Addison’s disease

What is it?

Addison’s disease (also known as primary adrenal insufficiency) occurs when something damages the adrenal glands, and disrupts the production of corticosteroid hormones there. Consequently, insufficient amounts of these hormones are available, which results in disturbances in body chemistry and leads to a wide range of symptoms.

These corticosteroid hormones include:

• Aldosterone - regulates salt and water loss through the kidneys and so helps control blood pressure and fluid levels in the body.
• Cortisol (or hydrocortisone) and corticosterone – these affect almost every cell in the body. Their main job is to help the body deal with stress of any form, maintain glucose or sugar levels in the blood, control blood pressure, keep a check on inflammation within the body and regulate the metabolism of fats, carbohydrates and proteins.
• Male and female sex hormones - testosterone and oestrogen are produced in small amounts by the adrenal glands.

What causes it?

In around 70 per cent of cases, Addison’s disease is believed to occur when the body’s immune system attacks its own adrenal glands for some unknown reason. This is called an autoimmune reaction.

Other causes include tuberculosis, HIV, cancer and other diseases of the adrenal glands.

Addison’s disease affects between one and four of every 100,000 people, so it’s rare.

What are the symptoms?

Symptoms of adrenal failure don’t usually appear until about 90 per cent of the adrenal tissue has been damaged. Onset may be slow, often over weeks or months, and symptoms are usually vague and variable at first, so it can be years before the condition is diagnosed.

People with Addison’s disease may feel increasingly weak, lethargic, lose their appetite and weight, and may suffer recurrent abdominal pain and vomiting.

Other symptoms include:

• Falling blood pressure (especially on standing up quickly).
• Nausea.
• Vomiting.
• Diarrhoea.
• Irritability.
• Depression.
• Changes in salt levels (rising blood potassium levels and falling sodium levels in the blood) which can cause a craving for salty foods.
• Headache.
• Sweating.
• Irregular or absent periods in women.

A characteristic feature of Addison’s disease is a change in pigmentation on certain parts of the body. Skin creases of the palms, knuckles, elbows and knees may darken, becoming brownish in colour (hyperpigmentation). The inside of the mouth may also darken.

If the demand for corticosteroid hormone rapidly outstrips the ability of the glands to produce it, an Addisonian crisis (or acute adrenal insufficiency) may occur. This most typically occurs when someone with Addison’s is put under extra stress, for example during illness or surgery, and urgently needs increased amounts of adrenal hormones.

During an Addisonian crisis, symptoms rapidly worsen and may include

• Dehydration.
• Confusion.
• Weakness.
• Vomiting.
• Severe abdominal pain resulting from excessive loss of salt and water.

It can lead to coma and even death unless treated quickly.

An Addisonian crisis may be the first obvious sign that alerts doctors to a diagnosis of Addison’s disease.

What’s the treatment?

The diagnosis of Addison’s disease must first be confirmed with blood tests to determine whether levels of adrenal hormones are insufficient and then further investigations to try to establish the cause.

The most commonly used test is the ACTH stimulation test which measures levels of cortisol in the blood and urine after a dose of a synthetic stimulating hormone ACTH has been given to prompt the adrenals into action. People with Addison’s disease show little or no response to this. During an Addisonian crisis, symptoms may provide a strong clue to the diagnosis but formal testing will have to wait until the affected person has been treated.

When possible, the underlying cause of the Addison’s disease should then be treated.

Treatment of Addison’s itself simply involved replacing or substituting the hormones that aren’t being produced in sufficient quantities by the adrenal glands. For example, synthetic oral corticosteroid drugs such as prednisone can be taken to cortisol, and a drug called fludrocortisone can be taken to replace aldosterone.

Occasionally, the dose of treatment may need to be increased, such as during times of infection or other stress. Patients with Addison’s are always given clear advice about these issues, about the importance of always letting a doctor or dentist know they’re taking steroid medication, and not to stop treatment suddenly.

People with Addison’s disease are encouraged to carry a steroid card or wear an identification bracelet so people know they’re taking steroid therapy if problems arise.

With treatment and regular specialist monitoring, people with Addison’s disease can expect to live long and active lives.

BBC Health