There was an 18-fold increase in median FGF23 levels in children with vitamin D deficiency and a negative correlation between FGF23 and 25-hydroxyvitamin D. However, we did not have measures of active 1,25 dihydroxy vitamin D to assess whether elevated FGF23 was inversely correlated with activated vitamin D. Osteopontin is a glycoprotein expressed mostly by the bones and in varying amounts from other cells such as macrophages, smooth muscle, endothelial and epithelial cells and is involved in inhibiting bone mineralization (10, 11). This evidence concerns the gene FGF23 and vitamin D deficiency.