Multivariate regression analysis findings confirmed the positive association of wholePTH with 1,25(OH)2D/25(OH)D and 1,25(OH)2D/24,25(OH)2D ratios, as well as the positive association of FGF23 with 24,25(OH)2D/25(OH)D ratio and negative association with 1,25(OH)2D/24,25(OH)2D ratio, which further confirmed the critical role of PTH and FGF23 in regulation of vitamin D metabolism even in CKD patients. This evidence concerns the gene FGF23 and chronic kidney disease.