Integrated concentrations of growth hormone, insulin, C-peptide and prolactin in human obesity

Twenty-four hour integrated concentrations of growth hormone (IC-GH) were significantly lower in young, obese subjects than in young subjects who were lean. Significant inverse correlations were found between IC-GH and body mass index (BMI) as well as the IC-GH and the 24 hr integrated concentrations of insulin (IC-I) and C-peptide (IC-C) in obese subjects below 30 yr of age. Since IC-GH decreases with age, the effect of obesity on IC-GH could not be demonstrated in the older subjects; a weak inverse correlation (p < 0.05) between IC-GH and IC-C was found. Prolactin was significantly lower in the older subjects but did not correlate with IC-GH and was similar in lean and obese. Lipid deposition in adipose cells is promoted by high concentrations of insulin as well as low concentrations of growth hormone. We found a significant correlation between the IC-I IC-GH ratio and BMI of both the young and older subjects. Correlations between these two factors do not necessarily imply a cause and effect relationship. It is plausible, however, that the elevated IC-I IC-GH of the obese may facilitate their lipid storage and counter their efforts at weight reduction.