Suspecting HPA suppression
Small studies in healthy volunteers found that short (5-7 days) courses of high dose (40-50mg) prednisolone did not produce sustained HPA suppression [18, 28]. However, adrenal suppression was observed in steroid-naïve COPD patients after taking prednisolone 40 mg daily for 14 days. This persisted in some patients for at least 21 days [29]. Treatment cessation guidelines in the British National Formulary reflect this, identifying patients who have received more than 40 mg prednisolone (or equivalent) daily for more than week or who have received glucocorticoid treatment for more than 3 weeks as requiring gradual treatment withdrawal [30].
Other patients who are likely to have HPA suppression secondary to glucocorticoid therapy include those who have been given repeat doses in the evening, have recently received repeat courses (particularly if longer than 3 weeks) and those who take a new short course of glucocorticoids within 1 year of stopping therapy [30].
The rate of treatment withdrawal in all patients is determined both by disease control and by suspicion of adrenal suppression. The rate of reduction from the initial treatment dose down to physiological doses (equivalent to prednisolone 7.5 mg) is determined by the treatment requirements of the underlying disease (e.g. table 2). The rate of reduction from physiological doses to zero is determined by the rate of HPA recovery and the need for exogenous glucocorticoid cover while endogenous glucocorticoid secretion recovers. After relatively short courses of glucocorticoids, HPA suppression can recover in days to weeks. However, where treatment duration has been long enough for adrenal atrophy to occur, recovery may take months to years or may not occur at all, necessitating long term adrenal replacement.