Endocrinology

  • About Endocrinology
    About Endocrinology

    Endocrinology
  • About Endocrinology

    The endocrine system helps to maintain stable and relatively constant internal conditions in the body. It regulates many chemical reactions necessary for us to grow, mature, reproduce, metabolise and behave normally.

     The major components of the endocrine system are glands and hormones.

     Endocrine glands release their hormones directly into the blood stream. Blood carries the hormones to the target sites. These are specific cells or organs, often some distance from the endocrine gland itself, where each hormone triggers a certain response.

     The major endocrine glands are:

    The brain – particularly the hypothalamus, the pituitary gland, thyroid gland, parathyroid glands, adrenal glands, ovaries (females only) and testes (male only).

     

    The hypothalamus and the pituitary gland

     Although the brain is the controller of the central nervous system , it also has a crucial endocrine function.

     The hypothalamus is an area of the brain that sits just above the pituitary gland. The hypothalamus secretes regulating hormones, which leads to the release or inhibition of pituitary hormones depending on the needs of the body.

     The pituitary gland is often referred to as the master controller of the endocrine system. It produces the following hormones: growth hormone, adrenocorticotrophic hormone, thyroid-stimulating hormone, folicle-stimulating hormone, lutenising hormone, prolactin, vasopressin, oxytocin and melanocyte-stimulating hormone. The two sections of the pituitary are known as the anterior and posterior lobes.

     The pituitary gland stimulates other endocrine glands and other target sites within the body. Together with the hypothalamus, the pituitary orchestrates the vast range of the body’s hormonal interactions.

     The pituitary gland has very wide-ranging connections. This means that a disorder of the pituitary gland can produce a wide range of signs and symptoms.

     

     

    Growth hormone

     Growth hormone (GH) is one of the main hormones produced by the pituitary gland, and is a crucial factor in promoting normal growth and development in the body. Its action determines how the body is built, how it functions, and in particular the way bones develop.

     Growth hormone is released in a cycle of short bursts throughout the day, roughly once every four hours, though about 70 per cent of the total growth hormone is secreted during the early hours of sleep, particularly during dreaming.

     Once sufficient growth hormone has been released, the increased concentration in the blood feeds back to the hypothalamus and a second hormone, called somatostatin (also known as GH-inhibiting factor), is released telling the pituitary gland to stop secreting growth hormone for the moment.

     

    Role of growth hormone in growth

     During childhood and puberty, growth hormone secretion is at its highest, causing bone cells to multiply by acting on 'growth plates' at the end of each tubular bone. It is the increase in the length of the long bones in the body that causes the body to grow taller and overall growth causes the skeleton to take on an adult shape.

     After growth is complete, the growth plates of the long bones fuse together and close; preventing further lengthening, and the secretion of growth hormone gradually falls to the much lower levels, typical of adulthood.

     

    Disorders of the endocrine system

     The feedback mechanism of the endocrine system is designed to prevent overproduction (hypersecretion) or underproduction (hyposecretion) of any given hormone. However in some disease conditions there is an imbalance in the regulation.

     The under- or overproduction of hormones from the pituitary gland cause several problems. Imbalance in the production of growth hormone affects the natural growth of children. Any shortfall in the production of growth hormone during childhood and puberty will affect the height and development of a child, and once the growth plates of the long bones have closed, growth hormone is unable to have any further effect on the height of an individual.

    All information on this site is intended for UK audiences only.

  • Growth disorders
    Growth disorders

    Endocrinology
  • Growth disorders

    Growth is one of the complex and amazing facts of life that most people take for granted but it can be a cause for concern for parents if they have a child who is shorter than others of the same age and does not appear to be growing any taller.

     Causes of delayed growth

     There are a large number of medical, genetic and external factors that can delay or inhibit normal growth. These include conditions such as Growth Hormone Deficiency (GHD) in children, Turner's syndrome in girls, Down's syndrome, achondroplasia (defective growth of cartilage cells in the bones of the limbs) and various malfunctions of the endocrine system.

     Chronic diseases and illnesses can also have a detrimental effect on growth including Inflammatory Bowel Disease, chronic renal insufficiency, heart disease, factors such as malnutrition, drug and alcohol abuse, neglect, chronic stress and lack of exercise.

     

    However, in many cases the cause of delayed or restricted growth is not known.

     Many children are smaller than average during childhood yet end up reaching a normal adult height. But for some, a more normal adult height will not be achieved without treatment with supplemental human growth hormone (hGH). These include children with GHD and Turner's syndrome.

