Addison's disease

Addison's disease or primary adrenocortical failure is a rare condition, most commonly caused in the UK by autoimmune destruction of the adrenal glands. The insidious onset of symptoms over many months means there is often a delay in diagnosis and patients can first present in adrenal crisis. The diagnosis is made by measurement of a low serum cortisol at 9 a.m. in the presence of an elevated adrenocorticotrophic hormone (ACTH) or by a poor cortisol response to exogenous ACTH on provocation testing. There are many possible causes of adrenal failure and once the diagnosis of adrenal insufficiency has been made these should be differentiated further. Replacement with hydrocortisone and fludrocortisone should approximate physiological levels as closely as possible and be monitored closely. Additional adrenal androgen replacement can be added, particularly if the patient has a poor quality of life, although the long-term effects of this are unknown.