Effect of Cholecalciferol therapy on serum FGF23 in vitamin D deficient patients: a randomized clinical trial.

Background: Fibroblast growth factor-23 plays an important role in regulating systemic phosphate homeostasis, and vitamin D metabolism. However, the effect of Cholecalciferol therapy on FGF23 serum level in patients with vitamin D deficiency has not been studied, yet.

Methods: This is a double-blind, randomized clinical trial on 119 vitamin D deficient patients in 2016. Biochemical variables of treatment and placebo groups were analyzed after 12 weeks of 50,000 IU of Cholecalciferol vs. placebo therapy once a week, by SPSS18.

Results: After Cholecalciferol therapy, delta of serum PTH in treatment group was less than the controls (P < 0.001). However, delta values of serum 25(OH)D3, 1,25(OH)2D3 and FGF23 in vitamin D treated group were more than the placebo-treated ones (P < 0.001, P = 0.002, and P = 0.04, respectively). Moreover, FGF23 serum level in treatment group was associated with serum calcium (P = 0.005, r = -0.256), and serum 1,25(OH)2D3 (P < 0.001, r = 0.529).

Conclusions: We propose that in these patients 1,25(OH)2D3 has a positive association with serum FGF23, and hypostasized that serum calcium might be a down regulator of serum FGF23.