LCN2 and chronic obstructive pulmonary disease: Of interest, other proteins can be used to detect lung function impairment, such as Fibrinogen, Neutrophil gelatinase associated lipocalin, Extracellular newly identified RAGE-binding protein and Heparin-binding EGF-like growth factor, showing significantly different serum levels when comparing mild/moderate and severe/very severe COPD patients to smoking and non-smoking controls [34].