Adrenal insufficiency (Case study 2, box 2)
Patients taking long term systemic glucocorticoids are at risk of HPA suppression. Where this has occurred, abrupt withdrawal of exogenous glucocorticoids or physiological stress such as intercurrent illness or surgery can cause life-threatening acute adrenal insufficiency. Although not all patients taking long term glucocorticoids develop adrenal insufficiency [22], it can be extremely difficult to distinguish those who do from those who don’t. Potency, dose and duration of glucocorticoid treatment are imperfect predictors, patients may be asymptomatic even when therapy is withdrawn and blanket HPA testing is considered impractical. A general clinical approach therefore is to have a low threshold for suspecting HPA suppression in patients taking glucocorticoids and to require a gradual withdrawal of treatment for all those considered to have reached that threshold. Where treatment withdrawal is hampered by the emergence of symptoms (e.g. Case study 2, box 2), testing for HPA suppression can be useful to determine whether these are manifestations of adrenal insufficiency.