The importance of pleural fluid and serum NT-proBNP levels in differentiating pleural effusion due to heart failure from other causes of effusion.

Background and Objective: Pleural effusion due to congestive heart failure (CHF) typically are transudates. Light's criteria may be insufficient in determining if the pleural effusion is transudative or exudative in patients with CHF. The aim of our study was to assess the diagnostic performance of the amino-terminal fragment of pro-brain natriuretic peptide (NT-proBNP) in pleural fluid and serum for the identification of pleural effusion owing to heart failure.
Methods: The study prospectively evaluated NT-proBNP in serum and pleural fluid from patients with effusion owing to heart failure (n=51) and other causes (n=64). Measurements were made of levels of NT-proBNP by an electrochemiluminiscence immunoassay. The discriminative properties of NT-proBNP levels in identifying pleural effusion due to heart failure were determined by receiver operating characteristic curve (ROC) analysis and compared to the diagnostic value of finding a transudate by Light's criteria and serum-pleural fluid albumin gradients.
Results: Serum and pleural fluid NT-proBNP levels were significantly elevated in patients with pleural effusion owing to heart failure. The area under ROC for the diagnosis of pleural effusion from heart failure was similar for pleural fluid (0.973, 95% CI: 0.914-0.995) and serum (0.968, 95% CI: 0.890-0.989) NT-proBNP.
Conclusion: NT-proBNP levels in either pleural fluid or serum have high diagnostic values and they are easily useable parameters in the diagnosis of heart failure-related pleural effusion.