Causes

Addison's disease is caused by damage to your adrenal glands, resulting in not enough of the hormone cortisol and, often, not enough aldosterone as well. Your adrenal glands are part of your endocrine system. They produce hormones that give instructions to virtually every organ and tissue in your body.

Your adrenal glands are composed of two sections. The interior (medulla) produces adrenaline-like hormones. The outer layer (cortex) produces a group of hormones called corticosteroids. Corticosteroids include:

• Glucocorticoids. These hormones, which include cortisol, influence your body's ability to convert food into energy, play a role in your immune system's inflammatory response and help your body respond to stress.
• Mineralocorticoids. These hormones, which include aldosterone, maintain your body's balance of sodium and potassium to keep your blood pressure normal.
• Androgens. These male sex hormones are produced in small amounts by the adrenal glands in both men and women. They cause sexual development in men, and influence muscle mass, sex drive (libido) and a sense of well-being in both men and women.

Primary adrenal insufficiency

When the cortex is damaged and doesn't produce enough adrenocortical hormones, the condition is called primary adrenal insufficiency. This is most commonly the result of the body attacking itself (autoimmune disease). For unknown reasons, your immune system views the adrenal cortex as foreign, something to attack and destroy. People with Addison's disease are more likely than others to have another autoimmune disease as well.

Other causes of adrenal gland failure may include:

• Tuberculosis
• Other infections of the adrenal glands
• Spread of cancer to the adrenal glands
• Bleeding into the adrenal glands. In this case, you may have an addisonian crisis without any previous symptoms.

Secondary adrenal insufficiency

The pituitary gland makes a hormone called adrenocorticotropic hormone (ACTH). ACTH in turn stimulates the adrenal cortex to produce its hormones. Benign pituitary tumors, inflammation and prior pituitary surgery are common causes of not producing enough pituitary hormone.

Too little ACTH can lead to too little of the glucocorticoids and androgens normally produced by your adrenal glands, even though your adrenal glands themselves aren't damaged. This is called secondary adrenal insufficiency. Mineralocorticoid production is not affected by too little ACTH.

Most symptoms of secondary adrenal insufficiency are similar to those of primary adrenal insufficiency. However, people with secondary adrenal insufficiency don't have hyperpigmentation and are less likely to have severe dehydration or low blood pressure. They're more likely to have low blood sugar.

A temporary cause of secondary adrenal insufficiency occurs when people who take corticosteroids (for example, prednisone) to treat chronic conditions, such as asthma or arthritis, stop taking the corticosteroids all at once rather than tapering off.