FGF23 and hydrops fetalis: Clinical studies further indicate that circulating levels of FGF23 are also elevated in patients with dilated cardiomyopathy, ischemic heart disease, acute decompensated and chronic heart failure (HF), atrial fibrillation, and cardiogenic shock, despite normal renal function, suggesting that enhanced cardiac synthesis of FGF23 may cause elevated circulating FGF23 levels and thereby promote cardiac injury (49–61).