Document resource
Indirect airway hyperresponsiveness (AHR) is a key physiologic feature of asthma, reflecting characteristic structural and functional changes in airway lumen and walls. Mannitol bronchial challenge testing provides a standardized, safe, efficient method for assessing indirect AHR. In November 2024, St. Vincent’s Private Hospital (SVPH) introduced a mannitol challenge service to support asthma diagnosis, guide therapeutic decisions, and an objective evaluation of emerging asthma treatments.We conducted a retrospective review of all mannitol challenge tests performed in our Department between November 2024 and December 2025. Referral data, test outcomes, and seasonal testing patterns were analyzed.A total of 54 patients were referred; of these, 47 tested negative for AHR (22 males and 25 females). A positive response to mannitol was defined as a decrease in forced expiratory volume in the first second (FEV1) of 15% compared to baseline values or if FEV1 decreased more than 10% between consecutive doses. 7(13%) tested positive (4 males, 3 females). The average male age was 49yrs (average fall in FEV1 was 19%). Average female was 51yrs (average fall in FEV1 was 18%). Positive results show an even distribution across both genders. Review of eosinophil count for subjects with a positive mannitol test showed two patients with a high count (1 Female 0.6 and 1 Male 0.7, Normal range (0.0-0.5 10^g/l). Test distribution across the year showed notable clustering, with 12 tests performed in November–January, 8 in February– April, 11 in May–July, and 23 in August–October.The first year of mannitol challenge implementation at SVPH demonstrates successful integration of this indirect AHR assessment into clinical pathways for asthma evaluation. Positive tests were identified in both sexes with similar physiologic responses. The majority tested negative, suggesting absence of significant airway hyperresponsiveness in most cases. The high volume during late summer and early autumn may reflect seasonal variation in asthma symptom burden or referral patterns. These findings support continued use and expansion of mannitol challenge testing as a valuable diagnostic and monitoring tool within asthma care at SVPH. Further analysis, including correlation with clinical history and treatment outcomes, would be valuable to strengthen the interpretation of these findings.