Two to three percent of the UK population are prescribed glucocorticoid (GC) therapy and their adverse effects are associated with significant morbidity and mortality. Suppression of the hypothalamo-pituitaryadrenal (HPA) axis with the potential risk of adrenal crisis is a recognised complication of therapy. There are significant clinical challenges, not only recognition and diagnosis of the condition, but also in terms of management. There is no doubt that the prevalence of adrenal suppression is under recognised and our own data has suggested that it may be present in over 30% of patients taking prescribed GC therapy. Oral or parental GC use is most frequently associated with adrenal suppression, but it can occur across all routes of administration. In addition to the differential potency of individual GCs, we have identified a dose-dependency of effect with inhaled GCs.
The 250 μg short Synacthen stimulation test (SST) is the most commonly used dynamic assessment to diagnose adrenal suppression, but recent studies investigating the use of a random morning cortisol to determine adrenal reserve and limit the use of the SST will be discussed.
The principles of management are reliant upon GC replacement in those individuals no longer exposed to therapeutic GCs who have inadequate adrenal reserve with repeat dynamic assessments of HPA axis function to determine when the HPA-axis has recovered, accepting that the time to recovery can be highly variable. In those individuals continuing to take prescribed suppressive doses of GCs, there is a fine balance between ensuring adequate GC cover at times of inter-current illness or stress whilst not contributing to the adverse effects of exogenous GC excess.