Background: In spite of the increasing information that has recently been accumulated on the involvement of ghrelin and leptin in the control of energy balance, the relationship between ghrelin and leptin and the growth hormone (GH)-insulin-like growth factor 1 (IGF-1) axis in the pathological condition characterized by GH deficiency has been poorly clarified. Therefore, we performed this study to examine the correlation of the plasma levels of ghrelin and leptin with the anthropometric and biochemical markers in GH-deficient (GHD) adults as compared to their healthy cohorts.
Methods: In 60 male adults (GHD; n = 12, healthy control; n = 48, average age: 54 years), we investigated the correlations between the serum leptin and ghrelin levels with the anthropometric and biochemical factors in the control group, as compared to the GHD patients. The diagnosis of GH deficiency was made when peak response for serum GH was <5 microg/L to a GH-provocative test (L-dopa test). All subjects underwent assessment of waist circumference, body mass index (BMI) and percentage body fat for their body composition. Plasma ghrelin, leptin, insulin, GH and IGF-1 were measured.
Results: Groups were matched for age, BMI, waist circumference and percent of body fat. Ghrelin and leptin levels were not significantly different between the two groups. There was no correlation between the peak GH level or the GHAUC and the ghrelin concentrations in the GHD subjects. Plasma leptin correlated positively with percentage of body fat, total cholesterol and LDL-cholesterol, but it had no correlation with the peak GH or area under the curve for growth hormone (GHAUC) in the GHD subjects. Plasma ghrelin concentrations were not correlated with the biochemical and anthropometric markers in the subjects with GHD, and ghrelin showed no significant differences in the GHD and control subjects. Leptin concentrations were positively correlated with body fat, but they were not correlated with the levels of either IGF-1 or GH in the GHD patients.
Conclusions: It is possible that ghrelin concentrations appeared normal in the GHD subjects because of the opposing influences of increased adiposity, which reduce ghrelin secretion, and GHD, which may increase it. Further studies are needed to clarify these controversies about the relation of ghrelin and leptin with the GH and IGF-1 levels.