Addison’s disease is a disorder of the adrenal glands. The adrenal glands are small, hat-shaped glands that sit on top of the kidneys, high up inside the back of the abdominal wall.
The adrenal glands have two functions. The inner area, called the medulla, produces the hormone adrenaline, and passes it into the bloodstream. Adrenaline increases the action of the heart and speeds up metabolism, preparing the body for shock.
The outer layer, called the cortex, produces steroids. One of the steroids it produces is cortisol, which increases the supply of glucose in the blood. Along with adrenaline, cortisol acts to help the body cope with stress. Over-production of cortisol can be harmful to the immune system. Another steroid produced by the cortex is aldosterone.
Aldosterone helps to maintain blood pressure by keeping sodium (salt) levels up in the blood. Finally, the adrenal cortex produces the male sex hormone testosterone.
In people with Addison’s disease, the adrenal cortex is destroyed, leading to a deficiency or absence of the hormones it produces.
Addison’s disease symptoms
The main symptoms of Addison’s disease are due to dehydration. They include:
- severe fatigue,
- low blood pressure,
- the need to urinate often,
- heavy brownish discoloration of the skin.
Other symptoms are constipation, muscle pain, fainting (particularly after standing up from a lying position), lack of appetite and weight loss. Recent scars may also become discoloured.
Addison’s disease is the result of the destruction of the adrenal cortex.
In about 70% of cases Addison’s disease is an autoimmune condition. This means that the destruction is caused when the body’s own immune system attacks the adrenal cortex as if it were a foreign implant. The cortex becomes inflamed (swollen) and the outer layer shrinks.
The other 30% of cases are caused by infections such as tuberculosis, tumors or other diseases of the glands.
The diagnosis is made on the severity of the symptoms and by measuring the levels of cortisol and aldosterone in the blood.
A common test to determine this is an adrenocorticotrophic hormone (ACTH) injection. ACTH controls the amount of corticosteroids that are released from the adrenal glands into the blood.
An ACTH injection would normally cause a sharp rise in the production of cortical hormones. In people with Addison’s disease there will be a very minor reaction, or no reaction at all.
Blood tests can also show low levels of sodium and sugar (hypoglycemia) in the blood and high levels of potassium, which are indicative of Addison’s disease.
Replacing the missing hormones through Hormone Replacement Therapy (HRT) can relieve the symptoms of Addison�s disease. Cortisol or prednisolone steroids may be prescribed and must be taken permanently, usually in a tablet form three times a day.
Fludrocortisone may also be prescribed to replace the hormone aldosterone.
People who have Addison�s disease and have not begun treatment for it, may be unable to cope with the stress of a surgical operation or severe injury.
A major operation or infection may cause adrenal crisis, when too much salt is lost through bleeding or sweating. Adrenal crisis can cause severe pains in the stomach, back and legs and may cause the patient to collapse. A doctor will give an injection of a steroid such as cortisone or prednisolone to treat adrenal crisis.
Because of this, it is essential that people with Addison�s disease always carry a card or wear a wristband to show the doctor, nurse or paramedic that they have the disease.