correlation is lost perhaps due to the fact that these patients have a lower adipose tissue mass than BMI-matched control individuals [50]. Circulating adiponectin levels in patients with acromegaly are no different from controls [46, 50]. However, obese acromegalic patients have significantly higher adiponectin levels than obese controls [50]. More importantly, acromegalic patients with a lesser degree of adiposity and insulin resistance, as estimated by the visceral adiposity index have significantly higher adiponectin levels than those with a high visceral adiposity index [51]. Control of acromegaly with surgery but not with medical treatment with SSA or pegvisomant tends to increase adiponectin levels [46].
Leptin is another adipocytokine synthesized and secreted by adipose tissue that is crucial in appetite regulation and energy expenditure and its circulating levels positively correlate with body fat mass and waist circumference [52]. Leptin levels in patients with acromegaly are significantly lower than in healthy controls and do not correlate with BMI or waist circumference [50, 53]. Surgical treatment of acromegaly has been shown to result in an increment of leptin levels in some [53] but not all studies [46]. Treatment with SSA but not with pegvisomant also increases leptin levels in patients with acromegaly [46].
Conclusions
Acromegaly is associated with lipid and carbohydrate metabolism abnormalities. Both GH and IGF-1 have a role in increasing insulin resistance and altering glucose and lipid mobilization. The end result is a significant predisposition to glucose intolerance and diabetes and an adverse lipid profile with higher triglyceride and lower HDL levels, as well as the presence of denser and more atherogenic LDL particles. Successful treatment of acromegaly results in significant improvements in this adverse metabolic profile, although a complete normalization of glucose and lipid metabolism is seldom achieved, which likely reflects the co-existence of other risk factors such as the ethnic background of the population and the concomitant presence of hypopituitarism.
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