Growth hormone (GH) or somatotropin, also known as human growth hormone in its human form, is a peptide hormone that stimulates growth, cell reproduction, and cell regeneration in humans and other animals. It is thus important in human development. GH also stimulates production of Insulin-like growth factor 1 (IGF-1) and increases the concentration of glucose and free fatty acids. It is a type of mitogen which is specific only to the receptors on certain types of cells. GH is a 191-amino acid, single-chain polypeptide that is synthesized, stored and secreted by somatotropic cells within the lateral wings of the anterior pituitary gland.
Gigantism, also known as giantism, is a condition characterized by excessive growth and height significantly above average. In humans, this condition is caused by over-production of growth hormone in childhood.
Growth hormone deficiency (GHD), or human growth hormone deficiency, is a medical condition resulting from not enough growth hormone (GH). Generally the most noticeable symptom is that an individual attains a short height. Newborns may also present low blood sugar or a small penis size. In adults there may be decreased muscle mass, high cholesterol levels, or poor bone density.
Growth hormone therapy refers to the use of growth hormone (GH) as a prescription medication—it is one form of hormone therapy. Growth hormone is a peptide hormone secreted by the pituitary gland that stimulates growth and cell reproduction. In the past, growth hormone was extracted from human pituitary glands. Growth hormone is now produced by recombinant DNA technology and is prescribed for a variety of reasons. GH therapy has been a focus of social and ethical controversies for 50 years.
Insulin-like growth factor 1 (IGF-1), also called somatomedin C, is a hormone similar in molecular structure to insulin which plays an important role in childhood growth, and has anabolic effects in adults.
Congenital adrenal hyperplasia due to 17α-hydroxylase deficiency is an uncommon form of congenital adrenal hyperplasia (CAH) resulting from a mutation in the gene CYP17A1, which produces the enzyme 17α-hydroxylase. It causes decreased synthesis of cortisol and sex hormones, with resulting increase in mineralocorticoid production. Thus, common symptoms include mild cortisol deficiency, ambiguous genitalia in men or amenorrhea at puberty in women, and hypokalemic hypertension. However, partial (incomplete) deficiency often has inconsistent symptoms between patients, and affected women may be asymptomatic except for infertility.
Hypopituitarism is the decreased (hypo) secretion of one or more of the eight hormones normally produced by the pituitary gland at the base of the brain. If there is decreased secretion of one specific pituitary hormone, the condition is known as selective hypopituitarism. If there is decreased secretion of most or all pituitary hormones, the term panhypopituitarism is used.
Pituitary adenomas are tumors that occur in the pituitary gland. Most pituitary tumors are benign, approximately 35% are invasive and just 0.1% to 0.2% are carcinomas. Pituitary adenomas represent from 10% to 25% of all intracranial neoplasms and the estimated prevalence rate in the general population is approximately 17%.
Kallmann syndrome (KS) is a genetic disorder that prevents a person from starting or fully completing puberty. Kallmann syndrome is a form of a group of conditions termed hypogonadotropic hypogonadism. To distinguish it from other forms of hypogonadotropic hypogonadism, Kallmann syndrome has the additional symptom of a total lack of sense of smell (anosmia) or a reduced sense of smell. If left untreated, people will have poorly defined secondary sexual characteristics, show signs of hypogonadism, almost invariably are infertile and are at increased risk of developing osteoporosis. A range of other physical symptoms affecting the face, hands and skeletal system can also occur.
Adrenocorticotropic hormone deficiency is a rare disorder characterized by secondary adrenal insufficiency with minimal or no cortisol production and normal pituitary hormone secretion apart from ACTH. ACTH deficiency may be congenital or acquired, and its symptoms are clinically similar to those of glucocorticoid deficiency. Symptoms consist of weight loss, diminished appetite, muscle weakness, nausea, vomiting, and hypotension. Low blood sugar and hyponatremia are possible; however, blood potassium levels typically remain normal because affected patients are deficient in glucocorticoids rather than mineralocorticoids because of their intact renin-angiotensin-aldosterone system. ACTH may be undetectable in blood tests, and cortisol is abnormally low. Glucocorticoid replacement therapy is required. With the exception of stressful situations, some patients with mild or nearly asymptomatic disease may not require glucocorticoid replacement therapy. As of 2008 about two hundred cases have been described in the literature.
Laron syndrome (LS), also known as growth hormone insensitivity or growth hormone receptor deficiency (GHRD), is an autosomal recessive disorder characterized by a lack of insulin-like growth factor 1 production in response to growth hormone. It is usually caused by inherited growth hormone receptor (GHR) mutations.
