›› Human Growth Hormone
Human growth hormone
is a protein that acts as a chemical messenger and it is responsible
for a variety of vital functions in humans. Most vertebrates
have a form of growth hormone, often abbreviated as GH, while the human
version is often abbreviated as hGH for human growth hormone.
Human growth hormone is also known as somatotropin.
Somatotropin is produced by the ‘somatotrope’ cells
of the anterior pituitary gland, and its secretion into the blood is
controlled by chemical signals from the nearby hypothalamus
gland. Both the pituitary and hypothalamus glands are located
in the middle of the brain. Human growth hormone is quite
large compared to most hormones, consisting of 191 amino acids.
Somatotropin plays a crucial role in stimulating cell growth and
reproduction, and is at its peak levels in humans at adolescence, when
much of a person’s growth is occurring. Human
growth hormone continues to play an important role throughout adult
life, however. It is released in small amounts during sleep,
and helps to control cellular repair, metabolism, muscle growth and the
maintenance of normal brain function. It also helps to boost
the immune system.
Human growth hormone is a very powerful protein, too much or too little
of it can lead to a number of serious conditions. A tumor in
the pituitary gland can result in too much hGH, which can eventually
lead to the condition known as
‘acromegaly’. Acromegaly involves
thickening digits, impinged nerves, blurred vision, and sometimes a
form of diabetes. If the tumor is removed, the effects of
acromegaly can normally be reversible, however if the tumor occurred
during childhood an abnormal amount of permanent growth may
happen. This is sometimes referred to as
‘gigantism’.
Too little hGH can be caused by a number of different
factors. A genetic mutation in the gene coding for the
hormone, a problem with the chemical signal that controls hGH release
or any kind of structural malfunctions in the pituitary or hypothalamus
glands can cause a lack of the hormone. If the hormone is
deficient in childhood, a lack of overall growth will result, leading
to a condition sometimes referred to as
‘dwarfism’. If the deficiency begins
during adulthood the symptoms often include fatigue, loss of muscle
mass, and heart disease.
A synthetic form of the hormone is available today as a treatment for
conditions resulting in a lack of the natural version.
Treatment with human growth hormone is also sometimes used for AIDS
patients to help them maintain weight in later stages of the disease,
in the treatment of fibromyalgia, ulcerative colitis, Crohn’s
disease. A few somewhat controversial uses of the hormone
include helping bodybuilders gain muscle, obese people lose weight, and
elderly people reverse some of the effects of their age.
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