FGF23 and chronic kidney disease: We found a tight positive association between circulating intact FGF23 and serum aldosterone in human, canine, and feline CKD patients, as well as in experimental murine CKD (humans: rS = 0.57, p = 0.0368; dogs: rS = 0.66, p = 0.0019; cats: rS = 0.75, p = 0.0003; mice: rS = 0.49, p = 0.0004).