Cter-FGF23 peptides directly regulate iron metabolism in mice. Serum (A) cFGF23, (B) iFGF23, (C) i/cFGF23 ratio, (D) phosphate, (E) hepcidin, (F) iron, (G) TSAT, and (H) Hb in 6-week-old WT and Cter-Fgf23^Dmp1-cTg mice. Liver (I) Hamp mRNA expression, serum (J) hepcidin, (K) iron and (L) TSAT and (M) phosphate in 6-week-old WT mice 6 hours after administration of a single dose of 50 ng/g Cter-FGF23. Serum (N) cFGF23, (O) iFGF23, (P) phosphate, (Q) iron, (R) TSAT, and (S) Hb in 6-week-old WT and Dmp1^KO mice. Liver (T) Hamp mRNA, serum (U) hepcidin, (V) iron and (W) TSAT, (X) Hb, (Y) phosphate and (Z) 1,25OH₂D in 6-week-old FGF23^KO mice 6 hours after administration of a single dose of Cter-FGF23 (50 ng/g), IL-1β (250 ng/g), or both. n ≥ 5 per group. P < .05 vs (a) WT/Ctr, (b) Fgf23^KO + NaCl, (c) Fgf23^KO + Cter-FGF23, (d) Fgf23^KO + IL-1β.