Methacholine inhalation challenge in children with idiopathic chest pain.

Bronchial reactivity to inhaled methacholine (MCH) was evaluated in 32 patients with 'idiopathic' chest pain. Each pain was recurrent in nature. The incidence of cases with a provocative concentration causing a 20% fall in the forced expiratory volume in 1 sec (PC20) of 10 mg/ml or less was 62.5% (20 cases), while it was only 11.1% (three cases) in 27 healthy controls. Seventeen patients had no personal history of allergic diseases, elevated serum IgE level or positive house dust mite-specific IgE antibody. Among these 17, eight (47.1%) had a PC20 of 10 mg/ml or less, the incidence of which was also higher than that of the healthy controls. During the challenge, eight patients complained of chest pain similar to that experienced before. The present results indicate that bronchial hyper-reactivity is an important cause of 'idiopathic' chest pain. Patients with unexplained chest pain should be considered for inhalation challenge.