Beneficial Effects of Growth Hormone on Body Composition and CV Risk Factors in Obese Men

According to the recent results of a double-blind, randomized, placebo-controlled trial, growth hormone (GH) administration in men with visceral obesity may provide beneficial effects on body composition and risk factors for cardiovascular (CV) disease.

Karen Klahr Miller, MD, endocrinologist at Massachusetts General Hospital in Boston, and colleagues released their findings at ENDO 2013: The Endocrine Society’s 95^th Annual Meeting and Expo in San Francisco on June 17, 2013.

According to the researchers, visceral obesity is associated with increased cardiometabolic risk and decreased physiologic GH secretion. GH is involved in the regulation of body composition, insulin resistance, and atherogenesis, as well as cholesterol metabolism in the liver.

Supplementation with growth hormones has been shown to lead to improvement in body composition and reduction in inflammatory CV markers in patients with GH deficiency due to hypopituitarism. Additionally, researchers have previously demonstrated an association between low-dose GH administration and improvements in body composition and CV markers in obese premenopausal women; however, a similar relationship has not been studied in obese men. The aim of this study was to evaluate the effects of GH administration on CV risk and body composition in men with visceral obesity. Outcome measures for body composition included visceral adipose tissue (VAT)/subcutaneous abdominal adipose tissue (SAT) ratio as measured by CT, fat and lean mass as measured by DXA, and intramyocellular (IMCL) and intrahepatic (IHL) lipids as measured by proton MR spectroscopy. CV risk markers included high-sensitivity C-reactive protein (hsCRP), total cholesterol, HDL cholesterol, LDL cholesterol, apolipoprotein B (ApoB), fibrinogen, tissue plasminogen activator (tPA), carotid intimal-medial thickness (IMT), and endothelial function.

Sixty-two obese men with a mean BMI of 37.6 and average age of 33.7 years were randomized to receive daily GH administration or placebo for 6 months. The average GH dose at 6 months was 1.1±0.4 (SEM) mg/day. Measurements were obtained at baseline, 6 weeks, and 6 months.

At the end of the study period, BMI increased in both groups (from 37.0 at baseline to 38.3 at 6 months, p = 0.05) but there was no significant difference in BMI change between groups. Decreases in VAT/SAT ratio (p = 0.02) and trunk to extremity fat ratio (p = 0.009) were seen in the GH group when compared with the placebo group. After controlling for the weight change (as weight changes are known to affect body composition and CV risk markers), significant decreases were also found in liver fat (p = 0.002) and VAT (p = 0.05). This also increased the significance of the VAT/SAT change (p = 0.003). However, an increase in 2-hour glucose in the GH group was noted when compared with placebo (p = 0.04).

In regards to cardiovascular risk markers, hsCRP was decreased in the GH treatment group, both before and after controlling for weight change (p = 0.008 and p = 0.005, respectively). A trend toward decrease in tPA and ApoB was noted in the GH group, but this was not significant (p = 0.1). There was a significant decrease in ApoB/LDL ratio in the patients receiving GH compared with those receiving placebo (p = 0.04).

There were no significant differences between groups in total cholesterol, LDL cholesterol, HDL cholesterol, fibrinogen, lean mass, IMCL, IMT, endothelial function, and fasting glucose.

Elevated glucose parameters led to discontinuation from the study for 4 subjects in the GH treatment group and 1 in the placebo group.

The authors concluded that GH administration in young men with visceral adiposity improves body composition, results in relative improvement in intrahepatic lipids, and demonstrates beneficial effects on CV risk markers hsCRP and apoB/LDL. As these effects may have important implications, further studies are warranted to further examine their mechanisms.

This study was supported by NIH grants. Growth hormone and identical placebo were provided by Genentech. The authors have nothing to disclose.