For example, in the BIOlogy Study to TAilored Treatment in Chronic HF (BIOSTAT-CHF) study, the elevation of FGF23 identified a subset of HF patients with more severe disease and is associated to impaired up-titration of angiotensin-converting enzyme inhibitors (ACEi) and angiotensin receptor blockers (ARBs) [10]. Here, FGF23 is linked to hydrops fetalis.