Addison's Disease

What is Addison's disease?

Addison's disease is a condition in which your adrenal glands do not make enough of certain hormones. The condition is named after a Dr Addison who first described it in 1855. Addison's disease is rare. About 8 in a million people in the UK develop it each year. Most cases are in people aged between 20 and 50, but it can occur at any age.

What are the adrenal glands and what do they do?

You have two adrenal glands. They are small glands, and lie just above each kidney. Each adrenal gland has an outer part (adrenal cortex) and an inner part (adrenal medulla). Cells in the adrenal glands make various hormones. A hormone is a chemical which is made in one part of the body but passes into the bloodstream and has effects on other parts of the body.

Cells in the adrenal cortex (the outer part of the adrenals) make the hormones cortisol and aldosterone. The amount of cortisol that is made is controlled by another hormone called adreno-cortico-trophic hormone (ACTH for short). ACTH is made in the pituitary gland (a small gland that lies just under the brain). ACTH passes into the bloodstream, is carried to the adrenal glands, and 'stimulates' the adrenal glands to make cortisol.

• Cortisol is a steroid hormone and is vital for health. It has many functions which include:
  • helping to regulate blood pressure.
  • helping to regulate the immune system.
  • helping to balance the effect of insulin in regulating the blood sugar level.
  • helping the body to respond to stress.
• Aldosterone helps to regulate salts in the bloodstream, and helps to control blood pressure.

What are the causes of Addison's disease?

Auto-immune Addison's disease
About 7 in 10 cases are due to an 'auto-immune' disease. The immune system normally makes antibodies to attack bacteria, viruses, and other 'germs'. In auto-immune diseases the immune system makes antibodies against part or patss of the body. In auto-immune Addison's disease, you make antibodies which attach to cells in the adrenal cortex. These destroy the cells which make cortisol and aldosterone. The adrenal medulla is not affected (so you still make adrenaline and noradrenaline). It is thought that something triggers the immune system to make these antibodies. The 'trigger' is not known.

If you have auto-immmune Addison's disease you have a higher than average chance of other auto-immune diseases developing such as thyroid problems, vitiligo, and pernicious anaemia.

Tuberculosis (TB)
TB is an infection which usually affects the lungs. In some cases the infection can spread to, and gradually destroy, the adrenals.

Other rare adrenal causes include:

• Other infections can sometimes affect both adrenals.
• Cancers of other parts of the body can spread and destroy the adrenals.
• Rare hereditary conditions.

'Secondary' causes of a low cortisol level
As mentioned, the amount of cortisol that you make in the adrenal glands is controlled by another hormone called ACTH. This is made in the pituitary gland. If you have low level of ACTH, your adrenals make too little cortisol. Strictly speaking, this is not a condition of the adrenals, and is not classed as Addison's disease. However, it causes similar symptoms and is called 'secondary hypoadrenalism'. Causes of a low ACTH level include:

• Some disorders and tumours of the pituitary gland which can cause a lack of ACTH (and other pituitary hormones).
• Long-term use of steroid medicines such as prednisolone. Steroid medicines are similar to cortisol. They are sometimes used to treat arthritis, cancer, and various other conditions. If you take a steroid medicine for several weeks or more, you stop making ACTH and cortisol as the steroid medicine takes over the role of cortisol. If you suddenly stop taking the steroid medicine, it takes quite some time for the pituitary and adrenal to get back into the normal making of ACTH and cortisol. Therefore, if you stop the medicine suddenly, you have no cortisol or steroid medicine equivalent. You can then quickly develop symptoms similar to an Addisonian crisis (see below).

The rest of this leaflet deals only with auto-immune Addison's disease.

What are the symptoms of auto-immune Addison's disease

In many cases the symptoms develop gradually
As the level of cortisol gradually falls you may develop one or more of the following.

