Introduction: Chronic kidney disease (CKD) and congestive heart failure (CHF) patients have higher serum B-type natriuretic peptide (BNP), which alters the test interpretation. We aim to define BNP cutoff levels to diagnose acute decompensated heart failure (ADHF) in CKD according to CHF subtype: heart failure with preserved ejection fraction (HFpEF) and heart failure with reduced ejection fraction (HFrEF). Material and methods: We reviewed 1,437 charts of consecutive patients who were admitted for dyspnea. We excluded patients with normal kidney function, without measured BNP, echocardiography, or history of CHF. BNP cutoff values to diagnose ADHF for CKD stages according to CHF subtype were obtained for the highest pair of sensitivity (Sn) and specificity (Sp). We calculated positive and negative likelihood ratios (LR+ and LR–, respectively), and diagnostic odds ratios (DOR), as well...