Methods: We selected 27 patients who attended consecutively to our outpatient clinic complaining of one or two symptoms of asthma. They showed a normal baseline spirometry and a negative bronchodilator test. All of them underwent unspecific bronchial provocation challenges. Methacholine was performed using the tidal volumen technique and a PC20≤8 mg/ml was considered positive. Dry-powder mannitol (Osmohale TM®) was administered according to the manufacturer’s recommendations and the challenge was considered positive if a PD15≤635 mg resulted. We performed both tests with an interval of at least one week. Asthma drugs were avoided during the two weeks previous to every challenge. Skin prick tests (SPT) to the most common aeroallergens were also performed
Results: Mean age was 9 (ranged 7-15) years, 18 (66.6%) children were male. Symptoms referred were: 14 (51.8%) cough, 10 (37%) seasonal cough or shortness of breath, 5 (18.51%) cough or shortness of breath due to physical exercise and. 1 (3.7%) cough or wheezing related to respiratory infections. SPT were positive in 59.2% of the children. Eighteen (66.6%) out of 27 patients had bronchial hyperresponsiveness, and 10 (37.03%) were non atopic. All patients with a positive response to manitol showed also positivity to methacholine. Mean methacoline PC20 among responders was 0.64 ±4.08mg/ml. Manitol was performed in 16 children, and resulted positive in 8 cases (50%) with a mean PD15 of 146.8 ±246.49mg. In 2 (25%) out of 8 patients with negative manitol resulted a positive methacholine.
Conclusions: Methacholine and manitol challenge tests detected bronchial hyperresponsiveness in more than a half of the studied children with suggestive asthma symptoms. Methacoline was more sensitive than manitol.