Addison's disease and adrenal insufficiency explained

What the adrenal glands do

The two adrenal glands are small but vital, producing hormones that keep the body running smoothly. The most important is cortisol, which helps control blood sugar, blood pressure and the way the body responds to stress and illness. The glands also make aldosterone, which helps balance salt and water and keep blood pressure steady, and a share of the body's sex hormones. Cortisol levels naturally rise and fall through the day and climb sharply when we are unwell or under strain, which is the body's way of coping with challenge. When the adrenal glands cannot make enough of these hormones, the body loses this vital support system, and even ordinary illnesses become harder to weather safely.

What Addison's disease is

Addison's disease, also called primary adrenal insufficiency, happens when the adrenal glands themselves are damaged and can no longer make enough cortisol and usually aldosterone. In the UK the most common cause is the immune system mistakenly attacking the glands, an autoimmune process. There is also a separate, more common situation called secondary adrenal insufficiency, where the problem lies not in the adrenal glands but in the pituitary gland in the brain that instructs them, or from suddenly stopping long-term steroid medicines. Whatever the cause, the result is too little cortisol, and the body struggles to maintain energy, blood pressure and blood sugar, and cannot mount the extra cortisol needed during illness, injury or other physical stress.

Recognising the symptoms

The symptoms of adrenal insufficiency often develop slowly and can be vague, which is why the condition is sometimes missed at first. Common features include persistent tiredness and weakness, loss of appetite and weight, low mood, dizziness on standing from low blood pressure, and craving salty foods. A distinctive sign in Addison's disease is darkening of the skin, which can look like a tan on areas not usually exposed to the sun, such as scars, skin creases and the inside of the mouth. Because these symptoms overlap with many everyday complaints, diagnosis can be delayed until a person becomes seriously unwell. Blood tests measuring hormone levels, sometimes with a special stimulation test, confirm the diagnosis, so persistent unexplained tiredness and weight loss deserve investigation.

Treatment and daily management

The good news is that adrenal insufficiency is very treatable. Because the body cannot make enough of its own hormones, treatment replaces them with steroid medicines taken every day, usually to replace cortisol and, in Addison's disease, often aldosterone as well. Taken correctly, this replacement allows most people to live full, active lives. The crucial part is learning the sick-day rules: when unwell, feverish, injured or having an operation, the body would normally make extra cortisol, so people need to increase their steroid dose to match. Everyone with the condition is advised to carry a steroid emergency card and wear medical identification, and to have an emergency injection kit at home. Regular review with a specialist team helps keep replacement balanced and reinforces this vital self-management.

Adrenal crisis: a medical emergency

An adrenal crisis is a life-threatening emergency that happens when the body runs critically short of cortisol, often triggered by infection, injury, vomiting, an operation, or missing steroid doses. Warning signs include severe weakness, dizziness or fainting, very low blood pressure, severe vomiting and diarrhoea, confusion or drowsiness, and collapse. This is a 999 emergency: it needs urgent steroid treatment and fluids without delay, and can be fatal if not treated quickly. People with the condition and their families are taught to give an emergency steroid injection and to call 999, telling the ambulance crew the person has adrenal insufficiency and may be in adrenal crisis. This article is for education only and cannot diagnose you — if you suspect an adrenal crisis, call 999 immediately.