreases in total cholesterol (p = 0.03), sICAM-1 (p = 0.04) and HbA1C (p = 0.03) compared to placebo/no treatment. The rhGH group trended towards greater decreases in LDL and 2-hour OGTT glucose. Glucose tolerance did not worsen with rhGH administration.
Conclusions: Administering rhGH in small doses is able to stabilize IGF-1 levels in obesity. We have also shown that rhGH administration leads to an improvement in some markers of cardiovacular risk with without adversely affecting glucose tolerance.
Clinical trial registration number: NCT01169103.
Keywords: Adolescents; Body composition; Females; Growth hormone; Inflammatory markers; Visceral fat.