ESPE Abstracts

Introduction and Aim: FGF-23 is a hormone that works by inhibiting phosphorus reabsorption in kidneys, and systematic regulation of phosphate homeostasis by FGF23 depends on the activity of the membrane protein Klotho. It affects the active vitamin level according to the bioactive free vitamin hypothesis, which binds DVBP to vitamin D and prolongs its half-life. In this study, it was aimed to investigate 1.25 (OH) Vitamin D, Vitamin D Binding Protein, FGF-23 and α-Klotho levels and how these parameters changed with the treatment of cholecalciferol in vitamin D deficiency.

Method: Patients with rickets were included in the study. Vitamin D, parathormone (PTH), calcium (Ca), phosphorus (P), alkaline phosphatase (ALP), Fibroblast Growth Factor-23 (FGF-23), α-Klotho, vitamin D binding protein (DVBP) levels in blood samples were examined before and after the treatment. The study was supported by Ataturk University Scientific Research Projects Coordination Unit (BAP) with project number 7181.

Results: 16 children under the age of 2 were included in the study. The average age was 8.57 ± 6.16 months. Two patients (13%) applied to our clinic with the hypocalcemic seizure. While serum Ca (P < 0.001), P (P < 0.001), vitamin D (P <0.01) levels significantly increased, serum FGF-23 (P <0.05), PTH (P <0.01) and ALP levels (P < 0.01) significantly decreased after cholecalciferol treatment. There was a positive correlation between serum FGF-23 and PTH levels (P <0.05).

Conclusion: Serum Ca, P, ALP and PTH levels reached normal levels with cholecalciferol treatment. FGF-23, not α-Klotho and vitamin D binding protein, plays an important role in rickets pathophysiology.