Adrenal function in children with severe asthma treated with high-dose inhaled glucocorticoids: recommended screening tests in outpatient conditions

BACKGROUND: A number of previous studies have suggested that adrenal suppression occurs in asthmatic children treated with high-doses of inhaled glucocorticoids (IGC). This study was designed to determine the frequency of adrenal suppression in children with severe asthma treated with recommended doses of IGC: namely 500-1,000 microg/day of fluticasone propionate or the equivalent of budesonide (1,000-2,000 microg/day) for a period of at least 12 months. METHODS: Early morning cortisol (F) and ACTH serum levels were measured in 27 severe asthmatics aged 6-16 years old. The children underwent a low dose ACTH test (1 microg/1.73 m2) with a parallel glucose measurement. Twenty-four hour urine collection was performed before examination for free F (UfF) and creatinine levels. There were no clinical manifestations of adrenal hypofunction in the analyzed children. RESULTS: Of the 27 patients, 22 had normal basal and post-stimulatory levels of F and normal UfF, and the other five (18.5%) had basal serum F levels of <400 nmol/l. Four of the five also had normal post-stimulatory levels of F and normal UfF. One child had a subnormal peak F value of 484 nmol/l during the ACTH test. None of the patients had a suppressed serum ACTH level, but an elevated ACTH level was found in four children. This study provided biochemical evidence of suboptimal adrenal function in one child in the examined group (3.7%) and a good response to stimulation in all the others, even in those with slightly reduced basal cortisol levels. CONCLUSION: This study showed that the use of fluticasone in doses of up to 1,000 microg/day (or the equivalent of budesonide) as long-term treatment of children with severe asthma did not substantially affect their adrenal function.