Phosphate homeostasis, monitoring and managment of hyperphosphatemia in patients with the Chronic Kidney diseases

4. 1, 25 dihydroxycholecalciferol (1, 25 DHCC)

1, 25 dihydroxycholecalciferol is the activated form of Vitamin D. It increases intestinal phosphate absorption by enhancing the expression of NPT2b transporter and stimulates renal phosphate absorption by increasing expression of NPT2a and NPT2c in the proximal tubule. 1,25 DHCC also enhances FGF23 production. The 1,25(OH)2D also suppresses the synthesis of PTH and enhances FGF23 production. 

   Figure. Mechanisms contributing to decreased levels of calcitriol in chronic kidney disease

(C-PTH, Carboxyl-terminal parathyroid hormone; FGF-23, fibroblast growth factor-23; GFR, glomerular filtration rate; Pi, inorganic phosphate)