Growth hormone deficiency | |
---|---|
Other names | Pituitary dwarfism |
Growth hormone | |
Specialty | Endocrinology |
Symptoms | Short height [1] |
Complications | Low blood sugar, high cholesterol levels, poor bone density [1] [2] |
Types | Congenital, acquired [1] |
Causes | Not enough growth hormone [3] |
Risk factors | Genetics, trauma, infections, tumors, radiation therapy [2] |
Diagnostic method | Blood tests for growth hormone [2] |
Differential diagnosis | Small for gestational age, Turner syndrome, Noonan syndrome, Prader-Willi syndrome [2] |
Treatment | Growth hormone replacement [1] growth hormone injections |
Frequency | Unclear [2] |
Growth hormone deficiency (GHD), or human growth hormone deficiency, is a medical condition resulting from not enough growth hormone (GH). [3] Generally the most noticeable symptom is that an individual attains a short height. [1] Newborns may also present low blood sugar or a small penis size. [2] In adults there may be decreased muscle mass, high cholesterol levels, or poor bone density. [1]
GHD can be present at birth or develop later in life. [1] Causes may include genetics, trauma, infections, tumors, or radiation therapy. [2] Genes that may be involved include GH1 , GHRHR , or BTK . [3] In a third of cases no cause is apparent. [2] The underlying mechanism generally involves problems with the pituitary gland. [2] Some cases are associated with a lack of other pituitary hormones, in which case it is known as combined pituitary hormone deficiency. [4] Diagnosis involves blood tests to measure growth hormone levels. [2]
Treatment is by growth hormone replacement using synthetic human growth hormone. [1] The frequency of the condition is unclear. [2] Most cases are initially noticed in children. [1] The genetic forms of this disease are estimated to affect about 1 in 7,000 people. [3] Most types occur equally in males and females though males are more often diagnosed. [2]
Severe prenatal deficiency of GH, as occurs in congenital hypopituitarism, has little effect on fetal growth. However, prenatal and congenital deficiency can reduce the size of a male's penis, especially when gonadotropins are also deficient. Besides micropenis in males, additional consequences of severe deficiency in the first days of life can include hypoglycemia and exaggerated jaundice (both direct and indirect hyperbilirubinemia).[ citation needed ]
Even congenital GH deficiency does not usually impair length growth until after the first few months of life. From late in the first year until mid-teens, poor growth and/or shortness is the hallmark of childhood GH deficiency. Growth is not as severely affected in GH deficiency as in untreated hypothyroidism, but growth at about half the usual velocity for age is typical. It tends to be accompanied by delayed physical maturation so that bone maturation and puberty may be several years delayed. When severe GH deficiency is present from birth and never treated, adult heights can be as short as 48–65 inches (120–170 cm).[ citation needed ]
Severe GH deficiency in early childhood also results in slower muscular development, so that gross motor milestones such as standing, walking, and jumping may be delayed. Body composition (i.e., the relative amounts of bone, muscle, and fat) is affected in many children with severe deficiency, so that mild to moderate chubbiness is common (though GH deficiency alone rarely causes severe obesity). Some severely GH-deficient children have recognizable, cherubic facial features characterized by maxillary hypoplasia and forehead prominence. [5]
Other side effects in children include sparse hair growth and frontal recession, and pili torti and trichorrhexis nodosa are also sometimes present. [6] : 501
Recognised effects include: [7] [8]
Growth hormone deficiency in childhood commonly has no identifiable cause (idiopathic), and adult-onset GHD is commonly due to pituitary tumours and their treatment or to cranial irradiation. [9] A more complete list of causes includes:
There are a variety of rare diseases that resemble GH deficiency, including the childhood growth failure, facial appearance, delayed bone age, and low insulin-like growth factor-1 (IGF-1) levels. However, GH testing elicits normal or high levels of GH in the blood, demonstrating that the problem is not due to a deficiency of GH but rather to a reduced sensitivity to its action. Insensitivity to GH is traditionally termed Laron dwarfism, but over the last 15 years many different types of GH resistance have been identified, primarily involving mutations of the GH binding protein or receptors. [13]
Familial isolated growth hormone deficiency (IGHD) can be inherited as an autosomal recessive (type I), autosomal dominant (type II), or X-linked (type III) characteristic. [14]
