In CKD stage 2, elevated serum sclerostin (z-score: 0.97), total fibroblast growth factor 23 (FGF23) (z-score: 0.72) and alkaline phosphatase (AP) (z-score: 0.61) concentrations were observed in association with reduced serum phosphate (z-score: -0.62) and 1,25-dihydroxy vitamin D<sub>3</sub> (1,25(OH)<sub>2</sub>D<sub>3</sub>) (z-score: -0.80) and a high prevalence of vitamin D deficiency or insufficiency (80.3%). This evidence concerns the gene FGF23 and vitamin D deficiency.