What is it?
Adrenal insufficiency is a disorder characterised by underactive adrenal glands and an insufficient production of the hormones cortisol and, sometimes, aldosterone. The adrenal glands are small organs located on top of each kidney. They consist of an inner layer called the medulla and an outer layer called the adrenal cortex. In the body, the hypothalamus, the pituitary glands, and the adrenal glands work together to produce hormones that control many body systems. If any part of their signaling and feedback systemis not working it can cause major disruptions and illness within the body.
Cortisol is a glucocorticoid hormone, produced by the adrenal cortex. Among its many roles, cortisol affects the metabolism of carbohydrates, proteins, and fats, affects glucose levels in the blood, acts as an anti-inflammatory agent, and helps the body react to stress. Aldosterone, a mineralocorticoid hormone that is also produced by the adrenal cortex, manages the salt and potassium balance in the blood. Without enough of these two hormones, the body becomes weak and dehydrated, unable to maintain an adequate blood pressure or to respond properly to stress.
Adrenal insufficiency affects about 1-4 people per 100,000. It is found in patients of all ages and affects both males and females equally. Addison’s disease is a term used as a synonym for primary adrenal insufficiency, caused by damage to the adrenal cortex; it does not present itself until 80 - 90% has been destroyed. The term “Addison’s disease” is often used incorrectly to refer to both primary and secondary adrenal insufficiency.
About 70% of primary adrenal insufficiency is due to an autoimmune process. About 30% of the time the adrenal damage is due to other causes, such as: tuberculosis (a common cause in areas of the world where tuberculosis is more prevalent); bacterial, viral and fungal infections; adrenal haemorrhage; and the spread of cancer into the adrenal glands. Rarely, it may be due to a genetic abnormality of the adrenal glands.
Secondary adrenal insufficiency is due to a decrease in the production of the pituitary hormone ACTH (adrenocorticotropic hormone). ACTH is a pituitary messenger - it tells the adrenal cortex to produce cortisol. If there is insufficient ACTH - due to pituitary damage, a pituitary tumour, or some other cause -- then cortisol production is not stimulated. Secondary adrenal insufficiency can also arise when corticosteroid therapy (such as prednisone, which may be given to relieve inflammation in conditions such as rheumatoid arthritis) is abruptly halted. These treatments suppress natural cortisol production and it can take several weeks or months for normal production to resume. With secondary adrenal insufficiency aldosterone production is usually not affected.