It is well conceivable that the immediate increase in the serum 1,25(OH)2D3 concentration due to a glucocorticoid-dependent downregulation of FGF23 is overridden by further direct and indirect effects of glucocorticoids on the bone and vitamin D metabolism in the long run resulting in the well-documented bone loss and vitamin D deficiency. This evidence concerns the gene FGF23 and vitamin D deficiency.