Use of the Low-Dose Corticotropin Stimulation Test for the Monitoring of Children with Asthma Treated with Inhaled Corticosteroids

Objective: Subnormal hypothalamic-pituitary-adrenal (HPA) function and rare cases of adrenal crisis have been reported in asthmatic children treated with inhaled corticosteroids. We investigated subnormal HPA activity and followed up affected patients until recovery of normal HPA functions. Study Design: 100 children with persistent asthma underwent low-dose corticotropin testing, with the administration of 1 µg of 1–24 ACTH intravenously. Treatments were beclomethasone dipropionate as a metered-dose inhaler, n = 14, budesonide as a dry-powder inhaler, n = 16, fluticasone propionate as a metered-dose inhaler n = 31 or a dry-powder inhaler n = 39. The mean commercially labelled dose was 520 ± 29 µg/day (mean ± SEM, range: 160–1,000) and the equipotent dose (which compares the efficiency of these drugs for treating asthma and their responsibility for systemic effects) was 890 ± 55 µg/day (range: 200–2,000). Results: The mean stimulated cortisol level ± SEM (and range) of the patient was 482 ± 12 (148–801), and that of 40 age-matched controls was 580 ± 12.5 (439–726), (SD = 79). The result was subnormal (more than 2 SD below the mean of the controls) in28 of the 100 patients. One–four stepwise decreases of 10–100% in the daily equipotent doses received by the patients with abnormal low-dose corticotropin testing results led to normal results in subsequent low-dose corticotropin testing in 27 retested patients. The mean time interval between two tests was 5 months (range: 2–6 months) and the mean period required for normalization of the test was 13 months (range: 2–21). Only one case of asthma exacerbation and no adrenal crisis were observed over these periods. Conclusions: Decreasing daily equipotent doses led to recovery of normal HPA function without asthma exacerbation. Thus, a revision of the doses of inhaled corticosteroids used in asthmatic children with a progressive decrease to the consensus-recommended doses should decrease the systemic effects of inhaled corticosteroids, while minimizing the risk of asthma exacerbation.