As an adult ages, it is normal for the pituitary to produce diminishing amounts of GH and many other hormones, particularly the sex steroids. Physicians, therefore, distinguish between the natural reduction in GH levels which comes with age, and the much lower levels of "true" deficiency. Such deficiency almost always has an identifiable cause, with adult-onset GHD without a definable cause ("idiopathic GH deficiency") extremely rare. [15] GH does function in adulthood to maintain muscle and bone mass and strength, and has poorly understood effects on cognition and mood. [16]
Although GH can be readily measured in a blood sample, testing for GH deficiency is constrained by the fact that levels are nearly undetectable for most of the day. This makes simple measurement of GH in a single blood sample useless for detecting deficiency. Physicians, therefore use a combination of indirect and direct criteria in assessing GHD, including: [17]
"Provocative tests" involve giving a dose of an agent that will normally provoke a pituitary to release a burst of growth hormone. An intravenous line is established, the agent is given, and small amounts of blood are drawn at 15-minute intervals over the next hour to determine if a rise of GH was provoked. Agents which have been used clinically to stimulate and assess GH secretion are arginine, [18] levodopa, clonidine, epinephrine and propranolol, glucagon, and insulin. An insulin tolerance test has been shown to be reproducible, age-independent, and able to distinguish between GHD and normal adults, [18] and so is the test of choice.
Severe GH deficiency in childhood additionally has the following measurable characteristics: [19]
In childhood and adulthood, the diagnosing doctor will look for these features accompanied by corroboratory evidence of hypopituitarism such as deficiency of other pituitary hormones, a structurally abnormal pituitary, or a history of damage to the pituitary. This would confirm the diagnosis; in the absence of pituitary pathology, further testing would be required.[ citation needed ]
Growth hormone deficiency can be congenital or acquired in childhood or adult life. It can be partial or complete. It is usually permanent, but sometimes transient. It may be an isolated deficiency or occur in association with deficiencies of other pituitary hormones. [20]
The term hypopituitarism is often used interchangeably with GH deficiency but more often denotes GH deficiency plus deficiency of at least one other anterior pituitary hormone. When GH deficiency (usually with other anterior pituitary deficiencies) is associated with posterior pituitary hormone deficiency (usually diabetes insipidus), the condition is termed panhypopituitarism. [21]
GH deficiency is treated by replacing GH with daily injections under the skin or into muscle. Until 1985, growth hormone for treatment was obtained by extraction from human pituitary glands collected at autopsy. Since 1985, recombinant human growth hormone (rHGH) is a recombinant form of human GH produced by genetically engineered bacteria, manufactured by recombinant DNA technology. In both children and adults, costs of treatment in terms of money, effort, and the impact on day-to-day life, are substantial. [22]
GH treatment is not recommended for children who are not growing despite having normal levels of growth hormone, and in the UK it is not licensed for this use. [23] Children requiring treatment usually receive daily injections of growth hormone. Most pediatric endocrinologists monitor growth and adjust dose every 3–6 months and many of these visits involve blood tests and x-rays. Treatment is usually extended as long as the child is growing, and lifelong continuation may be recommended for those most severely deficient. Nearly painless insulin syringes, pen injectors, or a needle-free delivery system reduce the discomfort. Injection sites include the biceps, thigh, buttocks, and stomach. Injection sites should be rotated daily to avoid lipoatrophy. Treatment is expensive, costing as much as US$10,000 to $40,000 a year in the US.[ citation needed ]
GH supplementation is not recommended medically for the physiologic age-related decline in GH/IGF secretion. [9] [15] It may be appropriate in diagnosed adult-onset deficiency, where a weekly dose of approximately 25% of that given to children is given. Lower doses again are called for in the elderly to reduce the incidence of side effects and maintain age-dependent normal levels of IGF-1. [24]
In many countries, including the UK, the majority view among endocrinologists is that the failure of treatment to provide any demonstrable, measurable benefits in terms of outcomes means treatment is not recommended for all adults with severe GHD, [25] and national guidelines in the UK as set out by NICE suggest three criteria which all need to be met for treatment to be indicated:
Where treatment is indicated, duration is dependent upon indication.
