Eisenga MF, Emans ME, van der Putten K, et al. - Researchers examined how erythropoietin-stimulating agents affect patients with both chronic heart failure and chronic kidney disease focusing on fibroblast growth factor 23 (FGF23). They conducted the EPOCARES (Erythropoietin in CardioRenal Syndrome) study randomizing 56 anemic patients (median age 74 [interquartile range 69–80] years, 66% male) with both chronic heart failure and chronic kidney disease into 3 groups, of which 2 received epoetin beta 50 IU/kg per week for 50 weeks, and the third group served as control. On providing exogenous erythropoietin, they observed a marked increase in C-terminal FGF23 levels over a period of 50 weeks, raised levels of which, even at baseline, are significantly associated with an increased risk of mortality. Results from this randomized trial thereby emphasize the strong correlation between erythropoietin and FGF23 physiology in patients with chronic heart failure and chronic kidney disease.