M C Savanelli | PubMed Health

PubMed2006

Growth hormone status in morbidly obese subjects and correlation with body composition.

Morbidly obese subjects are characterized by multiple endocrine abnormalities and these are paralleled by unfavorable changes in body composition. In obese individuals, either 24-h spontaneous or stimulated GH secretion is impaired without an organic pituitary disease and the severity of the secretory defect is proportional to the degree of obesity. The GHRH+arginine (GHRH+ARG) test is likely to be the overall test of choice in clinical practice to differentiate GH deficiency (GHD) patients. Similarly to other provocative tests, GHRH+ARG is influenced by obesity per se. Therefore, a new cut-off limit of peak GH response of 4.2 microg/l in obese subjects has been recently assumed. The aim of the present study was to investigate the reciprocal influence between decreased GH secretion and body composition in a group of 110 morbidly obese subjects, using the new cut-off limit of peak GH response to GHRH+ARG test for these subjects. In our study, GHD was identified in 27.3% of the obese subjects, without gender difference. In GDH obese subjects body mass index (BMI), waist circumference, waist-to-hip ratio (WHR), fat mass (FM), and resistance (R) were higher while reactance (Xc), phase angle, body cell mass (BCM), IGF-I, or IGF-I z-scores were lower than in normal responders (p<0.001). In all obese subjects, GH peak levels showed a negative correlation with age, BMI, waist circumference and FM, and a positive correlation with IGF-I. In the stepwise multiple linear regression, waist circumference and FM were the major determinants of GH peak levels and IGF-I. In conclusion, using the new cut-off limit of peak GH response to GHRH+ARG test for obese subjects, about 1/3 morbidly obese subjects were GHD. GHD subjects showed a significantly different body composition compared with normal responders, and the secretory defect was correlated to different anthropometric variables with waist circumference and FM as the major determinants.

Adipose Tissue↗

PubMed2005

Somatopause: dismetabolic and bone effects.

The physiological changes that the human body undergoes during aging are similar to those observed in GH deficiency (GHD). Early changes of aging are represented by increased fat mass, increased cardiovascular risk, reduced muscle mass and strength, reduced exercise tolerance, thinned skin, decreased strength and impaired quality of life. These observations led to hypothesize that the elderly could be GH deficient and would benefit from GH treatment. However, the effects of GH treatment in healthy elderly subjects by randomized and controlled studies are less promising than initially hypothesized. The etiopathology of age-related bone loss is multifactorial including menopause, andropause, somatopause and secondary hyperparathyroidism. GH has multiple effects on bone, either direct or mediated by IGF-I, stimulating osteoblast proliferation as well as osteoclast differentiation. Consequently, decline in GH secretion reduces bone turnover that causes osteopenia in young adults, but it has been hypothesized that it could protect against fractures in elderly subjects. The increase of bone remodeling achieved by GH therapy may be helpful in elderly men and women who have severely decreased bone turnover and impaired osteoblastic function. In conclusion, the endocrine pattern of aging is distinct from the decrease of GH/IGF-I levels associated with hypopituitarism. However, GH plays a role in metabolism and bone physiology throughout the human life span, although there is insufficient evidence for a clear therapeutic role of rhGH in aging. Thus, more data are needed to define the effects of somatopause to identify who could potentially benefit from the effects of somatotropic treatment.

Adult↗