- FGF23, PTH, and phosphorus levels were higher in more advanced stages of CKD, while serum calcitriol levels and phosphate reabsorption rate were lower. - A significant inverse correlation was found between eGFR and FGF23. - FGF-23 was inversely correlated with serum phosphate levels. - High FGF-23 was independently associated with increased time on corticosteroids, increased PTH, increased serum phosphate, and decreased calcitriol. - Higher FGF23 values were not correlated with increased phosphate excretion. This evidence concerns the gene PTH and chronic kidney disease.