HGH

Human growth hormone (HGH), known technically as somatotropin, is a single-chain peptide hormone made up of 191 amino acids and secreted by specialized somatotroph cells in the anterior lobe of the pituitary gland ^[1]. It belongs to a family of hormones that promote growth, cell division, and tissue repair. In the body it circulates in pulses, with the largest surge typically occurring roughly an hour after the onset of sleep.

The release of growth hormone is governed by the hypothalamus through two opposing signals: growth-hormone-releasing hormone, which stimulates secretion, and somatostatin, which suppresses it ^[1]. The stomach-derived peptide ghrelin also promotes release, and factors such as exercise, deep sleep, and fasting raise secretion, while high blood glucose and negative feedback from circulating growth hormone and IGF-1 lower it ^[1]. This layered control keeps the hormone within a tightly regulated range.

Physiologically, growth hormone stimulates linear bone growth during childhood and adolescence and continues to shape body composition and metabolism in adults ^[1]. Many of its growth-promoting actions are indirect, carried out through IGF-1, which the hormone induces the liver and other tissues to produce ^[1]. Growth hormone also raises blood glucose and free fatty acids, encourages the breakdown of stored fat, and supports protein synthesis and lean tissue ^[1].

For much of the twentieth century, growth hormone for medical use was extracted from the pituitary glands of human cadavers, a practice halted after some recipients developed Creutzfeldt-Jakob disease. Recombinant DNA technology allowed the hormone to be manufactured biosynthetically, and recombinant human growth hormone, marketed under the generic name somatropin, was approved in the United States in 1985 ^[3]. It is now sold under numerous brand names.

Approved medical uses center on genuine growth hormone deficiency in both children and adults, along with several other conditions such as Turner syndrome, Prader-Willi syndrome, chronic kidney disease in children, and wasting associated with HIV/AIDS ^[1]. Clinical guidelines note that treating adult deficiency can improve body composition, bone strength, exercise capacity, and quality of life, with the greatest benefit in those most severely affected ^[1]. Excess growth hormone, usually from a pituitary tumor, causes acromegaly in adults and gigantism in children, while deficiency in childhood leads to short stature.

Growth hormone has attracted controversial non-medical use. An influential small study in 1990 reported gains in lean mass and bone density in older men given the hormone, fueling anti-aging claims ^[2]. A later systematic review of healthy elderly people concluded that treatment produced only modest shifts in body composition, brought more side effects, and could not be recommended as an anti-aging therapy ^[3]. In sport, growth hormone is a prohibited substance for its presumed anabolic effect, and specialized blood tests have been developed to detect its use despite the difficulty posed by its natural pulsatile secretion ^[4]. It is a prescription-only medicine, and its distribution for non-approved purposes is restricted by law in the United States.

HGH (recombinant human growth hormone) commonly causes fluid retention with swelling, joint and muscle pain, carpal tunnel symptoms, and reduced insulin sensitivity that can raise blood glucose and precipitate diabetes. Higher or prolonged excess produces acromegaly-like tissue overgrowth, and there are concerns about promoting the growth of existing tumors, so it is contraindicated in active malignancy and acute critical illness. It is a potent hormone that should not be treated as a benign supplement.

Somatropin labeling documents several established interactions rooted in its effects on glucose and hepatic enzymes. It antagonizes insulin action and can raise blood glucose, so doses of insulin and oral antidiabetic drugs frequently need upward adjustment. Glucocorticoids at supraphysiologic doses blunt the growth-promoting effect of growth hormone, and conversely growth hormone can increase the clearance of cortisol by inducing 11-beta-hydroxysteroid dehydrogenase, unmasking central hypoadrenalism in at-risk patients. Growth hormone influences cytochrome P450 activity and may alter clearance of CYP-metabolized drugs such as sex steroids, corticosteroids, anticonvulsants, and cyclosporine; oral estrogen in particular reduces the IGF-1 response, so higher somatropin doses may be required. This is research information, not medical advice.

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Human growth hormone was isolated from the human pituitary gland in the mid-1950s, and in 1958 the Boston physician Maurice Raben first treated a growth-hormone-deficient child using hormone extracted from human cadaver pituitaries. For nearly three decades this cadaver-derived hormone was the only supply, distributed through national programs to treat childhood growth failure. That era ended abruptly in 1985, when several recipients developed Creutzfeldt-Jakob disease traced to prion contamination of the pituitary extracts, prompting withdrawal of cadaver-sourced hormone.

In the same year the U.S. Food and Drug Administration approved the first recombinant human growth hormone, produced by Genentech through genetic engineering, providing a safe and essentially unlimited supply. Recombinant somatropin, a 191-amino-acid replica of the natural hormone, has since become standard therapy for growth hormone deficiency and several other approved conditions.

Human growth hormone holds a well-earned place in medicine as a genuine hormone-replacement therapy, transforming the outlook for children and adults with true growth hormone deficiency. Acting largely by prompting the liver to produce insulin-like growth factor 1, it drives skeletal growth in childhood and, in deficient adults, improves body composition by promoting lean tissue and fat breakdown. The switch to recombinant somatropin in 1985 gave clinicians a safe, consistent, and abundant supply, and its approved uses now extend to several conditions beyond classic deficiency.

Because IGF-1 stays elevated far longer than the brief pulses of growth hormone itself, it serves as a convenient marker of overall activity. Candor requires acknowledging that outside of genuine deficiency its use for anti-aging or athletic enhancement is not supported and carries real risks, including reduced insulin sensitivity; within its legitimate medical indications, however, it is a well-validated and valuable therapy.