Adrenal insufficiency associated with long-term use of inhaled steroid in asthma.

Background: We previously reported that as many as one third of hospitalized patients with asthma treated with a low to medium daily dose of inhaled steroids (ICSs) for an average of 4.5 years showed adrenal insufficiency (AI).

Objective: To re-examine this issue in consecutive outpatients with asthma because of possible subject selection bias.

Methods: One hundred twenty-one consecutive adult patients with asthma under ICS treatment for at least 6 months underwent a rapid adrenocorticotrophic hormone stimulation test. AI was defined as a morning serum cortisol level no higher than 3 μg/dL or lower than 18 μg/dL before and after administration of 250 μg of adrenocorticotrophic hormone.

Results: The mean durations of ICS use in the short-term (less than the median) and long-term (at least the median) users were 3.8 and 11.5 years, respectively. The proportion of subjects affected by AI tended to increase with the increasing cumulative dose of ICS (short-term users at a low to medium daily dose: mean cumulative dose 502 mg [15 of 34, 44.1%]; short-term users at a high dose of 941 mg [16 of 26, 61.5%]; long-term users at a low to medium dose of 1,077 mg [25 of 41, 61.0%]; long-term users at a high dose of 2,805 mg [13 of 20, 65.0%]), although not significantly. In short-term users, daily and cumulative ICS doses were significantly related to serum cortisol levels 60 minutes after taking adrenocorticotrophic hormone (r = -0.300 and -0.287, respectively; P < .05).

Conclusion: A large number of patients with asthma might have AI even with low- to medium-dose ICS treatment when ICSs are administered over a long period. Thus, it is essential that patients with asthma under ICS treatment be checked for AI much more frequently.