Serum Osteoprotegerin Concentration with Strontium Ranelate Treatment for Postmenopausal Osteoporosis: An Open, Prospective Study

Background: Strontium ranelate (SR) is a new antiosteoporotic agent with antiresorptive and bone-forming properties. The exact mechanism by which SR exerts its effects is not clearly understood. Bone resorption requires interaction between osteoblasts and osteoclasts. Osteoblasts produce a ligand for receptor activator of nuclear factor-κB (RANK). They also secrete osteoprotegerin, a decoy protein that blocks the interaction of RANK with its ligand, thereby inhibiting the differentiation and activity of osteoclasts. SR also has been associated with osteoblast proliferation and decreased osteoblast-induced osteoclast differentiation via increased osteoprotegerin messenger RNA expression in human osteoblasts.Objective: The aim of this study was to investigate the relationship between SR treatment and serum osteoprotegerin concentration in women with post-menopausal osteoporosis (PMO).Methods: This open, prospective study was conducted in women admitted to the outpatient endocrinology clinic of Baskent University Faculty of Medicine, Adana Medical Center, Ankara, Turkey, for the evaluation of PMO. Women with PMO who enrolled were administered elemental calcium 1000 mg/d and vitamin D 800 IU/d for 1 month before the study period. After obtaining baseline serum samples for determining osteoprotegerin concentrations, patients were assigned to the treatment or control groups at a 5:2 ratio and SR 2 g/d was administered to the treatment group. The control group continued to receive only calcium and vitamin D. Serum osteoprotegerin concentration was measured again after 3 months of treatment.Results: Thirty-five women (treatment group: n = 25; mean [SD] age, 59.80 [7.38] years; control group: n = 10; mean [SD] age, 56.60 [5.06] years) enrolled in the study. A total of 32 women—24 in the treatment group and 8 in the control group—completed the study. Compared with baseline, mean [SD] serum osteoprotegerin concentration did not change significantly after 3 months in either the treatment group (4.91 [1.24] pmol/L vs 4.71 [1.19] pmol/L) or the control group (5.36 [2.82] pmol/L vs 5.10 [2.19] pmol/L).Conclusion: The results of this small study found that serum osteoprotegerin concentrations were not significantly changed by SR treatment for 3 months among women with PMO.