Addison's disease: Causes, symptoms, diagnosis and treatment
What Is Addison's disease?
Addison’s disease, primary adrenal insufficiency or hypoadrenalism, is a condition affecting the adrenal glands.
A person with Addison’s disease doesn't produce enough of two important hormones - cortisol and aldosterone.
Symptoms of Addison’s disease include fatigue, muscle weakness, low mood, loss of appetite, unexpected weight loss, and being thirstier than usual.
The condition is rare, affecting around 8,400 people in the UK.
Cortisol and aldosterone
Cortisol's most important function is to help the body respond to stress. It also helps regulate your body's use of protein, carbohydrates, and fat; helps maintain blood pressure and cardiovascular function; and control inflammation. Aldosterone helps your kidneys regulate the amount of salt and water in your body - the main way you keep your blood pressure under control. When aldosterone levels drop too low, your kidneys cannot keep your salt and water levels in balance. This makes your blood pressure drop.
There are two forms of Addison's disease. If the problem is with the adrenal glands themselves, it's called primary adrenal insufficiency. If the adrenal glands are affected by a problem starting somewhere else - such as the pituitary gland - it's called secondary adrenal insufficiency.
What causes Addison's disease?
When Addison's disease is the result of a problem with the adrenal glands themselves, it is called primary adrenal insufficiency. About 70% of the time, this happens because the body's self-defence mechanism - the immune system - mistakenly attacks the adrenal glands. This so-called "autoimmune" attack destroys the outer layer of the glands.
Long-lasting infections - such as tuberculosis, HIV, and some fungal infections - can harm the adrenal glands. Cancer cells that spread from other parts of the body to the adrenal glands can also cause Addison's disease.
Less commonly, Addison's disease is not due to the failure of the adrenal glands themselves. This condition, secondary adrenal insufficiency, can be caused by problems with the hypothalamus or pituitary gland, located in the centre of the brain. These glands produce hormones that act as a switch and can turn on or off the production of hormones in the rest of the body. A pituitary hormone called ACTH is the switch that turns on cortisol production in the adrenal gland. If ACTH levels are too low, the adrenal glands stay in the off position.
Another cause of secondary adrenal insufficiency is prolonged or improper use of steroid hormones such as prednisolone. Less common causes include pituitary tumours and damage to the pituitary gland during surgery or radiotherapy.
What are the symptoms of Addison's disease?
Over time, Addison's disease leads to these symptoms:
- Chronic fatigue and muscle weakness
- Loss of appetite, inability to digest food, and weight loss.
- Low blood pressure (hypotension) that falls further when standing. This makes a person dizzy, sometimes to the point of fainting
- Blotchy, dark tanning and freckling of the skin. This is most noticeable on parts of the body exposed to the sun, but also occurs in unexposed areas. Darkened skin is particularly likely to occur on the forehead, knees and elbows or along scars, skin folds, and creases (such as on the palms)
- Blood sugar abnormalities, including dangerously low blood sugar (hypoglycaemia)
- Nausea, vomiting, and diarrhoea
- Inability to cope with stress
- Moodiness, irritability, and depression
- Increased thirst
- Craving of salty foods
Some of these symptoms may indicate conditions other than Addison's disease. If you experience any of the symptoms, talk with your doctor about whether Addison's disease or another condition may be the cause.
Because symptoms of Addison's disease progress slowly, they may go unrecognised until a physically stressful event, such as another illness, surgery, or an accident. All of a sudden, the symptoms may get much worse. When this happens, it's called an Adrenal crisis (Addisonian crisis). For one in four people with Addison's disease, this is the first time they realise they are ill. An adrenal crisis is considered a medical emergency because it can be fatal.
Symptoms of an adrenal crisis include:
- Extreme muscle weakness and headache
- Severe vomiting and diarrhoea, followed by severe dehydration
- Severe low blood pressure
- Extreme sleepiness or loss of consciousness