Biomarker research in COPD is becoming the most rapidly progressing sphere in respiratory medicine. Although "omics" generate a huge amount of biomarkers, fibrinogen is the only one validated by the European Medicines Agency. Thousands of studies analyzing different biological samples from the respiratory tract, collected in different ways, using various kits and techniques are generating more and more data, rendering biomarkers very confusing rather than having practical value. It seems that in order to be applicable and validated, biomarkers should be analysed in an accurately described cohort of patients, homogeneous in disease severity and activity. As COPD has multiple mechanisms of pathobiology it raises the issue of which is the most appropriate biological sample reflecting each of them. Unified criteria for tissue sampling, validated kits for respiratory tract probes and standardized technologies should be announced. The review presents the biomarkers that are currently validated and raises the problem of standardization.
Keywords: COPD; biomarkers; standardization; validation.