Usefulness of serum N-terminal-ProBNP in distinguishing ascites due to cirrhosis from ascites due to heart failure.

Background: Ascites due to cirrhosis may be difficult to distinguish from ascites due to heart failure by clinical features alone. More invasive testing is usually necessary, such as measurement of the hepatic venous pressure gradient, or paracentesis with measurement of the ascitic fluid total protein.

Aim: The aim of this study is to determine the diagnostic accuracy of serum NT-proBNP (N-terminal-pro-brain-type natriuretic peptide) in distinguishing patients with ascites from heart failure or cirrhosis.

Methods: Using a bank of previously collected fluid, we measured the serum and ascitic NT-proBNP levels in 58 patients with known cirrhosis, and 18 patients with known heart failure. Patients with both disease processes were excluded. The total protein levels in ascites was also measured and compared with serum NT-proBNP levels.

Results: The median serum NT-proBNP level was 165.7 pg/mL (range, 29.9 to 1795) in the cirrhosis group and 6100 pg/mL (range, 1110 to 116,248) in the heart failure group (P<0.001). Similar values were also found when using ascitic fluid NT-proBNP levels. Using a value of 1000 pg/mL, the sensitivity of serum NT-proBNP in ruling out cirrhosis as the cause for ascites was 100%.

Conclusions: Serum NT-proBNP seems to be an extremely powerful marker in distinguishing ascites due to cirrhosis from ascites due to heart failure. Serum NT-proBNP may potentially replace the more invasive testing presently in use.