Differentiating between feline pleural effusions of cardiac and non-cardiac origin using pleural fluid NT-proBNP concentrations.

Abstract

OBJECTIVE: To assess whether pleural fluid and urine amino terminal proB-type natriuretic peptide (NT-proBNP) can distinguish cardiac from non-cardiac causes of pleural effusion. METHODS: Blood, urine and pleural fluid were prospectively collected from cats presenting with pleural effusion categorised as cardiac or non-cardiac in origin. NT-ProBNP concentrations were measured using a feline-specific enzyme-linked immunosorbent assay. Groups were statistically compared and receiver operating characteristic curves constructed to determine cut-offs to distinguish cardiac from non-cardiac pleural effusion in plasma, pleural fluid and urine. RESULTS: Forty cats with pleural effusion (22 cardiac and 18 non-cardiac) were studied. NT-proBNP concentrations in plasma and pleural fluid were strongly correlated. Plasma (P<0&#xb7;001) and pleural fluid (P<0&#xb7;001) NT-proBNP concentrations and urinary NT-proBNT/creatinine ratios (P=0&#xb7;035) were significantly higher in the cardiac group. After receiver operating characteristic curve analysis a plasma NT-proBNP cut-off of 214&#xb7;3 pmol/mL was suggested [sensitivity=86&#xb7;4% (95% CI: 66&#xb7;7 to 95&#xb7;3%), specificity=88&#xb7;9% (95% CI: 67&#xb7;2 to 96&#xb7;9%)] and a pleural fluid NT-proBNP cut-off of 322&#xb7;3 pmol/mL was suggested [sensitivity=100% (95% CI: 85&#xb7;1 to 100%), specificity=94&#xb7;4% (95% CI: 74&#xb7;2 to 99&#xb7;0%)]. No cut-off with adequate sensitivity and specificity for urinary NT-proBNP/creatinine ratios was suggested. CLINICAL SIGNIFICANCE: Measurement of NT-proBNP in pleural fluid distinguishes cardiac from non-cardiac causes of pleural effusion in cats.