Cost of adult treatment in the UK is 3000-4000 GBP annually. [25]
When treated with GH, a severely deficient child will begin to grow faster within months. In the first year of treatment, the rate of growth may increase from half as fast as other children are growing to twice as fast (e.g., from 1 inch a year to 4 inches, or 2.5 cm to 10). Growth typically slows in subsequent years, but usually remains above normal so that over several years a child who had fallen far behind in their height may grow into the normal height range. Excess adipose tissue may be reduced. [26]
GH treatment can confer a number of measurable benefits to severely GH-deficient adults, such as enhanced energy and strength, and improved bone density. Muscle mass may increase at the expense of adipose tissue. Although adults with hypopituitarism have been shown to have a reduced life expectancy, and a cardiovascular mortality rate of more than double controls, [25] treatment has not been shown to improve mortality, although blood lipid levels do improve. Similarly, although measurements of bone density improve with treatment, rates of fractures have not been shown to improve. [25]
Effects on quality of life are unproven, with a number of studies finding that adults with GHD had near-normal indicators of QoL at baseline (giving little scope for improvement), and many using outdated dosing strategies. However, it may be that those adults with poor QoL at the start of treatment do benefit. [9]
The incidence of idiopathic GHD in infants is about 1 in every 3800 live births, [27] and rates in older children are rising as more children survive childhood cancers which are treated with radiotherapy, although exact rates are hard to obtain. [10] The incidence of genuine adult-onset GHD, normally due to pituitary tumours, is estimated at 10 per million. [25]
Like many other 19th century medical terms which lost precise meaning as they gained wider currency, "midget" as a term for someone with severe proportional shortness acquired pejorative connotations and is no longer used in a medical context. [28]
Notable modern pop cultural figures with growth hormone deficiency include actor and comedian Andy Milonakis, who has the appearance and voice of an adolescent boy despite being in his 40s. [29] [30] Argentine footballer Lionel Messi was diagnosed at age 10 with growth hormone deficiency and was subsequently treated. [31] TLC reality star Shauna Rae was affected by a medically-caused growth hormone deficiency resulting from childhood glioblastoma cancer treatment. [32] Oscar winning actress Linda Hunt was diagnosed as having this condition when a teenager.
Congenital iodine deficiency syndrome (CIDS), also called cretinism, is a medical condition present at birth marked by impaired physical and mental development, due to insufficient thyroid hormone production (hypothyroidism) often caused by insufficient dietary iodine during pregnancy. It is one cause of underactive thyroid function at birth, called congenital hypothyroidism. If untreated, it results in impairment of both physical and mental development. Symptoms may include: goiter, poor length growth in infants, reduced adult stature, thickened skin, hair loss, enlarged tongue, a protruding abdomen, delayed bone maturation and puberty in children, mental deterioration, neurological impairment, impeded ovulation, and infertility in adults.
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.
Adrenal insufficiency is a condition in which the adrenal glands do not produce adequate amounts of steroid hormones. The adrenal glands—also referred to as the adrenal cortex—normally secrete glucocorticoids, mineralocorticoids, and androgens. These hormones are important in regulating blood pressure, electrolytes, and metabolism as a whole. Deficiency of these hormones leads to symptoms ranging from abdominal pain, vomiting, muscle weakness and fatigue, low blood pressure, depression, mood and personality changes to organ failure and shock. Adrenal crisis may occur if a person having adrenal insufficiency experiences stresses, such as an accident, injury, surgery, or severe infection; this is a life-threatening medical condition resulting from severe deficiency of cortisol in the body. Death may quickly follow.
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. In the 1950s IGF-1 was called "sulfation factor" because it stimulated sulfation of cartilage in vitro, and in the 1970s due to its effects it was termed "nonsuppressible insulin-like activity" (NSILA).
Delayed puberty is when a person lacks or has incomplete development of specific sexual characteristics past the usual age of onset of puberty. The person may have no physical or hormonal signs that puberty has begun. In the United States, girls are considered to have delayed puberty if they lack breast development by age 13 or have not started menstruating by age 15. Boys are considered to have delayed puberty if they lack enlargement of the testicles by age 14. Delayed puberty affects about 2% of adolescents.
