Metallic elements in exhaled breath condensate of patients with interstitial lung diseases

Epidemiological data support the hypothesis that environmental and occupational agents play an important role in the development of interstitial lung diseases such as idiopathic interstitial pneumonia (IIPs) and sarcoidosis. The aim of this study was to assess the elemental composition of exhaled breath condensate (EBC) in patients with interstitial lung diseases (ILDs) of unknown etiology and healthy subjects as an indirect evaluation of tissue burden, which could improve our understanding of the role of metals in the pathogenesis of ILDs. EBC was obtained from 33 healthy subjects, 22 patients with sarcoidosis, 15 patients with non-specific interstitial pneumonia (NSIP) and 19 with IIPs. Trace elements and toxic metals in the samples were measured by means of inductively coupled plasma-mass spectrometry. There are only small overall differences in the EBC levels of a number of metallic elements among patients with idiopathic pulmonary fibrosis (IPF), NSIP or sarcoidosis, and no pattern is capable of distinguishing them with a high degree of sensitivity and specificity. However, a pattern of pneumotoxic (Si, Ni) and essential elements (Zn, Se and Cu) with the addition of Co distinguished the patients with ILDs from healthy non-smokers with relatively high degrees of sensitivity (96.4%) and specificity (90.9%). Assessing the elemental composition of EBC in patients with different ILDs seems to provide useful information. The non-invasiveness of the EBC method makes it suitable for patients with pulmonary diseases, although further studies are required to confirm the usefulness of this approach and to better understand the underlying pathophysiological processes.