Levels of serum sclerostin, FGF-23, and intact parathyroid hormone in postmenopausal women treated with calcitriol

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.