Clinical perspective: biomarkers in pulmonary arterial hypertension.

Biomarkers are objectively measured characteristics used as indicators of disease in clinical practice and as surrogate endpoints in clinical trials. The six-minute walk test has been widely used as a trial endpoint in pulmonary arterial hypertension (PAH) to gain approval for targeted therapies. Other biomarkers have been studied to overcome certain limitations of the walk test. Potential clinical applications for biomarkers in PAH include screening, determination of prognosis, and monitoring response to therapy. Measurement of the B-type natriuretic peptides is currently recommended by guidelines, despite a lack of appropriate validation in the PAH population. Novel biomarkers based on recently discovered pathobiologic pathways have been identified, like CXC chemokine ligand 10, C-reactive protein, high-density lipoprotein cholesterol and growth-differentiation factor-15. Rigorous statistical, biologic and clinical validation should be necessary before any biomarker can be endorsed for widespread clinical use.