Characterization of FGF23 in transgenic EPO-overexpressing mice and beta-thalassemia intermedia mice. Groups included are wild-type mice (WT), transgenic EPO-overexpressing mice (TG EPO), transgenic EPO-overexpressing mice treated with a single intraperitoneal dose of 10 mg iron dextran 24 h prior to euthanasia (TG EPO + Iron Dextran) and beta-thalassemia intermedia mice. Parameters were measured at the age of 7–11 weeks for the WT and TG EPO mice, and at the age of 9–28 weeks for the beta-thalassemia intermedia mice, and include (a) hemoglobin, (b) serum urea nitrogen, (c) serum phosphate, (d) serum iron, (e) liver iron, (f) serum hepcidin, (g) bone Fgf23 mRNA expression, (h) marrow Fgf23 mRNA expression, (i) plasma C-terminal (total) FGF23, (j) plasma intact FGF23 and (k) percentage intact FGF23. *Denotes a statistically significant pairwise comparison versus the WT group (P < 0.05, with subsequent Benjamini–Hochberg correction for multiple comparisons). #Denotes a statistically significant pairwise comparison of TG EPO versus TG EPO + Iron Dextran (P < 0.05). Data are presented as mean and SD. n = 7–12 mice per group.