What is Addison's Disease?

The adrenal glands are two small, triangular organs situated above the kidneys that produce the hormones that keep the body functioning correctly. They are part of the endocrine system and influence almost all the organs and tissues in the human body. The hormones these glands produce help the immune system, play a role in the stress response, maintain normal blood pressure, and balance salt and water throughout the body. Two of these important hormones are cortisol and aldosterone.

Addison's disease occurs when the adrenal glands are harmed or injured, often when the immune system attacks the adrenal cortex. This is usually a result of an autoimmune disease, although it can also be caused by tuberculosis, genetic defects, surgical removal of the adrenal glands, or cancer or infection of, or bleeding into, the glands. Any of these factors can affect the glands' ability to produce hormones. Such causes result in a diagnosis of primary adrenal insufficiency.

Hormones produced in the pituitary gland prompt production of hormones in the adrenal glands. Damage to the pituitary gland can prevent the adrenal glands from working properly, as they are not receiving the correct messages telling them how to function. This is secondary adrenal insufficiency; pituitary inflammation, tumors, or surgery can cause it. A reversible type of secondary adrenal insufficiency can result from sudden withdrawal from corticosteroids, prescribed for conditions such as asthma and arthritis.

The symptoms of Addison's disease develop slowly and are often mistaken for other conditions in the early stages, such as the flu or depression. This can result in an individual ignoring their symptoms and putting off treatment. People with Addison's disease may experience

• salt cravings
• low blood sugar
• fainting
• fatigue and exhaustion
• weight loss and loss of appetite
• depression and irritability
• joint and muscle pains
• darkened skin
• increased thirst
• dizziness
• cramps and abdominal pain

Diagnostic tests for Addison's include determining the amount of sodium, cortisol, potassium, and adrenocorticotropic hormone (ACTH) in the blood, through blood tests and other methods. CT and MRI scans can assess the adrenal glands. If the doctor suspects secondary adrenal insufficiency, she may also record the level of insulin in the blood. Most of the time, an endocrinologist performs these diagnostic tests.

Lifelong medications are the most common treatment for Addison's disease — corticosteroid replacement therapy requires tablets taken two or three times each day. Unfortunately, constant use of corticosteroids can cause side effects such as osteoporosis and reduced immunity, so doctors take great care to prescribe the minimum required dose and monitor their patients closely.

People with Addison's disease must take their prescribed medication and attend regular appointments with an endocrinologist. Wearing a medical alert bracelet can inform medical staff of one's condition in the event of an emergency. Some people with Addison's also carry an emergency kit to be prepared should a crisis occur.

People with Addison's disease are at risk of acute adrenal failure or Addisonian crisis, a medical emergency caused by severe adrenal insufficiency. It is potentially fatal and individuals experiencing the event require hospitalization and an injection of hydrocortisone. Symptoms include:

• confusion
• pain in the legs or lower back
• severe muscle weakness
• severe dehydration
• loss of consciousness or severe drowsiness
• headache
• vomiting and diarrhea
• sweating
• clammy and pale skin

Addison's is rare, affecting around one in 100,000 people in the United States, and approximately 40 to 60 million people worldwide. Determining an exact number is challenging as some people are not accurately diagnosed. The condition seems to affect both sexes equally and can develop at any age, though the majority of diagnoses are in people between the ages of 30 and 50.

The first person to describe Addison's disease was a British doctor, Thomas Addison, in 1855. He called it "melasma suprarenale" after noting it in a number of patients with tuberculosis. Though the disease was initially fatal due to a lack of hormone-replacement drugs, between the 1930s and 1950s, cortisone was made available as a medical treatment to replace the missing cortisol.