Addison's Disease
Primary adrenal insufficiency: the cortex fails, so cortisol and usually aldosterone are lost together, and any physiological stress can tip a stable patient into adrenal crisis.
Definition
Addison's disease is primary adrenal insufficiency: disease of the adrenal cortex itself, reducing cortisol and usually aldosterone. Autoimmune destruction is the commonest cause in adults and congenital adrenal hyperplasia the commonest in children. It is lifelong, and treatment is replacement plus crisis prevention.
First principles
Primary disease loses cortisol and aldosterone together
Addison's disease destroys the adrenal cortex, so both cortisol and aldosterone fall. Secondary and tertiary insufficiency start above the gland, in the pituitary or hypothalamus, and aldosterone is preserved because renin and angiotensin, not adrenocorticotropic hormone (ACTH), drive it. Aldosterone loss is therefore the discriminator: salt wasting, volume depletion, postural hypotension, hyponatraemia and hyperkalaemia all point to primary disease. It is also why only primary disease is given a mineralocorticoid.
This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.