Hypothalamic-pituitary-adrenal axis suppression in asthmatic children on inhaled and nasal corticosteroids: is the early-morning serum adrenocorticotropic hormone (ACTH) a useful screening test?

To cite this article: Zollner EW, Lombard C, Galal U, Hough S, Irusen E, Weinberg E. Hypothalamic–pituitary–adrenal axis suppression in asthmatic children on inhaled and nasal corticosteroids: is the early-morning serum adrenocorticotropic hormone (ACTH) a useful screening test? Pediatr Allergy Immunol 2011; 22: 614–620. Abstract Background: Hypothalamic–pituitary–adrenal axis suppression (HPAS) in asthmatic children treated with inhaled corticosteroids (ICS), with or without nasal steroids (NS), may be more common than previously thought. Only dynamic testing will identify children at risk of adrenal crisis. It is impractical to test all asthmatic children for HPAS with a gold standard adrenal function test, i.e. the metyrapone or insulin tolerance test. Objective: To determine which clinical or biochemical parameter is the most useful screening test for HPAS in asthmatic children. Methods: Twenty-six asthmatic children, 5–18 yr old, on ICS ± NS, not treated with oral or topical steroids in the preceding year were recruited. Height, weight, height velocity, weight velocity and a change in systolic blood pressure from the recumbent to the standing position (ΔSBP) were recorded. Early-morning urine for urinary free cortisol (UFC) and urinary cortisol metabolites (UCM) was collected. UFC was analysed by both a chemiluminescent assay and gas chromatography/mass spectrometry (GC-MS). Morning serum cortisol and adrenocorticotropic hormone (ACTH) levels were measured. The overnight metyrapone test was performed if the fasting morning serum cortisol was >83 nmol/l. HPAS was diagnosed if the ACTH failed to rise >100 pg/ml after metyrapone. Spearman correlation coefficients (r) were calculated between the post-metyrapone ACTH and each variable. A receiver-operating characteristics (ROC) curve was drawn for the most promising test, and the diagnostic performance was calculated. Results: All clinical and biochemical parameters investigated were weakly and non-significantly correlated with the post-metyrapone ACTH, except for the morning serum ACTH (r = 0.68; p