Technische Universität München

The Entrepreneurial University

hGH and IGF-1
The long-term risks of high doses GH abuse are not well known. Patients who have acromegaly with chronic endogenous hGH excess (consequence of somatotroph pituitary adenoma) may be the most accurate model for an athlete who supplements an already normal hormone level. hGH is a diabetogenic hormone. High doses of hGH increase insulin resistance in athletes and glucose intolerance or diabetes mellitus develop significantly more often in healthy aged men after GH treatment than in controls. Exposure to chronic GH excess in the pathophysiological model of acromegaly leads to insulin resistance, impaired glucose tolerance, and clinically overt diabetes mellitus. Administration of high doses hGH to athletes increases free T3 into supraphysiological range and reduces free T4 due to increased extrathyroidal conversion of T4 to T3. The long term effect on thyroid function in athletes is unclear, but hGH and IGF-1 excess cause thyroid overgrowth and nodular or diffuse goiter, which are common phenomenon in acromegaly. Other consequences of chronic GH excess are hyperparathyroidism and increased risk of neoplastic complications. The impairment of gonadal function is a common clinical finding of acromegaly in both sexes, but its pathogenesis remains unclear. Recent data suggest that elevated hGH levels per se are responsible for the high prevalence of signs of hyperandrogenism in women with chronic GH excess, which, in turn, may lead to menstrual abnormalities. Men with acromegaly have prostate enlargement with a high prevalence of prostate abnormalities.
Administration of hCG may result in ovarian hyperstimulation syndrome in women and may induce gynaecomastia in men. Data show that concomitant abuse of AAS and hCG cause impairment on semen quality, although it seems that sperm count could be maintained with this regimen. A significant positive correlation has been found between the hCG dose during the AAS cycle and the relative amount of morphologically abnormal spermatozoa. 
Insulin lowers blood glucose concentrations through inhibiting hepatic glucose production and through accelerating glucose uptake. Physical exercise increases the insulin sensitivity of the skeletal muscles by causing an insulin-independent increase in the number of the glucose transporters in cell membranes. Therefore the abuse of insulin by athletes may result in hypoglycaemia. In addition exercise can precipitate hypoglycaemia because absorption of injected insulin is more rapid during exercise. Unless treated promptly hypoglycaemia may result in coma and death.
The increasing levels of ACTH caused by ACTH misuse may mimic excess hormone secretion observed in patients with some pituitary tumours resulting in ACTH-dependent Cushing’s syndrome (Cushing’s disease). Besides the other signs of the Cushing’s syndrome, the level of the weak mineralcorticoid deoxycorticosterone may be elevated by ACTH leading to salt and water retention. The secretion of adrenal androgens will be also elevated and may result in hirsutism and acne in women.