In about 75% of cases, yes. Addison’s disease is most commonly caused by the immune system attacking the adrenal glands, the small hormone-producing organs that sit on top of your kidneys. This autoimmune form is so dominant in developed countries that “Addison’s disease” and “autoimmune adrenal insufficiency” are often used interchangeably, though other causes do exist.
How the Immune System Damages the Adrenals
Your adrenal cortex, the outer layer of each adrenal gland, is organized into three distinct zones, each responsible for producing different hormones: cortisol (which regulates stress, metabolism, and inflammation), aldosterone (which controls blood pressure and salt balance), and small amounts of sex hormones. In autoimmune Addison’s, immune cells gradually infiltrate and destroy all three zones.
The primary target is an enzyme called 21-hydroxylase, which the adrenal cortex needs to manufacture its hormones. For reasons that aren’t fully understood, the immune system misidentifies this enzyme as a threat. A specific type of immune cell, CD8+ T cells, zeroes in on 21-hydroxylase and destroys the cells that contain it. Over time, the gland shrinks, becomes fibrotic, and loses its ability to produce hormones altogether.
Blood tests can detect antibodies against 21-hydroxylase, and these serve as the main biomarker for confirming the autoimmune form. These antibody tests are highly accurate, with a sensitivity of 100% and a specificity of 98% in clinical studies. Importantly, the antibodies often show up years before any symptoms appear, which opens a window for monitoring people at high risk.
The Slow Progression Before Symptoms Appear
Autoimmune Addison’s doesn’t happen overnight. The destruction follows a predictable sequence that can unfold over months or years. After 21-hydroxylase antibodies appear in the blood, the first measurable change is a rise in renin, a signal that aldosterone production is starting to falter and the body is struggling to maintain blood pressure and sodium levels. Next, the adrenal glands begin losing their ability to ramp up cortisol production under stress, even though resting cortisol levels may still look normal. Eventually, baseline cortisol drops and the pituitary gland compensates by flooding the system with its stimulating hormone (ACTH), trying to force the damaged adrenals to work harder.
By the time someone shows up with classic symptoms, roughly 90% of the adrenal cortex has already been destroyed. This is why Addison’s disease is frequently diagnosed late, often during a crisis triggered by illness, injury, or surgery that demands a cortisol surge the body can no longer deliver.
What Non-Autoimmune Addison’s Looks Like
The remaining 25% of cases have other causes. Globally, tuberculosis is still a leading one, particularly in regions where TB remains common. The infection can spread to the adrenal glands and destroy them in much the same way autoimmunity does, just through a different mechanism. Other causes include fungal infections, cancer that has metastasized to the adrenals, bleeding into the adrenal glands (adrenal hemorrhage), certain genetic conditions, and rare infiltrative diseases. Some medications that block cortisol production can also trigger adrenal insufficiency, though this is typically reversible.
The clinical picture is largely the same regardless of cause: fatigue, weight loss, low blood pressure, salt cravings, darkening of the skin, and in severe cases, life-threatening adrenal crisis. The distinction matters mainly for treatment planning and for understanding whether related autoimmune conditions might also develop.
Addison’s Rarely Travels Alone
When Addison’s disease is autoimmune, it frequently clusters with other autoimmune conditions. This grouping is recognized formally as autoimmune polyendocrine syndrome, which comes in two main types.
Type 1 typically begins in childhood and involves at least two of three hallmark conditions: chronic fungal infections of the skin and mucous membranes, underactive parathyroid glands, and Addison’s disease. It can also include premature ovarian failure (affecting about 60% of women with this syndrome before age 30), chronic diarrhea, liver inflammation, and problems with tooth enamel. This type is caused by a single gene mutation and is relatively rare.
Type 2 is far more common and tends to appear in adulthood. It involves Addison’s disease alongside type 1 diabetes, autoimmune thyroid disease (usually Hashimoto’s), or both. Many people with Type 2 also develop celiac disease, vitiligo, hair loss, or pernicious anemia. If you’ve been diagnosed with autoimmune Addison’s, your doctor will typically screen for these related conditions, since having one autoimmune disease raises your risk of developing others.
How Rare Is Addison’s Disease?
Addison’s disease affects between 4 and 11 people per 100,000, with roughly 0.6 new cases diagnosed per 100,000 people each year. It can occur at any age but is most commonly diagnosed in adults between 30 and 50. Women are affected slightly more often than men, which tracks with the general pattern of autoimmune diseases being more prevalent in women.
Despite its rarity, Addison’s disease carries significant consequences if unrecognized. People with confirmed autoimmune Addison’s require lifelong hormone replacement to substitute for the cortisol and aldosterone their adrenals can no longer make. With consistent treatment, most people live full, active lives, though they need to adjust their medication during illness or physical stress to prevent adrenal crisis.