A diagnosis of adrenal insufficiency should be suspected in the presence of a number of non-specific symptoms (fatigue, anorexia, weight loss, hypotension, hyponatremia and hyperkalemia amongst adrenal causes of insufficiency). The diagnosis should be considered in case of pituitary disease or a state of shock. Treatment should be commenced immediately without waiting for confirmation from biochemical tests, which rely on cortisol level at 8am (expected to be low) and on ACTH level (expected to be high in the case of primary adrenal insufficiency). If these tests are inconclusive, a Synacthen test should be carried out. The threshold limits are provided as a guide. Low plasma cortisol and normal to low plasma ACTH indicates a pituitary origin for the deficiency. In this situation, the Synacthen test can give a false normal result, and if this adrenal insufficiency is strongly suspected, an insulin hypoglycemia test or metyrapone (Metopirone®) test should be carried out. In children younger than 2yr, hypoglycemia, dehydration and convulsions are frequently observed and in young girls, virilization is suspect of congenital adrenal hyperplasia . The circadian rhythm of cortisol is not present until after 4months of age and the Synacthen test is the only one that is feasible. In children older than 2yrs, the signs and diagnostic methods are the same as in the adult. Cessation of corticosteroid treatment is a frequent circumstance however there is little published data and no evidence for definitive guidelines. After ceasing a short period of corticosteroid treatment, patient education is all that is required. After longer treatment, consensus leaves the choice up to the physician, between educating the patient and prescribing hydrocortisone in case of stress, or prescribing low daily dose hydrocortisone and evaluating the ACTH axis over time until normal function is recovered.