BMD after stopping strontium ranelate
J Bone Miner Res. 2006 Sep;21(9):1417-24. Theoretical Model for the Interpretation of BMD Scans in Patients Stopping Strontium Ranelate Treatment, Blake GM and Fogelman I. PMID: 16939400. Strontium ranelate (SR) is not FDA-approved for treatment of osteoporosis in the United States. However it is used in Europe and other countries. Strontium is incorporated into the bones and shows up on radiographs as a dense material—yet this extra density is not necessarily related to increased bone strength or reduced fracture risk. Thus, if standard bone density tests are done, and the testing facility is not aware the patient has taken SR previously, the test results could be deceptively high. The patient and physician could then think there is no osteoporosis or fracture risk, when indeed there is. The Blake and Fogelman study evaluated the theoretical long-term effects on bone density after individuals stopped taking SR. They estimated that 75% of the effects of SR on bone density were due to bone strontium content (BSC). This would mean that three years of treatment would lead to a spine BMD artifact of 11.2%, which would decrease to 3.8% in ten years. The total hip and femoral neck sites are also affected but by a factor of 0.65 and 0.53, respectively. The authors conclude: “Strontium ranelate treatment lasting for >6 months can affect BMD measurements for many years afterward.” Editor's comments: See this update on Strontium Ranelate for more information. The Blake and Fogelman study, and others done on SR, mean that people taking this medication need to be sure the bone density testing facility knows either that SR is currently being taken, or that it was taken in the past. The bone density test must then take into account this extra radiographic density to produce a valid test result. Note that an unadjusted 11.2% apparent increase in BMD after three years of SR would be roughly equal to what one would expect to gain in BMD after taking one of the approved bisphosphonates, such as Fosamax or Actonel. So this mistaken improvement in BMD could be quite significant.
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