In people with Addison's disease, these glands become damaged and don't work effectively, so insufficient amounts of these important hormones are produced. This can be life-threatening if untreated.
It's well-known for being difficult to diagnose as the main symptoms of fatigue, weakness and weight loss are also common in other conditions.
In 70 to 90 per cent of cases, Addison's develops because of a problem with your immune system. In autoimmune Addison's disease, your body mistakenly produces antibodies which attach themselves to cells in your adrenal glands. They then destroy the cells which are responsible for making cortisol and aldosterone.
Tuberculosis (TB) used to be the commonest cause of Addison's in the UK and in areas of the world where this disease is still widespread, TB continues to be the main cause.
In rare cases, an infection can affect the adrenal glands, such as meningitis or HIV.
Addison's can be hard to spot early as signs are similar to those of many other conditions. Over half of sufferers have symptoms for over a year before they are diagnosed, and 60 per cent had seen two or more doctors before diagnosis.
Signs include: tiredness; weight loss; muscle weakness; dizziness; increased thirst; darkened areas of skin pigmentation; feeling or being sick; diarrhoea or constipation; craving salty foods; low blood pressure; and irregular periods.
You can become very unwell quickly with Addison's if levels of cortisone drop very low – this is known as an Addisonian crisis. In these cases, symptoms include severe sickness and diarrhoea, pain in your tummy and back, low blood pressure, dehydration and collapse. This is a medical emergency needing urgent treatment in hospital.
Your doctor will examine your skin for signs of darker pigmentation, especially on scars, lips and gums, and in skin creases. About 95 per cent of Addison's sufferers have these signs.
Blood tests are carried out to measure your levels of cortisol – a level below 83 nanomoles is likely to indicate Addison's. Levels of potassium and sodium are also measured. A low sodium and high potassium reading can indicate Addison's.
You might be referred to an endocrinologist (hormone specialist) for more tests. These might include tests to measure your levels of aldosterone, adrenocorticotrophic hormone (ACTH), your sugar levels and a test to look for antibodies that attack the adrenal glands.
If these tests indicate you may have Addison's, a further test called a Synacthen® Stimulation test is done to confirm diagnosis. This involves giving you an injection of man-made ACTH to watch how your adrenal glands respond. It should stimulate a rise in cortisol and if it doesn't then Addison's is likely.
Who gets it?
It is a relatively rare condition, affecting around 8,400 people in the UK. While it can affect you at any age, it's most common in 30 to 50 year olds and affects women more than men.
People who develop Addison's often have other immune system conditions, such as type 1 diabetes, hypothyroidism and coeliac disease.
Once diagnosed with Addison's, you will need lifelong hormone replacement drug treatment to control it, supervised by an endocrinologist.
Glucocorticoid and mineralocorticoid replacement drugs are prescribed. Glucocorticoid, in the form of hydrocortisone tablets, is normally given in 15 to 25mg doses three times daily.Mineralocorticoid, in the form of fludrocortisone, is given as a 50 to 300mcg dose daily.
Your specialist will tell you about increasing your medication when you are unwell with an infection, injury or before an operation.
Some research studies have found that taking vitamin D supplements may help reduce the severity of the disease as well as helping to prevent autoimmune conditions.
Other useful supplements to ease symptoms include: 5-HTP to combat stress, a known trigger of Addison's crises; Panax ginseng for fatigue; and magnesium for stress and fatigue.