FGF23 and chronic kidney disease: Interestingly, sevelamer, but not Ca-based binders, have been shown to decrease FGF23 levels in predialysis CKD patients, but this effect could not be attributable to improved phosphate or 1,25 (OH)2D levels [21], suggesting that a relative hypocalcaemia in these subjects did not allow for FGF23 production irrespective of phosphate or 1,25 (OH)2D levels.