UNLABELLED: Objective To evaluate the effect of strontium ranelate (SR) on bone turnover markers in women with established osteoporosis previously treated with teriparatide (TPTD--recombinant human PTH 1-34). DESIGN PATIENTS: Twenty-two postmenopausal Caucasian women (aged 65.7 +/- 1.7 years) with established osteoporosis previously treated with TPTD 20 microg daily for 18 months were randomly assigned to receive either SR (SR group, n = 11) or calcium and vitamin D (control group, n = 11).MEASUREMENTS: Blood samples for serum N-terminal propeptide of type 1 collagen (P1NP), C-terminal telopeptide of type 1 collagen (CTx) and total alkaline phosphatase (ALP) were obtained from all women before (pre-TPTD) and after (post-TPTD) TPTD administration, as well as 6 months after SR or calcium/vitamin D administration (post-SR/Ca).RESULTS: Serum P1NP, CTx and total ALP increased significantly after TPTD treatment and decreased at the end of the study in both SR and control groups, with no difference between them.CONCLUSIONS: SR following TPTD administration acts predominantly as an antiresorptive agent with no evidence of additional osteoanabolic action. In this setting, SR is not more effective than Ca/vitamin D as far as bone turnover markers are concerned.