Addison's disease: clinical features and management

Addison's disease is basically an endocrine disorder in which the normal functioning of the adrenalin gland is seriously affected. This disorder affects 1 in 100,000 people and occurs equally among men and women and across different age groups. [NIDDK] Among the important functions of the adrenal gland is the secretion of Cortisol and Aldosterone, two important hormones that are essential to regulate blood pressure, cardiovascular function, inflammatory response, as well as protein and carbohydrate metabolism of the body. Aldosterone belongs to a class of hormones known as mineralocorticoids and plays a big role in maintaining the potassium sodium balance in the body. This salt balance is critical to maintain healthy blood pressure. Since the kidneys require aldosterone for sodium absorption and potassium excretion aldosterone insufficiency critically affects the kidneys ability to regulate the salt balance in the body, which in turn affects the blood pressure. Also referred to differently as Hypocortisolism or chronic adrenal insufficiency this disorder is potentially fatal if left untreated. [NIDDK]

The main cause of Addison's disease is the underfunctioning of the adrenal gland. This maybe due to the damage to the adrenal cortex by the inflammatory response of autoimmune disorders, infections, or neoplasms of the adrenal gland. Of these, adrenal gland damage by autoimmune disorders is known to be the primary cause of Addison's disease. When normal cortisol synthesis is affected directly due to the adrenal gland dysfunction the disorder is termed as primary adrenal insufficiency. However, since cortisol secretion is also dependent on the performance of another endocrine gland, the pituitary gland, pituitary anomalies will also affect the adrenalin cortisol secretion. The pituitary gland secretes ACTH (adrenocorticotropin), the hormone that triggers the adrenal to secrete cortisol. The ACTH secretion by pituitary in turn is controlled by another hormone CRH (Corticotropin releasing hormone) that is secreted by the hypothalamus in response to stress. Thus insufficient production of CRH would affect ACTH production and consequently cortisol secretion by adrenalin. Tumor or any disease of the pituitary gland may thus affect the normal adrenalin functioning. This is known as secondary adrenalin deficiency. Also, sometimes, prolonged corticosteroid therapy and some specific drugs used for the treatment of fungal infections affect natural cortisol secretion. [AAFP]

The Typical symptoms of Addison's disease include fatigue, muscle weakness, appetite loss and severe weight loss. Also, some patients may have (low blood sugar) hypoglycemia, fainting and development of dark patches on the skin (hyperpigmentation). Loss of sodium is a common problem among patients with Addison's disease and this requires the use of more salt in the diet.

Treatment of Addison's disease involves addressing the hormone deficiency using "replacement dose." [NIH] The drugs that are used as replacements for cortisol functions are known as glucocorticoids. Hydrocortisone or Dexamethasone or Prednisone is the drugs of choice. Since blood levels of Hydrocortisone can be directly measured it is an excellent choice for treatment and it makes drug dosage adjustment very easy. [Sarah Baker] Patients with Aldosterone deficiency are treated with fludrocortisone (Florinef). Inside the human body the secretion of cortisol is affected by stress. More cortisol is secreted during stress, fever, vomiting, etc. Therefore during periods of stress or physical ailments patients may require additional dosages of cortisol therapy. During sick days it is therefore necessary to consult with the physician, as a higher dose of cortisol therapy is essential. "Sick day rules" are different from normal days for glucocortisoid treatment dosage. Also, if the patient suffers from severe vomiting that would make the tablet form of cortisol therapy ineffective it is necessary to immediately administer cortisol in the form of injections. (Injectible glucocorticoid) [NIH]