Background: We reported in ERS Annual Congress 2007 that hypothalamic-pituitary-adrenal (HPA) axis was diagnosed to be suppressed by a low dose (1.0 mcg) adrenocorticotropin (ACTH) test in 25 percent of 56 adult asthmatics regularly treated with inhaled corticosteroids (ICS).
Aim: To determine whether the suppressed HPA axis diagnosed by a low-dose ACTH test is associated with reduced bone mineral density (BMD) in adult asthmatics treated with ICS.
Methods: Fifty-six asthmatic patients (M/F: 17/39) were subjected to an i.v. injection of 1.0 mcg ACTH at am 9.00. Three samples (0, 30 and 60 min.) were examined for serum cortisol (F) level. Both the basal F level of more than 303nmol/L and the peak F level of more than 500nmol/L indicated normal response. BMD was measured at the lumbar spine and the femoral bone by dual-energy X-ray absorptiometry in all patients.
Results: Twenty-five percent (M/F: 5/9) patients were diagnosed to be suppressed HPA axis. BMD (Z score) at the neck and total femoral bone was significantly lower in these 9 female patients than that in 30 female patients showing normal response of F. There was no statistical significance for age, BMI, menstrual status, duration of asthma, daily dose of ICS, cumulative dose of ICS for one year and a type of ICS. Conclusion: A low-dose ACTH test revealed that one-fourth patients treated with ICS were in suppressed HPA state. Female patients diagnosed suppressed HPA axis showed reduced BMD. Suppressed HPA axis diagnosed by a low-dose ACTH test could indicate disfavoring effects of ICS on bone in female asthmatic patients.