Addison's disease (primary adrenal insufficiency) is a result of destruction of the adrenal cortex resulting in reduced production of glucocorticoids (such as cortisol), mineralocorticoids (such as aldosterone) and adrenal androgens (such as dehydroepiandrosterone). The absence of cortisol leads to increased production of adrenocorticotropic hormone (ACTH) because negative feedback to the pituitary gland is reduced.
Diagnosis of Addison's disease is often delayed because symptoms are non-specific, common, and overlap with many other conditions.
A person with Addison's disease may present with a sudden crisis precipitated by intercurrent infection or stress. The adrenal glands cannot supply the extra corticosteroids needed to cope with the stress, and life-threatening symptoms develop. Features include hypotension, hypoglycaemia, acute abdominal pain, low-grade fever, and vomiting. Even if the person is young and otherwise fit, adrenal crisis may result in severe dehydration, hypovolaemic shock, altered consciousness, seizures, stroke, or cardiac arrest.
<100 nmol/L: Highly likely adrenal insufficiency
100-500 nmol/L: Refer for Synacthen test
Hyponatraemia: 90% of cases
Hyperkalaemia: 65% of cases
ACTH stimulation test
Normal response: increased cortisol