MEASURING THE SYSTEMIC EFFECTS OF INHALED BECLOMETHASONE - TIMED MORNING URINE COLLECTIONS COMPARED WITH 24-HOUR SPECIMENS

Background - Inhaled glucocorticoid therapy has systemic effects inclu ding hypothalamic-pituitary-adrenal (HPA) suppression. The optimal tes t for detecting these effects has not been defined. Methods - Timed ur ine collections and 09.00 hour plasma cortisol levels were obtained fr om 12 normal volunteers receiving inhaled placebo, beclomethasone (BDP ) 800 or 2000 mu g/day. The 24 hour urine samples were collected as fo llows: first hour after waking (hour 1), the next two hours after waki ng (hours 2 and 3), remainder of day, and overnight, with results expr essed as urine cortisol/creatinine (UCC) ratios and as hourly cortisol output in the timed collections. Twenty four hour urinary cortisol ex cretion was also calculated. Medication was blinded and given in rando m order with a washout period of at least 11 days between each treatme nt arm. Results - None of the UCC ratios changed with BDP 800 mu g/day . UCC ratios at hour 1, hours 2 and 3, and overnight, and 24 hour urin ary free cortisol excretion were reduced after BDP 2000 mu g/day, whil st remainder of day UCC ratio and the plasma cortisol level did not ch ange significantly. Cortisol output showed similar changes. In a follo w up study BDP 1400 mu g/day also reduced UCC ratios for the first two hours after waking. Conclusions - UCC ratios are as sensitive as the more cumbersome 24 hour urinary free cortisol excretion, and more sens itive than single morning plasma cortisol measurements, in detecting t he effects of inhaled beclomethasone on the HPA axis.