The results of DeLong’s test suggested that there was no significant difference between FGF21 and NT-proBNP in distinguishing between patients with advanced HF and those with mild HF (p = 0.7052, 95% CI for difference in AUC: −0.18 to 0.12), but FGF21 had moderate sensitivity and specificity while NT-proBNP had high specificity but low sensitivity. Here, FGF21 is linked to hydrops fetalis.