• General weakness and becoming easily tired.
• Darkened areas of skin ('pigmentation'). These mainly occur on: sun-exposed areas of skin; the arm-pits; the nipples; the creases of the hands; inside the mouth; recent (rather than old) scars; pressure points such as the elbows. The cause of this is probably due to the change in hormones which can affect the pigment cells in the skin.
• Blood pressure is low and falls further when you stand which can make you dizzy.
• Being off your food and weight loss.
• Feeling sick and vomiting from time to time.
• Abdominal pains which may come and go.
• Diarrhoea or constipation which may come and go.
• Cramps and pains in muscles.
• Craving for salt, or salty foods and drinks.
• Menstrual periods in women may become irregular, or stop.

The symptoms can be vague at first. For example, you may feel tired and 'not right', but it is difficult to say why. Also, most of the symptoms can be caused by other problems, and Addison's disease is rare. So, the condition may not be recognised for weeks or months after symptoms first begin.

Acute (sudden) symptoms develop in some cases - an Addisonian crisis
If the level of cortisol quickly falls very low you can become very ill in a short time. This is called an 'Addisonian crisis'. In this situation symptoms include: severe vomiting and diarrhoea, pains in the back and abdomen, dehydration, low blood pressure, and collapse. You may become severely ill and may die if the cause of the symptoms is not diagnosed and treated quickly.

An Addisonian crisis may suddenly develop after a period of less severe symptoms (described above). The 'crisis' is often triggered by another illness such as an infection, or a stress such as a surgical operation. During these times your body needs extra cortisol. But, if you have Addison's disease you cannot make extra cortisol, and you may then quickly develop these crisis symptoms. In some cases an Addisonian crisis develops without having had any previous symptoms.

What tests are needed?

A one-off measurement of blood cortisol is not good enough to diagnose Addison's disease. It may be low from time to time in normal people. Therefore, if Addison's disease is suspected, a special stimulation test is usually needed to confirm the diagnosis. The adrenal gland can be 'stimulated' by an injection of a drug similar to ACTH. If the adrenals are normal, then blood samples taken shortly after this injection should show a rise in cortisol. If you have Addison's disease you do not have a rise in blood cortisol following the injection. Also, a blood test can sometimes detect antibodies which cause auto-immune Addison's disease.

(Other tests may be needed if it is thought that you have Addison's disease caused by other conditions such as TB, or a secondary cause of a low ACTH and cortisol level.)

What is the treatment for Addison's disease

Cortisol replacement
You need steroid medication to replace the cortisol which you no longer make. This is usually with a medicine called hydrocortisone which is very similar to cortisol. The dose is usually about 20 mg first thing in the morning and 10 mg at 6 pm. Some people need more than this, and others less.

If you have an illness such as an infection, or an accident, or anything else causing major stress such as an operation, you should double the dose. If you vomit and cannot take medication by mouth, you should have the hydrocortisone by injection. You should never miss a dose.

You are strongly advised to wear a bracelet, necklace or similar which can alert people that you need hydrocortisone in case of emergencies. For example, if you are knocked out in a car crash and are not able to tell the doctor that you have Addison's disease. Apart from any other treatment you will always need your hydrocortisone (or similar steroid replacement for cortisol).

Replacing aldosterone
Fludrocortisone is a substitute medicine for aldosterone. This helps to regulate blood pressure and blood salt level. You may also be advised to take extra salt each day.

If you have an Addisonian crisis
This is a medical emergency. You will be given hydrocortisone injections, a 'drip' of fluid to bring up your blood pressure, and may need intensive care until the crisis is over, You will then need to continue taking hydrocortisone medication as detailed above.

Further help and advice

Addison's Disease Self Help Group
Web: www.addisonsdisease.org.uk
The group offers advice, information, newsletters and contact with fellow group members.

MedicAlert Foundation
1 Bridge Wharf, 156 Caledonian Road, London, N1 9UU
Tel: 0800 581 420    Web: www.medicalert.co.uk
Medic-alert bracelets are often worn by people where emergencies may possibly arise (such as people with diabetes, severe allergies, Addison's disease, epilepsy, etc).

© EMIS and PIP 2006   Updated: November 2006