Hypogonadism means diminished functional activity of the gonads—the testicles or the ovaries—that may result in diminished production of sex hormones. Low androgen levels are referred to as hypoandrogenism and low estrogen as hypoestrogenism. These are responsible for the observed signs and symptoms in both males and females.
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.
Sheehan's syndrome, also known as postpartum pituitary gland necrosis, occurs when the pituitary gland is damaged due to significant blood loss and hypovolemic shock or stroke, originally described during or after childbirth leading to decreased functioning of the pituitary gland (hypopituitarism). Classically, in the milder partial form, the mother is unable to breastfeed her baby, due to failure of the pituitary to secrete the hormone prolactin, and also has no more periods, because FSH and LH are not secreted. Although postmenopausal, the mother with this milder form of Sheehan's syndrome does not experience hot flushes, because the pituitary fails to secrete FSH. The failure to breastfeed and amenorrhea no more periods, were seen as the syndrome, but we now view Sheehan's as the pituitary failing to secrete 1-5 of the 9 hormones that it normally produces (the anterior lobe of the pituitary produces FSH, LH, prolactin, ACTH ,TSH and GH ; the posterior pituitary produces ADH and Oxytocin, i.e. the pituitary is involved in the regulation of many hormones. It is very important to recognise Sheehan' stroke as, the ACTH deficiency Sheehan's in the presence of the stress of a bacterial infection, such as a urine infection, will result in death of the mother from Addisonian crisis. This gland is located on the under-surface of the brain, the shape of a cherry and the size of a chickpea and sits in a pit or depression of the sphenoid bone known as the sella turcica. The pituitary gland works in conjunction with the hypothalamus, and other endocrine organs to modulate numerous bodily functions including growth, metabolism, menstruation, lactation, and even the "fight-or-flight" response. These endocrine organs,, release hormones in very specific pathways, known as hormonal axes. For example, the release of a hormone in the hypothalamus will target the pituitary to trigger the release thyroid stimulating hormone, and the pituitary's released hormone will target the next organ in the pathway i.e. the thyroid to release thyroxin. Hence, damage to the pituitary gland can have downstream effects on any of the aforementioned bodily functions.
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, with an estimated prevalence rate in the general population of approximately 17%.
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.
A micropenis or microphallus is an unusually small penis. A common criterion is a dorsal penile length of at least 2.5 standard deviations smaller than the mean human penis size for age. A micropenis is stretched penile length equal to or less than 1.9 cm in term infants, and 9.3 cm in adults. The condition is usually recognized shortly after birth. The term is most often used medically when the rest of the penis, scrotum, and perineum are without ambiguity, such as hypospadias. Traditionally, a microphallus describes a micropenis with hypospadias. Micropenis incidence is about 1.5 in 10,000 male newborns in North America.
Ibutamoren is a potent, long-acting, orally-active, selective, and non-peptide agonist of the ghrelin receptor and a growth hormone secretagogue, mimicking the growth hormone (GH)-stimulating action of the endogenous hormone ghrelin. It has been shown to increase the secretion of several hormones including GH and insulin-like growth factor 1 (IGF-1) and produces sustained increases in the plasma levels of these hormones while also raising cortisol levels.
Acromegaly is a disorder that results in excess growth of certain parts of the human body. It is caused by excess growth hormone (GH) after the growth plates have closed. The initial symptom is typically enlargement of the hands and feet. There may also be an enlargement of the forehead, jaw, and nose. Other symptoms may include joint pain, thicker skin, deepening of the voice, headaches, and problems with vision. Complications of the disease may include type 2 diabetes, sleep apnea, and high blood pressure.
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.
Hormonal breast enhancement or augmentation is a highly experimental potential medical treatment for the breasts in which hormones or hormonal agents such as estrogen, progesterone, growth hormone (GH), and insulin-like growth factor 1 (IGF-1) are utilized or manipulated to produce breast enlargement in women. It is a possible alternative or supplement to surgical breast augmentation with breast implants or fat transfer and other means of medical breast enlargement.
Isolated growth hormone deficiency (IGHD) is a rare congenital disorder characterized by growth hormone deficiency and postnatal growth failure. It is divided into four subtypes that vary in terms of cause and clinical presentation. They include IGHD IA, IGHD IB, IGHD II, and IGHD III.