Addison's disease (chronic adrenal insufficiency) is a rare
and progressive disorder that affects between one and six in
every 100,000 people. It affects people of both sexes and
The human body has two adrenal glands, one
on top of each kidney. These glands form part of the
endocrine system, which works with the nervous system and
the immune system to help the body cope with different
events and stresses. Addison's disease is caused by the
inability of the adrenal glands to make sufficient amounts
of regulating hormones.
Adrenaline is the best known
of the hormones that are secreted by the adrenal glands in
the adrenal medulla (the central part of the gland). The
adrenal cortex (the outer part) also produces important
hormones, the corticosteroids. They include cortisol,
aldosterone and supplementary sex hormones.
person with Addison's disease, only the adrenal cortex is
affected. The person cannot produce enough glucocorticoid or
cortisol and, occasionally, also fails to produce sufficient
mineralocorticoid. Levels of aldosterone are nearly always
low in people with Addison’s disease.
Causes of Addison's disease
Most cases of Addison's
disease are caused by an autoimmune response that attacks and
damages the adrenal glands over time. Other causes include:
Surgical removal of particular tumours in
the adrenal or pituitary glands or the hypothalamus.
of Addison's disease
The symptoms of Addison's disease can
include any or all of the following:
Loss of appetite and
Nausea, vomiting or diarrhoea
Chronic, worsening fatigue
Low blood pressure
Hypoglycaemia, or low blood sugar
levels (especially in children)
Increased pigmentation of the
skin, particularly around scars and bony areas
no menstrual periods in women
Mood swings, mental confusion
or loss of consciousness.
These symptoms can develop quickly
(especially in children and teenagers), or progress slowly for
20 years or more. Many symptoms can mimic other diseases, so
diagnosis can be delayed.
The hormone cortisol
Cortisol is produced by the outer layer of the adrenal gland,
called the adrenal cortex. The quantities of cortisol released
by the adrenal glands are closely monitored by the master gland
of the endocrine system, the pituitary, which is located in the
The workings of the pituitary are governed by
another brain structure, the hypothalamus. When cortisol levels
are too low, the pituitary secretes the stimulating hormone
adrenocorticotropin (ACTH). On the other hand, high levels of
cortisol cause the pituitary gland to decrease ACTH secretion,
which slows cortisol production.
Cortisol plays many
vital roles and is essential to many body functions because it:
Works with adrenaline to help the body manage physical and
Converts protein into glucose to boost
flagging blood sugar levels
Works in tandem with the hormone
insulin to maintain constant blood sugar levels
Helps the body maintain a constant blood
Helps the workings of the immune system.
Aldosterone is a mineralocorticoid, also
produced by the adrenal cortex. The amount of aldosterone in the
body is monitored by the kidneys, which secrete hormones to
increase or decrease aldosterone production. Aldosterone
regulates electrolytes (such as sodium and potassium) in the
blood. This helps to maintain blood pressure and heart function.
If too much sodium is excreted by the kidneys, a considerable
amount of body fluid is also lost. This reduces blood volume and
drops blood pressure. Too much or too little potassium can
affect the way the heart functions.
Addison's disease can occur gradually, and is
defined when approximately 90 per cent of the adrenal gland(s)
is damaged. This is known as primary adrenal insufficiency.
Around seven out of 10 cases of Addison's disease are caused by
an autoimmune response, where the body's own immune cells attack
and destroy the adrenal glands. In some cases, other glands of
the endocrine system are affected by an autoimmune response, in
a condition called polyendocrine deficiency syndrome.