Biomarkers in lower respiratory tract infections.

This review aims to provide physicians with an overview of the potential of biomarkers to complement existing clinical severity scores and in conjunction with clinical parameters to improve the diagnosis, risk-stratification and management of lower respiratory tract infections (LRTIs). The usefulness of biomarkers for diagnosing LRTIs is still unclear. However, the specificity of pneumonia diagnosis is high when high sensitivity C-reactive protein (CRP) and procalcitonin (PCT) are used. PCT, CRP and particularly pro-atrial natriuretic peptide (MR-proANP), pro-vasopressin (CT-proAVP) and proadrenomedullin (proADM) levels can reliably predict LRTIs mortality. These markers do not significantly improve the severity scores predictive values, confirming that biomarkers are meant to complement, rather than supersede, clinician's judgment and validated severity scores. Biomarkers, and particularly PCT, are useful tools as antibiotic treatment duration indicators both in pneumonia and exacerbations of chronic obstructive pulmonary disease (COPD). Even if more data are required to fully appreciate the role of biomarkers in LRTIs management, there is emerging evidence that biomarkers have the potential to improve the daily clinical management of LRTIs.