Addison's Disease
(= Chronic Adrenocortical Insufficiency)

When the adrenal gland function weakens the deterioration occurs usually first in the outer shell of the adrenal glands, called "cortex". Tuberculosis was a common cause of Addison's disease in the past and still is so now in development countries. However, in the US today the common cause in 70% of cases is an autoimmune process, which may be associated with industrialization.

This leads to a melting away of the cortex (called atrophy of the adrenal cortex). It occurs in about 4 per 100,000 of the US population, in all ages and equal sex distribution. It usually becomes apparent during periods of stress such as after surgery, trauma or major endocrinological stress (for instance diabetic coma etc.). However, occasionally a medication such as the antifungal ketoconazole may cause this condition. In this latter case this happens through chemical blockage of steroid synthesis (Ref. 4, p. 101).

Addison's disease symptoms:

Due to the lack of aldosterone there is a severe electrolyte disturbance with potassium being elevated in the blood and sodium being lost along with water in the urine. The end result is severe dehydration and weight loss. Blood pressures are extremely low and eventually lead to circulatory collapse. With the cortisol deficiency there is insufficient carbohydrate formation and this is a cause of hypoglycemia. The heart has decreased cardiac output, which manifests itself in weakness.

Diagnostic tests:

When blood tests, ECG's and X-rays are taken, the abnormalities are often so striking that the diagnosis is apparent or that additional tests or referrals to a specialist are done that lead to the diagnosis quickly. The serum sodium is low, there is a high potassium level and a low blood sugar level; bicarbonate levels in the blood are low and the kidney function tests show an elevated BUN value. X-ray films show often calcified adrenal glands and there may be tuberculosis in the kidneys or lungs. Hormonally, ACTH levels and renin levels are increased. The specialist likely will consider many more tests when the initial diagnosis of chronic adrenocortical insufficiency has been established.

This is important, because it has to be established whether or not the insufficiency of the adrenal glands is due to a primary process within the adrenal glands or whether the adrenal glands are merely secondarily affected as a result of a pituitary gland tumor that led to a deficiency of ACTH stimulation. In the case of tuberculosis or an autoimmune process leading to direct atrophy or destruction of the adrenal gland tissue the corticosteroid deficiency is the cause of the primary Addison's disease (see table). Further testing including CT or MRI scans of pituitary gland and/or adrenal glands can help in distinguishing between these diagnostic possibilities. Further hormone stimulation or suppression tests through the endocrinologist are also useful with this distinction. The reason this distinction is important to make comes from the fact that treatment for these two conditions is significantly different.

Acute adrenal insufficiency must be treated promptly to avoid an adrenal crisis. Hydrocortisone is initially given intravenously by the treating physician along with electrolyte solutions to correct the fluid/electrolyte imbalance. Any infection that might also be present has to be adequately treated as well. Needless to say that this is also true for tuberculosis.

After the initial acute therapy the patient is switched to a maintenance therapy. This consists of hydrocortisone in the morning (usually 20mg) orally and about 10 or 20 mg of hydrocortisone in the afternoon replacing the glucocorticosteroids. Fludrocortisone in the dosage of 0.1 or 0.2mg is given once per day, which replaces the mineralocorticoid aldosterone hormone.

Secondary Addison's disease may require a neurosurgical referral for pituitary gland surgery through one of the sinus cavities is often required (" transsphenoidal hypophysectomy "). In this case there might be other hormone deficiencies such as hypothyroidism, which would also require thyroid hormone replacement.

Disclaimer:

This outline is only a teaching aid to patients and should stimulate you to ask the right questions when seeing your doctor. However, the responsibility of treatment stays in the hands of your doctor and you.

References:

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Last Modified: Oct. 29, 2006