Metabolomics in the Diagnosis and Pharmacotherapy of Lung Diseases.

Metabolomics is of the increasing interests in medical research and the study of respiratory diseases. This novel type of small molecule analysis can be performed not only on conventional biological samples such as plasma or urine but also on sputum, bronchoalveolar fluid, exhaled breath condensate or exhaled breath itself (which is particularly relevant for research on respiratory diseases). On one hand, powerful analytical methodologies (including mass spectrometry and nuclear magnetic resonance spectroscopy) are labour-intensive but enable the exhaustive identification of metabolites. On the other hand, electronic noses can be used for exhaled breath analysis. Although the latter devices do not contain metabolite-specific sensors, they produce a condition- or treatment-specific "breathprint" based on pattern recognition. Breath analysis with electronic noses is noninvasive, and can be performed at the bedside in real time. Here, we review the literature on metabolomics studies in respiratory medicine, with a focus on the evaluation of responses to pharmacotherapy.