Objective: This study aimed to determine the effect of calcitriol on serum concentrations of fibroblast growth factor-23 (FGF-23), sclerostin, intact parathyroid hormone (PTH), and handgrip strength in postmenopausal women with low bone mass.
Methods: A randomized, double-blind controlled trial was carried out among 141 postmenopausal women with low bone mass. Participants were randomized into two groups: 75 participants received calcitriol 0.5 μg/day and 66 participants received a placebo for 12 weeks.
Results: After 12-week calcitriol treatment, significant decreases in serum intact PTH (P =0.035) and sclerostin (P =0.039), as well as significant increases in serum creatinine (P =0.027), uric acid (P =0.032), 24-hour urinary calcium (P =0.0026), and left handgrip strength (P =0.03), were observed, compared to placebo group. Level of serum sclerostin was weakly but significantly positively correlated with serum PTH (r =0.277; P =0.01) and negatively correlated with 24-hour urinary calcium (r =−0.221; P =0.04) and left handgrip strength (r =−0.338; P =0.03) after calcitriol treatment. Multiple regression analysis demonstrated that decrease in serum sclerostin was associated with decrease in PTH serum level after calcitriol treatment (OR, 7.90; 95% CI, 2.28–27.42; P =0.002). However, no significant change in FGF-23 level was observed after calcitriol treatment.
Conclusion: Calcitriol treatment yields a considerable decrease in serum sclerostin and significant increase of handgrip strength, and the change in serum sclerostin is regulated by serum PTH and by muscle strength.
Keywords: calcitriol, FGF-23, fibroblast growth factor 23, handgrip, intact PTH, sclerostin