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The clinical conditions associated with GH excess and GH deficiency (GHD) are known to be associated with an increased risk for the cardiovascular morbidity and mortality, suggesting that either an excess or a deficiency in GH and/or IGF-I is deleterious for cardiovascular system. In patients with acromegaly, chronic GH and IGF-I excess commonly causes a specific cardiomyopathy characterized by a concentric cardiac hypertrophy associated with diastolic dysfunction and, in later stages, with systolic dysfunction ending in heart failure if GH/IGF-I excess is not controlled. Abnormalities of cardiac rhythm and anomalies of cardiac valves can also occur. Moreover, the increased prevalence of cardiovascular risk factors, such as hypertension, diabetes mellitus, and insulin resistance, as well as dyslipidemia, confer an increased risk for vascular atherosclerosis. Successful control of the disease is accompanied by a decrease of the cardiac mass and improvement of cardiac function and an improvement in cardiovascular risk factors. In patients with hypopituitarism, GHD has been considered the under- lying factor of the increased mortality when appropriate standard replacement of the pituitary hormones deficiencies is given. Either childhood-onset or adulthood-onset GHD are characterized by a cluster of abnormalities associated with an increased cardiovascular risk, including altered body composition, unfavorable lipid profile, insulin resistance, endothelial dysfunction and vascular atherosclerosis, a decrease in cardiac mass together with an impairment of systolic function mainly after exercise. Treatment with recombinant GH in patients with GHD is followed by an improvement of the cardiovascular risk factors and an increase in cardiac mass together with an improvement in cardiac performance. In conclusion, acromegaly and GHD are associated with an increased risk for cardiovascular morbidity and mortality, but the control of GH/IGF-I secretion reverses cardiovascular abnormalities and restores the normal life expectancy.

Obesity is characterized by abnormal GH secretion, with GH levels reduced up to levels that are comparable to those found in adult patients with organic GH deficiency (GHD). Despite the marked GH insufficiency, obese patients with no evidence of pituitary disease have generally normal levels of total IGF-I but increased levels of free IGF-I. Although the mechanism of the low GH in obesity is not completely understood nor is it clear whether its relationship with visceral adiposity is causal, it is widely accepted that the low GH secretory state in obesity is reversible since it is completely reversed by the normalization of body weight. Since overweight and obesity might affect the GH response to all provocative stimuli, particular attention has been recently paid to the confounding effect of body weight on the interpretation of GH stimulating tests and appropriate cut-offs for lean, overweight, and obese subjects must be used in order to avoid false-positive diagnoses of severe GHD in obese adults. As the definition of appropriate criteria for the correct diagnosis of GHD in obesity is still debated, and the beneficial effects of chronic recombinant human GH replacement on obese individuals have not been definitely proved yet, further studies are therefore mandatory to confirm the real effectiveness of GH supplementation in conditions associated with a blunted GH secretion without organic hypopituitarism and to understand the physiological relevance of "functional" GHD on the pathogenesis of the multiple maladaptative endocrine changes involved in the pathogenesis of obesity.

GH deficiency (GHD) in adults is accompanied by reduced bone mass that may revert only after 2 yr of GH replacement. However, it is unclear whether the gender may modify bone responsiveness to GH replacement in adults. In this study we have evaluated whether bone mineral density (BMD) and turnover improve after GH replacement according to patients' gender. BMD at lumbar spine (LS) and femoral neck (FN), serum osteocalcin (OC), and urinary cross-linked N-telopeptides of type I collagen (Ntx) were assessed in 64 hypopituitaric patients (35 men, 30-50 yr) before and 2 yr after the beginning of GH replacement. Values of IGF-I and BMD at LS and at FN were expressed as Zscores. At study entry, IGF-I and BMD resulted similar among men and women with GHD. During GH replacement, IGF-I levels increased in both men and women without any difference in the percentage of IGF-I increase between the genders (p=0.47). In women receiving estrogen replacement, however, the percentage of IGF-I increase (p<0.05), and the Z IGF-I score (p<0.001) were significant lower than estrogen untreated women, although IGF-I levels were similar in the 2 groups (p=0.53). The GH dose adjusted for body weight required to restore normal age- and sex- matched IGF-I levels was lower in men than in women (p<0.001), and was higher in women receiving than in those not receiving estrogen replacement (p<0.05). In contrast, hypogonadal men treated with testosterone and eugonadal men received a similar GH dose (p=0.97). Also OC, Ntx levels, lumbar and femoral BMD improved (p<0.001) in all patients. Nevertheless, a greater increase in lumbar BMD increase was observed in men than in women (8.0+/-2.1 vs 2.6+/-0.4%; p<0.05). No significant difference was revealed in bone parameters in women treated or untreated with estrogen replacement and in men treated or not with testosterone replacement for concomitant hypogonadism. At the multiple correlation analysis, gender was a stronger predictor for the required GH dose than the age (p<0.001 and p=0.02, respectively). In conclusion, a 2-yr GH replacement normalizes IGF-I levels, increases bone mass and improves bone turnover both in men and in women with GHD without any difference between the 2 groups, provided that the dose of GH was modulated on the basis of IGF-I levels. Women receiving oral estrogens should receive a GH dose approximately doubled, as compared to men and women not receiving oral estrogens, to achieve similar effects on bone density and turnover. In particular, GH replacement dose, to be successful on bone mass and turnover, depends on gender in hypopituitary patients aged below 50 yr.

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.

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.