The NT-proBNP concentration in the saliva samples of the HF patients (n = 45) ranged from 18.3 pg/mL to 748.7 pg/mL with a median value of 76.8 pg/mL (interquartile range (IQR), 28.35 pg/mL to 114.7 pg/mL) (Figure 2A). Here, NPPB is linked to hydrops fetalis.