G474(P) Role of low dose short synacthen test (LDSST) in the assessment of adrenal reserve in children with chronic Asthma

Abstract

BackgroundThe role of inhaled corticosteroids (ICS) is undisputable in the management of chronic asthma. However, the regular or recurrent use of ICS results in suppression of hypothalamic-pituitary–adrenal (HPA) axis, that could be asymptomatic or results in adrenal crisis. The Low Dose Short Synacthen Test (LDSST) has been shown to be a sensitive test of adrenal function during ICS therapy.AimsTo describe recovery of adrenal function in children with abnormal cortisol responses to the LDSST during treatment with ICS for asthma.MethodologyThe result of LDSST’s performed in children treated with ICS for asthma between 2011–2014 was studied. Results of previous and subsequent LDSST were also collected. Age, gender, cumulative corticosteroid dosage and the outcome of LDSST were analysed. Patients were classified as having normal (>500nmol/L), suboptimal (350–499nmol/L) and abnormal (<350nmol/L) cortisol responses from the results of their first LDSST. Baseline cortisol levels <100nmol/L at 9am were considered abnormal. The repeat LDSST test results were also analysed to assess the movement of patients between the groups and time period for that shift.ResultsData are shown as median (range) 184 LDSSTs were carried out in 81 patients (51M), age 10.6 years (0.7–17.1). Duration of follow up was 1.6 years (0–6.3), and the number of LDSST’s was 2.3/patient (1–6). Recovery of adrenal function was observed in 65% and 50% of patients with suboptimal and abnormal group respectively. Test results worsened in 25% of patients including patients in normal group. 13/52 patients with impaired, and 4/14 patients with abnormal tests were not tested further. 10 patients (12%) had basal cortisol levels <100nmol/l, of which 4 became normal and 6 still remained abnormal after 1.9 years (0–6.3) of follow-up. The total daily dose of inhaled corticosteroid (Beclomethasone equivalent) in suboptimal and abnormal group was 780 mcg/day, which was 35% higher than the patients in normal group (p = 0.01).Conclusions1) Adrenal suppression is common in chronic asthma patients receiving ICS 2) Adrenal function could worsen in patients who were tested normal previously and hence high index of suspicion is required to diagnose this early. 3) Higher dose of inhaled corticosteroid dose is likely to result in suboptimal or abnormal LDSST.