Serum vitamin D receptor and fibroblast growth factor-23 levels in postmenopausal primary knee osteoarthritis patients

Abstract

Objectives: The role of vitamin D in primary osteoarthritis (OA) has not been clarified yet. vitamin D receptor (VDR) and fibroblast growth factor-23 (FGF-23) are proteins that play an important role in the metabolism of vitamin D. In this preliminary study, we aimed to examine serum 25-(OH) vitamin D3, VDR, and FGF-23 levels in primary knee OA patients. Methods: This study includes 60 post-menopausal women who were enrolled into two groups with primary knee OA (n=30, age range between 59.6 ± 5.7 years) and control (n=30, age range between 61.7 ± 6.3 years). Serum levels of 25-(OH) vitamin D3 were measured by chemiluminescence and serum VDR, and FGF-23 were measured by enzyme-linked immunosorbent assay methods. Results: In knee OA group, serum levels of 25-(OH) vitamin D3 were significantly lower (p=0.033), and serum VDR and FGF-23 levels were significantly higher than those of the control group respectively (p=0.000 and p=0.006). Also, FGF-23 levels showed correlations with 25-(OH) vitamin D3, VDR, and calcium levels (p<0.05). Conclusions: This is the first study showing a relationship between serum VDR and FGF-23 in knee OA patients. Extensive clinical studies are required to assess the applicability of these parameters in clinical practice.