FGF23 and secondary hyperparathyroidism: Taken together, our data suggest that high-level Fgf23, hypophosphatemia and hypocalcaemia may have contributed to secondary hyperparathyroidism and osteomalacia in the SFFV-FGF2 animals, while low-level Fgf23 in the β-globin-FGF2 animals does not lead to a significant depletion of phosphate, thereby preventing osteomalacia.