Hypothalamic-pituitary-adrenal axis suppression in asthmatic school children

Hypothalamic-pituitary-adrenal axis suppression (HPAS) when treating children with corticosteroids is thought to be rare. Our objective was to determine the prevalence of and predictive factors for various degrees of HPAS.

Clinical features of HPAS, doses, adherence, asthma score, and lung functions were recorded in 143 asthmatic children. The overnight metyrapone test was performed if morning cortisol was >83 nmol/L. Spearman correlations coefficients (r) were calculated between 3 postmetyrapone outcomes and each continuous variable. A multiple linear regression model of √postmetyrapone adrenocorticotropic hormone (ACTH) and a logistic regression model for HPAS were developed.

Hypocortisolemia was seen in 6.1% (1.8-10.5), hypothalamic-pituitary suppression (HPS) in 22.2% (14.5-29.9), adrenal suppression in 32.3% (23.7-40.9), HPAS in 16.3% (9.3-23.3), and any hypothalamic-pituitary-adrenal axis dysfunction in 65.1% (56.5-72.9). Log daily nasal steroid (NS) dose/m(2) was associated with HPAS in the logistic regression model (odds ratio = 3.7 [95% confidence interval: 1.1-13.6]). Daily inhaled corticosteroids (ICSs) + NS dose/m(2) predicted HPAS in the univariate logistic regression model (P = .038). Forced expiratory volume in 1 second/forced vital capacity <80% was associated with HPAS (odds ratio = 4.1 [95% confidence interval: 1.0-14.8]). Daily ICS + NS/m(2) dose was correlated with the postmetyrapone ACTH (r = -0.29, P < .001). BMI (P = .048) and percent adherence to ICS (P < .001) and NS (P = .002) were predictive of √postmetyrapone ACTH (R(2) = .176).

Two-thirds of children on corticosteroids may have hypothalamic-pituitary-adrenal axis dysfunction. In one-third, central function had recovered but adrenal suppression persisted. Predictive factors for HPAS are NS use, BMI, and adherence to ICS and NS.