Homeobox expressed in ES cells 1, also known as homeobox protein ANF, is a homeobox protein that in humans is encoded by the HESX1 gene.
The growth-hormone-releasing hormone receptor (GHRHR) is a G-protein-coupled receptor that binds growth hormone-releasing hormone. The GHRHR activates a Gs protein that causes a cascade of cAMP via adenylate cyclase. GHRHR is distinct from the growth hormone secretagogue receptor, where growth hormone releasing peptides act to release growth hormone.
CJC-1295, also known as DAC:GRF, is a synthetic analogue of growth hormone-releasing hormone (GHRH) and a growth hormone secretagogue (GHS) which was developed by ConjuChem Biotechnologies. It is a modified form of GHRH (1-29) with improved pharmacokinetics, especially in regard to half-life.
Autoimmune polyendocrine syndrome type 1 (APS-1), is a subtype of autoimmune polyendocrine syndrome. It causes the dysfunction of multiple endocrine glands due to autoimmunity. It is a genetic disorder, inherited in autosomal recessive fashion due to a defect in the AIRE gene , which is located on chromosome 21 and normally confers immune tolerance.
Isolated 17,20-lyase deficiency (ILD), also called isolated 17,20-desmolase deficiency, is a rare endocrine and autosomal recessive genetic disorder which is characterized by a complete or partial loss of 17,20-lyase activity and, in turn, impaired production of the androgen and estrogen sex steroids. The condition manifests itself as pseudohermaphroditism in males, in whom it is considered to be a form of intersex, and, in both sexes, as a reduced or absent puberty/lack of development of secondary sexual characteristics, resulting in a somewhat childlike appearance in adulthood.
Gonadotropin-releasing hormone (GnRH) insensitivity also known as Isolated gonadotropin-releasing hormone (GnRH)deficiency (IGD) is a rare autosomal recessive genetic and endocrine syndrome which is characterized by inactivating mutations of the gonadotropin-releasing hormone receptor (GnRHR) and thus an insensitivity of the receptor to gonadotropin-releasing hormone (GnRH), resulting in a partial or complete loss of the ability of the gonads to synthesize the sex hormones. The condition manifests itself as isolated hypogonadotropic hypogonadism (IHH), presenting with symptoms such as delayed, reduced, or absent puberty, low or complete lack of libido, and infertility, and is the predominant cause of IHH when it does not present alongside anosmia.
Hypogonadotropic hypogonadism (HH), is due to problems with either the hypothalamus or pituitary gland affecting the hypothalamic-pituitary-gonadal axis. Hypothalamic disorders result from a deficiency in the release of gonadotropic releasing hormone (GnRH), while pituitary gland disorders are due to a deficiency in the release of gonadotropins from the anterior pituitary. GnRH is the central regulator in reproductive function and sexual development via the HPG axis. GnRH is released by GnRH neurons, which are hypothalamic neuroendocrine cells, into the hypophyseal portal system acting on gonadotrophs in the anterior pituitary. The release of gonadotropins, LH and FSH, act on the gonads for the development and maintenance of proper adult reproductive physiology. LH acts on Leydig cells in the male testes and theca cells in the female. FSH acts on Sertoli cells in the male and follicular cells in the female. Combined this causes the secretion of gonadal sex steroids and the initiation of folliculogenesis and spermatogenesis. The production of sex steroids forms a negative feedback loop acting on both the anterior pituitary and hypothalamus causing a pulsatile secretion of GnRH. GnRH neurons lack sex steroid receptors and mediators such as kisspeptin stimulate GnRH neurons for pulsatile secretion of GnRH.
Kowarski syndrome describes cases of growth failure, despite the presence of normal or slightly high blood growth hormone by radioimmunoassay (RIA-GH) and low serum IGF1, and who exhibit a significant increase in growth rate following recombinant GH therapy.
The hypothalamic–pituitary–somatotropic axis, or hypothalamic–pituitary–somatic axis, also known as the hypothalamic–pituitary–growth axis, is a hypothalamic–pituitary axis which includes the secretion of growth hormone from the somatotropes of the pituitary gland into the circulation and the subsequent stimulation of insulin-like growth factor 1 production by GH in tissues such as, namely, the liver. Other hypothalamic–pituitary hormones such as growth hormone-releasing hormone, growth hormone-inhibiting hormone, and ghrelin (GHS) are involved in the control of GH secretion from the pituitary gland. The HPS axis is involved in postnatal human growth. Individuals with growth hormone deficiency or Laron syndrome show symptoms like short stature, dwarfism and obesity, but are also protected from some forms of cancer. Conversely, acromegaly and gigantism are conditions of GH and IGF-1 excess usually due to a pituitary tumor, and are characterized by overgrowth and tall stature.
