What you need to know about Human Growth Hormone
Human growth hormone is a peptide hormone that regulates growth and cell reproduction in animals and humans.
The pituitary gland naturally produces growth hormone, which acts as a messenger to help the body grow.
Growth hormone tells the liver to produce another hormone, called insulin-like growth factor, that travels to muscles, organs, and bones and tells them to grow.
Scientists first isolated HGH in 1956. Three years later, NHS doctors began to use it in the treatment of children suffering from stunted growth.
Increased height during childhood is the most widely known effect of GH. Height appears to be stimulated by at least two mechanisms:
HGH is synthesized and secreted from the anterior pituitary gland in a pulsatile manner throughout the day; surges of secretion occur at 3- to 5-hour intervals.
The largest and most predictable of these GH peaks occurs about an hour after onset of sleep.
Nearly fifty percent of HGH secretion occurs during the third and fourth NREM sleep stages.
A number of factors are known to affect HGH secretion and in brief, these include ;
~ Body fat
~ Other hormones
More on those factors >>>
Young adolescents secrete H.G.H at the rate of about 700 μg/day, while healthy adults secrete H.G.H at the rate of about 400 μg/day.
It is made throughout a person’s lifetime but is more plentiful during youth.
A relatively recent discovery is the existence of growth hormone deficiency in adults (GHDA), which has shed further light on the function of this busy little hormone.
People with GHDA have a relatively low muscle mass and high body fat, creating a tendency to obesity, an increased risk of heart disease and a greatly reduced exercise capacity.
Treatment of this condition usually requires regular injections of growth hormone.
In addition to increasing height in children and adolescents, HGH are known to make you feel younger thus your body must produce H. G. H or it would not be able to function.
What happens if too much Growth hormones is released?
In adults, excessive growth hormone for a long period of time produces a condition known as acromegaly in which patients have swelling of the hands and feet and altered facial features. These patients also have organ enlargement and serious functional disorders such as high blood pressure, diabetes and heart disease.
What causes acromegaly?
Acromegaly is usually caused by a tumor of the cells which make growth hormone in the pituitary gland.
An increase in growth hormone before children reach their final height can lead to excessive growth of long bones, resulting in the child being abnormally tall. This is commonly known as gingatism
What are the signs and symptoms of acromegaly?
People with acromegaly may suffer with headaches, aches and pains in their bones and joints and increased sweating.
People who have not seen them for some time may be aware of a change in their appearance and this can often be seen when looking at photographs over a number of years.
Changes in the appearance of the face include enlargement of the nose, prominent jaw and forehead (with an increase in skin creases), a big tongue and spaces appearing between the teeth.
People with acromegaly tend to snore loudly in bed at night and can suffer with morning headaches and sleepiness during the day. This is called obstructive sleep apnoea.
Occasionally the benign pituitary tumour can press on the nerves to the eyes leading to a loss of vision. Usually the vision in the middle remains clear, but the outer vision can be blurred or not there at all.
People with acromegaly can also suffer from high blood pressure, diabetes and arthritis. The high blood pressure and diabetes tend to improve when acromegaly is treated.
What is gigantism?
Gigantism is an endocrine disorder resulting from long-term secretion of too much growth hormone which accelerates the growth of muscle, bones and connective tissue in childhood or adolescence before the end of puberty.
The consequence is an accelerated growth rate and increased height as well as a number of additional soft tissue changes. When left untreated or uncontrolled, some individuals suffering from gigantism have grown in excess of 8 feet (2.43m) tall.
The most famous example is that of Robert Wadlow, the tallest person in history at 8ft 11 in tall (2.71m).
Gigantism is very similar to acromegaly. Acromegaly is also caused by excess growth hormone secretion but during adulthood rather than childhood. This means that height is normal as the growth plates have fused before the excess growth hormone secretion occurs.
What causes gigantism?
Gigantism is almost always caused by a non-cancerous tumor and in the case of gigantism, causes secretion of too much growth hormone.
Pituitary tumours can be small in size or large .
However, in gigantism they are frequently large and invade nearby brain tissue. The size of the adenoma directly affects the signs and symptoms experienced by the individual .
What are the signs and symptoms of gigantism?
The signs and symptoms of gigantism are the accelerated growth leading to above-normal expected height for a child of their age.
The effects of the growth hormone on bone, ligaments and soft tissue swelling can lead to coarse facial features, excessively large hands and feet with thick fingers and toes, prominent foreheads and jaws.
Larger tumours can damage the function of the normal pituitary gland causing failure of secretion of other hormones .
Larger tumors may also cause headaches, visual field disturbances and nausea as a result of the tumour pressing on the brain and nerves to the eyes.
In some cases, puberty may be delayed if pressure from the tumor on the pituitary gland results in failure of sex hormone secretion and thus allows further growth of the skeleton.
How common is gigantism?
Gigantism is an extremely rare condition which most endocrinologists may come across only a couple of times in their whole careers. Only approximately six new cases occur each year in the United Kingdom.
Is gigantism inherited?
Gigantism is generally not inherited. There are, however, a number of rare endocrine conditions associated with gigantism such as McCune Albright syndrome and multiple endocrine neoplasia type 1.
A genetic mutation in the menin gene can be identified in affected families who have multiple endocrine neoplasia type 1. Gigantism seen in these conditions is still rare.
Recently, a new possible cause of pituitary tumours in families has been suggested, particularly tumours secreting growth hormone .
These often occur at a relatively young age and are thought to be caused by a genetic mutation.
Other roles played by this tiny hormone include;
1. Helps to increase protein manufacture.
2. Plays a role in the upkeep and proper performance of pancreatic islets
3. Reduces absorption of glucose by the liver.
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