Addison's Disease (Adrenal Insufficiency)

Addison's disease is a form of adrenal insufficiency, meaning the adrenal glands do not make enough of certain essential hormones. Cortisol and, often, aldosterone fall too low, which affects energy, blood pressure, and the body's salt balance. Symptoms can be vague at first, so blood tests are central to recognising it.

What Addison's disease is

The adrenal glands are two small glands that sit on top of the kidneys. Each has an outer layer, the cortex, that produces several steroid hormones, including cortisol and aldosterone. Cortisol helps regulate blood sugar, blood pressure, the immune response, and the way the body copes with stress and illness; its release follows a daily rhythm, peaking in the morning. Aldosterone helps the body balance sodium, potassium, and fluid, which in turn supports blood pressure and hydration.

In Addison's disease, the adrenal cortex itself is damaged and produces too little of these hormones. This is called primary adrenal insufficiency. There is also a secondary form, in which the adrenal glands are structurally intact but the pituitary gland does not release enough adrenocorticotropic hormone (ACTH) to stimulate them; in this form aldosterone is usually less affected because it is controlled mainly by a separate system. The hormone patterns differ between the two, which helps clinicians tell them apart. A sudden, severe shortage of cortisol — sometimes triggered by illness, injury, or stress — is a medical emergency known as an adrenal crisis.

This comparison is illustrative and simplified; a clinician interprets the full pattern of tests and symptoms to reach a diagnosis.

Common signs and symptoms

Symptoms usually develop slowly and can be easy to overlook, because each one is common and non-specific on its own. They may include:

• Persistent tiredness and weakness
• Loss of appetite and unintentional weight loss
• Low blood pressure, sometimes with dizziness or light-headedness on standing
• Nausea, vomiting, or abdominal discomfort
• Salt cravings
• Darkening of the skin, particularly in primary adrenal insufficiency, often most visible in skin creases, scars, and the gums
• Low mood and irritability
• Muscle or joint aches

Because symptoms come on gradually and overlap with many everyday complaints, the condition can go unrecognised for a time. Sometimes it is first suspected during an illness that unmasks the shortage of cortisol, when the body is unable to mount the extra cortisol it would normally produce to cope. The skin darkening seen in primary disease can be a useful clue, since it reflects the high levels of the signalling hormone ACTH that accompany a failing adrenal cortex.

What causes it

The most common cause of primary adrenal insufficiency in many regions is an autoimmune process, in which the immune system mistakenly attacks the adrenal cortex. This can occur on its own or alongside other autoimmune conditions. Other causes include certain infections that damage the adrenals, bleeding into the glands, cancer that has spread to them, surgical removal, and some inherited or genetic conditions affecting adrenal hormone production.

Secondary adrenal insufficiency often relates to problems with the pituitary gland, such as a tumour, its treatment, or injury that reduces ACTH output. A separate and common situation is the suppression of the body's own cortisol production that can follow prolonged use of glucocorticoid medicines (steroids); if these are stopped abruptly, the adrenal glands may not yet have resumed adequate output. This is why glucocorticoid medicines should only be changed under medical guidance, and why people taking them long term are often counselled about it.

How it is diagnosed

Diagnosis combines symptoms and history with blood tests that assess cortisol and the signals controlling it. Because cortisol follows a daily rhythm, timing matters, and a dynamic (stimulation) test is often needed rather than a single measurement. Common tests include:

• Morning cortisol — a low morning level raises suspicion of insufficiency, while a robustly normal level makes it less likely.
• ACTH — helps distinguish primary from secondary forms; it is typically high in primary disease as the pituitary tries to stimulate failing glands.
• An ACTH stimulation test — measures how cortisol responds to a dose of synthetic ACTH, and is a key confirmatory test.
• Electrolytes — sodium and potassium can be abnormal, especially when aldosterone is low.
• Antibody and other tests — to look for an autoimmune or other underlying cause, sometimes with imaging.

For background on the cortisol test, see the source below and our blood tests and hormones sections.

How it is generally managed

Addison's disease is generally managed by replacing the hormones the adrenal glands can no longer make adequately, under the ongoing care of a clinician. Because cortisol is essential, replacement of glucocorticoid is central, and many people with primary disease also need replacement of the salt-balancing (mineralocorticoid) hormone. Replacement is lifelong in established primary disease, since the glands do not recover. This page does not give doses, which are individualized by a clinician.

Ongoing treatment matters because the body cannot compensate on its own; missed or inadequate replacement can allow symptoms to return and, in some circumstances, can lead toward a crisis. Because the body normally produces more cortisol during illness, injury, surgery, or other stress, people with adrenal insufficiency are usually taught about temporarily adjusting their care at such times under medical guidance — sometimes called "sick-day" guidance — and about recognising the early warning signs of an adrenal crisis. Many carry an emergency card or alert and are advised about an emergency plan.

An adrenal crisis is a medical emergency that requires urgent treatment without delay; it is not something to manage at home. With appropriate, consistent replacement and regular review, many people with the condition are able to lead full, active lives. General treatment principles are described in our treatments section, and you can read related material in our conditions overview. This page is educational and is not a substitute for personalised medical advice.