FGF23 and hyperphosphatemia: It is known that hypervitaminosis D, hyperphosphatemia, and increased circulating PTH stimulate Fgf23 secretion in bone.18 However, serum PTH and phosphate remained unchanged, and serum vitamin D hormone concentrations were actually suppressed in our experiments, suggesting that other factors must be responsible for the increase in serum FGF23 post‐MI.