NPPB and chronic kidney disease: In this study, three patients with CKD had an estimated glomerular filtration rate (GFR) of more than 60 mL/min per 1.73m2, and their NT-proBNP levels were significantly above 900 pg/mL (NT-proBNP and GFR cut-off values reported by Anwaruddin et al. (10) for patients with underlying CKD.