In Addison’s disease (also called primary adrenal insufficiency), j there is deficiency of three adrenal hormones-Cortisol, aldosterone, and DHEA. (i) Deficiency of Cortisol results in hypoglycemia due to increased peripheral glucose utilization associated with increased sensitivity to insulin, with impaired gluconeogenesis, hepatic glucose production, and glycogen synthesis. Cortisol deficiency also causes a feedback increase in ACTH secretion.
The high levels of ACTH cause hyperpig- mentation of skin, (ii) Deficiency of aldosterone causes anorexia, i weakness, weight loss, vomiting, hyper-pigmentation, hyponatremia (natriuresis), hyperkalemia, hypotension, metabolic acidosis, increased plasma ADH, hypoosmotic dehydration, and elevated plasma ACTH. (iii) Deficiency of androgens leads to the loss of pubic hair, reduced muscle mass,; and loss of libido in men and women.
Amenorrhea may also occur.Secondary adrenal insufficiency occurs when there is inadequate stimulation of the adrenals by ACTH. It results in the deficiency of two adrenal hormones – Cortisol and DHEA. The secretion of aldosterone remains nearly unaffected.
The clinical features are similar to those of primary insufficiency. However, there is absence of hyperpigmentation (since there is no hypersecretion of ACTH). Also, since there is no aldosterone deficiency, fluid and electrolyte disturbances do not occur, and the hypotension that occurs occasionally is attributable to Cortisol deficiency.