Adrenal responses to low dose synthetic ACTH (Synacthen) in children receiving high dose inhaled fluticasone

Background and Aims: Clinical adrenal insufficiency has been reported with doses of inhaled fluticasone proprionate (FP) >400 μg/day, the maximum dose licensed for use in children with asthma. Following two cases of serious adrenal insufficiency (one fatal) attributed to FP, adrenal function was evaluated in children receiving FP outwith me licensed dose. Methods: Children recorded as prescribed FP ≥500 μg/day were invited to attend for assessment. Adrenal function was measured using the low dose Synacthen test (500 ng/1.73 m2 intravenously) and was categorised as: biochemically normal (peak cortisol response >500 nmol/l); impaired (peak cortisol < 500 nmol/l); or flat (peak cortisol <500 nmol/l with increment of <200 nmol/l and basal morning cortisol