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Addison's Disease Information
Addison's disease
is an endocrine or hormonal disorder that occurs
in all age groups and afflicts men and women equally.
The disease is characterized by weight loss, muscle
weakness, fatigue, low blood pressure, and sometimes
darkening of the skin in both exposed and non
exposed parts of the body.
Addison's disease
occurs when the adrenal glands do not produce
enough of the hormone cortisol and, in some cases,
the hormone aldosterone. The disease is also called
adrenal insufficiency, or hypocortisolism.
Cortisol
Cortisol is
normally produced by the adrenal glands, located
just above the kidneys. It belongs to a class
of hormones called glucocorticoids, which affect
almost every organ and tissue in the body. Scientists
think that cortisol has possibly hundreds of effects
in the body. Cortisol's most important job is
to help the body respond to stress. Among its
other vital tasks, cortisol
- Helps maintain blood pressure
and cardiovascular functions
- Helps slow the immune system's
inflammatory response
- Helps balance the effects
of insulin in breaking down sugar for energy
- Helps regulate the metabolism
of proteins, carbohydrates, and fats
- Helps maintain proper arousal
and sense of well-being
Because cortisol
is so vital to health, the amount of cortisol
produced by the adrenals is precisely balanced.
Like many other hormones, cortisol is regulated
by the brain's hypothalamus and the pituitary
gland, a bean-sized organ at the base of the brain.
First, the hypothalamus sends "releasing
hormones" to the pituitary gland. The pituitary
responds by secreting hormones that regulate growth
and thyroid and adrenal function. One of the pituitary's
main functions is to secrete ACTH (Adrenocorticotropin),
a hormone that stimulates the adrenal glands.
When the adrenals receive the pituitary's signal
in the form of ACTH, they respond by producing
cortisol. Completing the cycle, cortisol then
signals the pituitary to lower secretion of ACTH.
The test for
diagnosing addison's disease is an ACTH test.
In this test, blood cortisol, urine cortisol,
or both are measured before and after a synthetic
form of ACTH is given by injection. In the so-called
short, or rapid, ACTH test, measurement of cortisol
in blood is repeated 30 to 60 minutes after and
intravenous ACTH injection. The normal response
after an injection of ACTH is a rise in blood
and urine cortisol levels. Patients with either
form of adrenal insufficiency respond poorly or
do not respond at all. |
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