The relation between adrenal function and the severity of bronchial hyperresponsiveness in children as measured by the methacholine provocation test

Background: There is no satisfactory explanation why some individuals experience severe attacks of asthma, yet others, exposed to similar stimuli, have a milder form of the disease. Objective: We tested the hypothesis that children with more severe disease may have relative adrenal insufficiency compared to the children with milder disease. Patients and Methods: Sixteen children with chronic asthma aged 8-16 years old were studied. Adrenal function was evaluated by the 24-h excretion of urinary free cortisol (UFC) before and after ACTH stimulation, and by plasma cortisol levels before and 60 min after ACTH administration. The severity of bronchial hyperresponsiveness was evaluated by the methacholine provocation test. Results: Nine children had 20% fall in forced expiratory volume in 1 sec (FEV₁) after a provocative concentration (PC₂₀FEV₁) of methacholine ≥2.5 mg/ml and were considered as having mild-moderate bronchial hyperresponsiveness (Group A). Seven children had a PC₂₀FEV₁ of ≤1.25 mg/ml and were considered as having severe bronchial hyperresponsiveness (Group B). No significant difference was found between the peak plasma cortisol response to ACTH between the two groups (634 ± 182 and 586 ± 137 nmol/l, respectively). However, there was a significant statistical difference (p <0.01) in the 24-h UFC response to ACTH between the children from Group A (345 ± 107 nmol/m²) and the children from Group B (161 ± 125 nmol/m²). Conclusions: Based on the low levels of 24-h UFC secretion in severely asthmatic children in our study, we propose the encouragement of provision of a short course of inhaled steroids to be kept at home for the emergency therapy of those children identified as having high-risk asthma.