     One out of 2,500 to 5,000 children is born with a deficient growth hormone production resulting in impaired physical development, and another one in 2,000 to 2,500 girls are born with the genetic defect Turner's syndrome. Both disorders may result in decreased final height, which may be improved by supplemental somatropin.

    All information on this site is intended for UK audiences only.

  • Growth disorders – Growth Hormone Deficiency (GHD)
    Growth disorders – Growth Hormone Deficiency (GHD)

    Endocrinology
  • Growth Hormone Deficiency (GHD)

    In children

    A child with an inadequate production of growth hormone (reduced or non-existent) may have a normal height and weight at birth, but the child's physical development following birth is severely impaired.

     The under-secretion of human growth hormone during childhood and puberty slows bone growth and teeth development. It also causes the growing plates of the long bones to close before normal height is reached.

                     

     

    In addition, other organs of the body fail to grow and the body proportions remain childlike.

     Without treatment, the child with GHD risks the development of a range of complications, as well as having a short stature.

    All information on this site is intended for UK audiences only.

  • Growth disorders – Turner's syndrome
    Growth disorders – Turner's syndrome

    Endocrinology
  • Turner's syndrome

    Turner's syndrome is a common genetic defect that affects girls and women and occurs in about one out of every 2,000 to 2,500 female births.

     In Turner's syndrome all or part of one of the two X-chromosomes is missing but the reason why this happens is not known. This defect can cause a number of physical and medical problems and in some cases these create educational and behavioural concerns.

     The extent of the defect to the X chromosome varies, thus every case of Turner's syndrome is individual and each affected girl may show  only a few of the possible characteristics that can be associated with the syndrome.

    Short stature is a common characteristic of Turner's syndrome resulting in a decreased final adult height and is generally accompanied by a failure of the ovaries and infertility.

    Growth failure in Turner's syndrome

     The reasons for the growth retardation in Turner's syndrome are not entirely understood, but patients are generally not deficient in growth hormone. The pituitary gland produces adequate amounts but the long bones do not respond.

     The growth plates appear to be resistant to the action of their body's growth hormone, yet the growth hormone functions normally in controlling metabolism and organ development. By treating with supplemental hGH the resistance can be overcome, creating growth in the long bones. Female supplemental hormones may need to be given as well.

     As it is a genetic problem, the affected individual will be faced with the consequences of the syndrome all her life but nevertheless can expect to lead a healthy life with appropriate care and treatment.

    All information on this site is intended for UK audiences only.

  • Growth disorders – Growth Hormone Therapy
    Growth disorders – Growth Hormone Therapy

    Endocrinology
  • Growth Hormone Therapy

    Synthetic human growth hormone (hGH) is used to replace the growth hormone short-fall in people who do not produce enough of their own, or have an inadequate response to that which is produced.

     In all cases supplemental growth hormone has to be given on a daily basis, usually as a nightly injection at bedtime. The dose is calculated and adjusted for each individual case.

     Use in children

     Deficient children require hGH supplements throughout childhood. It is important that hGH given to stimulate growth is be administered before the growth plates of the long bones close, prompt treatment can result in children gaining of several extra centimetres of height.

     Use in Turner's syndrome

     In Turner's syndrome large doses of growth hormone often have to be given and this approach has been found to be effective in increasing final height especially in combination with appropriate very-low-dose oestrogen replacement.

    All information on this site is intended for UK audiences only.

     

     

    Synthetic growth hormone

     All replacement hGH is produced using recombinant DNA technology. This synthetic hGH is identical to the body’s own growth hormone, it is a protein or peptide chain containing 191 amino acids.

     Supplemental hGH cannot be taken orally, as being a protein it will be broken down and digested. It therefore has to be injected, but regular injections can be very off-putting, particularly for a child.

     The mode of administration can have a strong bearing on the acceptability of treatment and hence ultimate compliance and treatment success. Improvements to injection devices are constantly being developed to make the process easier and more comfortable for patients.

  • Growth disorders – Links
    Growth disorders – Links

    Endocrinology
  • Links

    For more information we recommend you to visit the following websites.

     www.netdoctor.co.uk/diseases/facts/lackofgrowthhormones.htm (last accessed 20.07.15)

     www.netdoctor.co.uk/diseases/facts/growthabnormalities.htm (last accessed 20.07.15)

     

     

    www.emedicine.com/med/topic930.htm (last accessed 20.07.15)

     

     Please note that Ferring cannot accept liability for the content on the above sites, since they are not managed or controlled by Ferring.

    All information on this site is intended for UK audiences only.

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