Addison's Disease- Causes,symptoms and Treatment

The human body contains two adrenal glands which are situated above the kidney and comprise two compartments, the inner medulla and the outer cortex. The glands weigh 4g and measure roughly 2-3cm wide and 4-6cm long. The adrenal gland is one of the principal endocrine glands and the triple-zoned adrenal cortex is responsible for the production of many hormones including glucocorticoids such as cortisol, and mineralocorticoids such as aldosterone, which regulate sodium, potassium and hydrogen ion balance as well as blood pressure.

Addison's disease is caused by the bilateral destruction of all zones of the adrenal cortex leading to aldosterone and glucocorticoid deficiency. Almost all the entire gland has to be destroyed before symptoms become apparent. The destruction is mainly the result of autoimmune adrenalitis, but can also be caused by the infection tuberculosis which is the predisposing cause in around a fifth of sufferers. Other causes include secondary tumour deposits, infiltrative lesions, congenital adrenal hyperplasia/hypoplasia,amyloidosis, haemochromatosis and surgical removal of the glands. The disease is very rare and affects around 1 in 100 000 people.

The disorder is characterised by symptoms including lethargy, weakness, skin pigmentation, anorexia, abdominal pain, weight loss, and salt cravings. Symptoms appear slowly and the disease may go unnoticed for a long period of time. During primary adrenal failure which occurs in Addison's patients if they suffer trauma or forget to take their HRT, patients will experience nausea, vomiting, hypotension which gets worse when standing, depression, dizziness and hypoglycaemia. If adrenal failure is left untreated it can be fatal.

The disorder is diagnosed on finding the following biochemical features; low cortisol, low aldosterone, hyponatraemia, low carbon dioxide, hyperkalaemia, and high renin levels. An ACTH stimulation test can also be carried out in order to see if the patient's adrenal glands produce cortisol in response to ACTH, if they do not this is another good marker of Addison's disease. The presence of 21-hydroxylase autoantibodies suggest the cause of the disorder to be autoimmune adrenalitis.

Treatment involves replacing the hormones that the damaged adrenal gland can no longer produce. The hormones must be taken every day. Cortisol is given in the form of hydrocortisone tablets and aldosterone is given as fludrocortisone acetate. Patients are also advised to carry a medical card with their condition clearly highlighted, so that in cases of adrenal failure treatment can be initiated as quickly as possible.