However, when the effects of FGF23 have been blocked with monoclonal anti-FGF23 antibodies in an experimental animal model of CKD, even if hyperparathyroidism was better controlled, the net result was a net increase in animal mortality [55], and these data cast some doubt on the putative direct pathogenic effect of FGF23. This evidence concerns the gene FGF23 and hyperparathyroidism.