Recovery of hypothalamo-pituitary-adrenal axis suppression during treatment with inhaled corticosteroids for childhood asthma

Objective: To describe recovery of adrenal insufficiency in asthmatic children treated with inhaled corticosteroids (ICS) and cortisol replacement therapy. Design: Retrospective, observational study. Patients: A total of 113 patients, 74 male; age 10.4 (3.3-16.5) years; beclomethasone-equivalent ICS dose, 800 mu g, (100-1,000), tested by low dose short Synacthen (tetracosactide) test (LDSST), were studied. Test results were classified by basal and peak cortisol concentration: "normal" (basal > 100 nmol/L, peak > 500 nmol/L), "suboptimal" (basal > 100 nmol/L, peak 350-499 nmol/L), "abnormal" (basal < 100 nmol/L and/or peak < 350 nmol/L). Patients with suboptimal results received hydrocortisone during periods of stress only, and those with abnormal responses received daily hydrocortisone, increased during periods of stress. A total of 73 patients (68%) had >= 2 LDSSTs over 2.2 years (0.2-7.7). Measurements: Change in cortisol response to repeat LDSST (movement between diagnostic groups, difference in basal and peak cortisol > 15% [2x the inter-assay coefficient of variation]), change in BMI and height standard deviation score (SDS). Results: Baseline test results were abnormal in 17 patients (15%) and all of them had repeat tests. In 13 patients (76%), test results improved (normal in six, suboptimal in seven) and four (24%) remained abnormal. Baseline tests results were suboptimal in 54 patients (48%), of whom 50 (93%) were retested. Repeat tests were normal in 36 patients (72%), remained suboptimal in 11 (22%), and were abnormal in three (6%). Baseline tests results were normal in 42 patients, of whom six patients (14%) were retested. Results remained normal in three (50%), were suboptimal in two (33%), and abnormal in one (17%). Basal and peak cortisol levels increased by > 15% in 33/73 (45%) and 42/73 (57%) patients, respectively, and decreased by > 15% in 14/73 (19%) and 7/73 (10%), respectively. There was no significant change in height or BMI SDS. Conclusion: Recovery of adrenal function is common and occurs during continued ICS and cortisol replacement therapy.