Introduction Inhaled corticosteroids (ICS) are the mainstay of treatment in asthma. Whilst they are felt to be safe in low doses, a number of case studies have demonstrated adrenal suppression in higher doses, particularly in paediatric patients. The relative frequency of this is largely unknown, but we believe it may be significantly under-recognised in patients with difficult to treat asthma. As part of our difficult asthma protocol we measure random cortisol levels and proceeded to further investigations if this was abnormal or the patient presented with symptoms of adrenal insufficiency.
Methods Patients were assessed through the Difficult Asthma Service in Leeds which is a tertiary referral centre for West Yorkshire. Patients who had non-specific symptoms out of keeping with asthma, either had a random serum cortisol taken or had a short synacthen test. Patients were classified as: adrenal insufficient with a cortisol less than 50nmol/L or a positive short synacthen test, and adrenal sufficient with a random cortisol greater than 120nmol/L or a negative short synacthen test. A further group was defined as suboptimal if their random cortisol was between 50–120nmol/L Data were also collected on ICS dose and type, and atopic status.
Results Ninety-two random cortisol samples have been taken to date. Of these, 8 patients who were not on oral corticosteroids were found to have adrenal insufficiency (8.7%). Seven patients had a random cortisol less than 50nmol/L and one had a positive short synacthen test. Of the patients with adrenal insufficiency six patients were on a combination inhaler including fluticasone, and all received a daily BDP dose over 1000mcg. None of the patients with adrenal insufficiency demonstrated evidence of atopy, except one patient with co-existent ABPA receiving itraconazole therapy.
Conclusions We have identified a significant number of patients with evidence of adrenal insufficiency, with the majority identified by a random cortisol. This is likely to be under-estimated, as the 92 samples include patients on maintenance oral corticosteroids. In patients with difficult asthma, multiple or atypical symptoms, there should be a low threshold to investigate for adrenal insufficiency particularly those receiving high dose ICS.