Causes - Addison's disease

Addison's disease develops when the outer layer of your adrenal glands (adrenal cortex) is damaged, reducing the levels of hormones it produces.

Problems with the immune system

The immune system is your body’s defence against infection and disease. If you're ill, your immune system produces antibodies. Antibodies are a special type of protein that destroys disease-carrying organisms and toxins. These antibodies attack the cause of the illness.

But, if you develop a problem with your immune system, it can start to attack your own healthy tissues and organs. This is known as an autoimmune disorder.

Addison’s disease can develop if your immune system attacks your adrenal glands and severely damages your adrenal cortex. When 90% of the adrenal cortex is destroyed, your adrenal glands won't be able to produce enough cortisol and aldosterone. These are steroid hormones,. Once levels start decreasing, you'll experience symptoms of Addison’s disease.

It's not clear why some people develop this problem with their immune system but it can run in families.

Genetics and Addison's disease

Some people with certain genes are more likely to develop autoimmune disorders.

Your risk of developing Addison's disease is increased if you or a close family member have another autoimmune condition.

For example:

• vitiligo – a chronic (long-term) condition that causes pale, white patches to develop on the skin
• type 1 diabetes – a chronic condition caused by too much glucose in the blood
• underactive thyroid gland (hypothyroidism)

Other causes of Addison's disease

Tuberculosis (TB) is the most common cause of Addison's disease worldwide, but it is rare in Ireland.

TB is a bacterial infection that mostly affects the lungs, but can also spread to other parts of your body. It can cause Addison’s disease if it damages your adrenal glands.

There are other possible causes of Addison’s disease.

Infections

Infections such as those linked to AIDS, or fungal infections.

Heavy bleeding

Very heavy bleeding (haemorrhage) into the adrenal glands. This is sometimes associated with meningitis or other types of severe sepsis.

Cancer

If cancer cells from elsewhere in your body spread to your adrenal glands.

Amyloidosis

Amyloidosis is a disease where amyloid, a protein produced by your bone marrow cells, builds up in your adrenal glands and damages them.

Adrenalectomy

Adrenalectomy is the surgical removal of both adrenal glands. This may be done to remove a tumour.

Adrenoleukodystrophy (ALD)

Adrenoleukodystrophy (ALD) is a rare, life-limiting, inherited condition. It affects the adrenal glands and nerve cells in the brain. ALD most often affects young boys.

Cushing's syndrome treatment

Cushing's syndrome is a collection of symptoms caused by very high levels of cortisol in the body. Certain treatments needed for Cushing's syndrome are a possible cause of Addison's disease.

Secondary adrenal insufficiency

The production of hormones from the adrenal gland can also be affected by damage to the pituitary gland. The pituitary gland is a pea-sized gland located below the brain. It produces a hormone that stimulates the adrenal gland. This is a separate condition to Addison's disease, known as secondary adrenal insufficiency.

Secondary adrenal insufficiency can occur if your pituitary gland becomes damaged. For example, because of a tumour on the pituitary gland (known as pituitary adenomas).