Han N, et al. – In this assessment, the clinicians explored the effect of additional calcium carbonate treatment on fibroblast growth factor 23 (FGF23) levels in patients treated with calcitriol. Their investigations displayed that additional calcium carbonate treatment significantly increased serum FGF23 levels in patients treated with calcitriol, with their synergistic effect in promoting intestinal calcium absorption. Therefore, serum FGF23 levels should be monitored regularly, especially in those who use the combination of vitamin D and calcium carbonate from the early stages of chronic kidney disease (CKD).