NPPB and endothelial dysfunction: Asymmetric dimethylarginine (ADMA, ng/mL), an endogenous inhibitor of nitric oxide synthase, represents a robust marker of endothelial dysfunction, linked to arterial stiffness, N-terminal pro-brain natriuretic peptide (NT-proBNP) elevation, and CVr mortality in both dialysis and non-dialysis populations [9].