Addison Disease: Adrenal Insufficiency
Named for Thomas Addison, the physician who first described the condition in 1855, Addison disease is adrenocortical insufficiency, due to dysfunction or destruction of the adrenal cortex. Since this can occur gradually with symptoms developing only after about 90 percent of both adrenal glands is destroyed, Addison disease tends to present between the ages of 30-50 years. It is a very rare disease, with an incidence today of 40-60 cases per 1 million people. It was more common in the past as a sequela of tuberculosis (TB) which can destroy the adrenal glands, and several famous individuals have had it, most notably US President John F Kennedy. Certain authors such as Charles Dickens and Jane Austen have been speculated to have had Addison disease as well, and one writer has noted Osama bin-Laden exhibiting symptoms.
When not the result of TB, Addison disease is thought to develop due to atrophy, lymphocytic infiltration, and fibrosis of the adrenal cortex, resulting from autoantibodies, generally with no destruction of the adrenal medulla, and patients may be predisposed due to hereditary factors. Although usually the problem in Addison disease lies in the adrenal cortex, the condition also can result if there is a lesion in the pituitary gland that interrupts the secretion of ACTH. In such cases, both cortisol and ACTH will be low.
Due to a lack of cortisol, patients may exhibit nausea, vomiting, and fatigue as in the case of this patient. Females may present with amenorrhea and men with impotence and decreased libido. Patients are hypotensive and may demonstrate orthostatic intolerance and complain of dizziness as well. If severe this can lead to presyncope and syncope. Hypoglycemia is to be expected due to lack of cortisol. In diabetic patients, patients also may become hypoglycemic due to increased sensitivity to insulin.
Often, public and axillary hair is absent or very sparse. Reduced cortisol leads to an increase in pituitary secretion of ACTH, which stimulates melanocytes in the skin to produce melanin; thus, patient's may describe increases in "tanning" or "freckles". Generally, this effect precedes the other symptoms, since for a time the increased ACTH can help to squeeze a little more cortisol out of the deteriorating adrenal glands. Eventually, however, weakness, fatigue, reduced appetite, and weight loss develop progressively.
Hyperkalemia (high serum potassium) results from the lack of cortical hormones and this leads to myalgias and flaccid muscle paralysis. Hypercalcemia (high serum calcium) may be present in some cases, but since hypoparathyroidism also can be present, hypocalcemia also may occur.