Short-term bone marker responses to teriparatide and strontium ranelate in patients with osteoporosis previously treated with bisphosphonates.

OBJECTIVE To evaluate the responses of serum beta-CTX and osteocalcin in patients who were undergoing treatment with teriparatide or strontium ranelate (SR). SUBJECTS AND METHODS We analyzed 14 patients (12 women and 2 men; mean age of 71 years) taking teriparatide, and 13 female patients (mean age of 70 years) taking SR; all the patients having previously been on bisphosphonates. Serum beta-CTX and osteocalcin levels were determined before and after the first and third months of teriparatide treatment and up to the fourth month of treatment with SR. RESULTS We observed an initial significant increase in osteocalcin levels during the first month (165%, p = 0.01) followed by a peak of beta-CTX (180%, p = 0.02) after the third month of treatment with teriparatide. An increase in these markers was also observed with SR: 49% in osteocalcin (p = 0.002) and 80% in beta-CTX (p = 0.008). CONCLUSION SR had a predominantly short-term bone-forming effect in postmenopausal women with osteoporosis previously treated with bisphosphonates in a lesser degree than with teriparatide.