Utilization of B-type natriuretic peptide and NT-proBNP in the diagnosis of pleural effusions due to heart failure

PURPOSE OF REVIEW: The natriuretic peptides B-type natriuretic peptide (BNP) and NT-proBNP have been incorporated into the existing clinical guidelines for the diagnostic evaluation of heart failure. Recent evidence has provided important information regarding the relative value of each of these peptides to differentiate between pleural effusions caused by heart failure and those attributable to other causes. RECENT FINDINGS: In a meta-analysis of 10 studies, which included 1120 patients, pleural fluid levels of NT-proBNP had a pooled sensitivity and specificity of 94%, a positive likelihood ratio of 15.2, and a negative likelihood ratio of 0.06 in identifying heart failure-related effusions. Because pleural fluid and serum natriuretic peptide levels are closely correlated and display similar discriminatory properties, blood tests alone are sufficient. More than 85% of heart failure patients whose pleural fluids meet exudative criteria exhibit high pleural NT-proBNP concentrations. The diagnostic performance of pleural fluid BNP has been reported to be inferior to that of NT-proBNP. SUMMARY: NT-proBNP is an established biomarker of heart failure-associated effusions and the most effective tool for recognizing cardiac effusions that are misclassified as exudates by Light's criteria. If clinicians choose pleural fluid specimens for natriuretic peptide testing, the lower diagnostic accuracy of BNP makes it a poor substitute for NT-proBNP measurements.