Addison’s disease, named after the doctor who first described it more than one hundred years ago, occurs when the adrenal cortex, the outer part of the adrenal glands above the kidneys, is destroyed and no longer produces hormones. Before we knew about adrenocortical hormones, cortisone, and the related steroid hormones, Addison’s disease was always fatal, although a person with the condition could live for years.
In the old days, destruction of the adrenal cortex was usually due to tuberculosis, although other infections, including unusual internal fungus infections, could also cause it. Today, destruction of the adrenal cortex is most commonly caused by an autoimmune disease, so we can add Addison’s disease to the long list of autoimmune diseases (diseases in which the immune system produces antibodies that attack the body’s own tissues.).
This autoimmune destruction of the adrenal cortices can occur alone or in association with other autoimmune conditions that affect the endocrine glands, such as hyperthyroidism or Type I diabetes. It is also commonly found in people or families with pernicious anemia, myasthenia gravis, vitiligo, and chronic active hepatitis, among other autoimmune diseases.
The hormones of the adrenal cortex are necessary to manage salt balance in the body and to respond to stresses of any type. Someone with Addison’s disease is therefore very susceptible to any condition that would cause him to lose salt, such as profuse sweating, or to any other condition that causes severe stress, such as a serious infection or heart attack. Lack of the hormones does not lead a person to get more infections, so frequent colds, bronchitis, etc. are not a symptom. But if a severe infection develops, lack of the hormones can prevent the body from responding adequately to it.
The destruction of the glands is usually very slow, and the development of symptoms is also so slow that it is difficult to pinpoint the beginning of the condition. The first symptom to appear is generally fatigue, which can ultimately progress to the point that a person can hardly get out of bed. Darkening of the skin, especially the crease lines on the hands, elbows, and the nipples also appear. Because of nausea and often vomiting, weight loss is almost universal. Low blood pressure is almost always present.
The diagnosis is usually easy to make if the disease is advanced, as there are typical changes on blood tests, and stimulation of the glands with adrenocorticotropin (ACTH), the pituitary hormone that regulates the adrenal hormones, fails to take place. In early cases the diagnosis may be much more difficult, particularly since fatigue, the first symptom, is so common. Addison’s disease is quite uncommon. The vast majority of people who are fatigued do not have it.
The treatment of Addison’s disease with cortisone or prednisone will reverse most of the symptoms of the condition. Occasionally, a related hormone, fludrocortisone, which has a somehat different effect on the body, must also be used. These hormones are both given as pills. Complications can arise when the person with Addison’s disease is stressed by other diseases, particularly infections, or requires surgery. The dose of cortisone must often be doubled or tripled, as the normal adrenal gland would increase under these circumstances. In very hot weather, the dose of fludrocortisone must often be increased and extra salt given. The ordinary doses of cortisone used in treatment simply replace the body’s own production of this hormone and therefore do not cause the side effects that we associate with large cortisone doses used to treat other diseases.