NPPB and hydrops fetalis: Since serum levels of natriuretic peptides overlap between the types of HF, and elevated values are also seen in patients with other medical conditions (e.g., renal failure, atrial fibrillation, and advanced age), natriuretic peptide levels are mainly used to rule-out HF in patients with a level below the cut-point for exclusion (N-terminal pro-B–type natriuretic peptide [NT-proBNP] < 125 pg/ml in the non-acute setting) [7–14].