Changes to bone biomarkers after IV ferric carboxymaltose. Changes in (A) serum iFGF23, (B) cFGF23, (C) fractional excretion of phosphate and (D) serum phosphate after IV ferric carboxymaltose. Error bars denote standard error of the mean. aP < 0.0001 versus Day 0, bP < 0.001 versus Day 0, cP < 0.01 versus Day 0, dP < 0.05 versus Day 0, within respective groups.