NPPB and Pleural effusion: Likewise, the median NT-proBNP concentration in diluted pleural effusion (Fig. 1) was significantly (p = 0.0011) different between the N-CHF and CHF cats (47 pmol/l, range: 17–329 pmol/l versus 924.5 pmol/l, range 249–1162 pmol/l).