? Adrenal failure
Patients with adrenal failure may present acutely with hypoglycaemia or hyponatraemia and dehydration or chronically with general malaise, anorexia, vomiting, intermittent abdominal pain and weight loss. Signs of dehydration include hypotension, often postural, and tachycardia. Pigmentation is seen on sun exposed areas and also sites of friction such as the palmar creases and buccal mucosa.
If the diagnosis is strongly suspected, there should be no delay in administering glucocorticoids as soon as blood has been taken for plasma cortisol and ACTH; the definitive diagnosis can wait. If dexamethasone is given, the short Synacthen test can be performed the next day as dexamethasone does not interfere with cortisol assays.
Care should be taken in interpreting the short Synacthen test in women taking the oral contraceptive since elevations in cortisol-binding globulin will result in high basal and stimulated cortisol concentrations (Clark et al 1998, Ostlere et al 1998).
Patients given with long term corticosteroid therapy will have become hypoadrenal due to adrenal atrophy. As a result they may have a poor response to exogenous ACTH, but there is no evidence that the response to ACTH is useful in tailoring glucocorticoid withdrawal. If they appear to have inappropriate symptoms and concern persists about their adrenal reserve, it is probably better to evaluate the entire hypothalamo-adrenal axis eg im glucagon test.
- Clarke PMS, Neylon I, Raggatt PR, Sheppard MC, Stewart PM. Defining the normal cortisol response to the short Synacthen test: implications for the investigation of hypothalamo-pituitary disorders. Clin Endocrinol (Oxf) 1998;49:287-292.
- Ostlere LS, Rumsby G, Holownia P, Jacobs HS, Rustin HA, Honour JW. Carrier status for steroid 21-hydroxylase deficiency is only one factor in the variable phenotype of acne. Clin Endocrinol (Oxf) 1998;48:209-215.