Certain adrenal cortex hormones control sodium retention and potassium excretion. Aldosterone is the most powerful of these hormones, but cortisone and hydrocortisone also have some effect. In primary Addison’s disease there are variable degrees of adrenal cortex destruction. This results in deficiency of both aldosterone and cortisol, thereby severely decreasing normal salt-retaining hormone influence on the kidney. Sometimes there is just enough hormone to maintain sodium balance at a low normal level. However, when placed under sufficient stress of any type, the remaining adrenal cortex cells cannot provide a normal hormone response and therefore cannot prevent a critical degree of sodium deficiency from developing. The crisis of Addison’s disease is the result of overwhelming fluid and salt loss from the kidneys and responds to adequate replacement. Serum sodium and chloride levels are low, the serum potassium level is usually high normal or elevated, and the patient is markedly dehydrated. The carbon dioxide (CO2) content may be normal or may be slightly decreased due to the mild acidosis that accompanies severe dehydration. In secondary Addison’s disease, due to pituitary insufficiency, glucocorticoid hormone production is decreased or absent but aldosterone production is maintained. However, hyponatremia sometimes develops due to an increase in AVP (ADH) production by the hypothalamus. In primary aldosteronism there is oversecretion of aldosterone, which leads to sodium retention and potassium loss. However, sodium retention is usually not sufficient to produce edema, and the serum sodium value remains within the reference range in more than 95% of cases. The serum potassium value is decreased in about 80% of cases (literature range, 34%-92%). In Cushing’s syndrome there is overproduction of hydrocortisone (cortisol), which leads to spontaneous mild hypokalemia and hypochloremic alkalosis in 10%-20% of patients (usually those with more severe degrees of cortisol excess). Use of diuretics will induce hypokalemia in other patients. The serum sodium level usually remains within reference range.