Human clinical trials have documented individual bone sites reaching a substitution rate of 4.5% (and slightly higher) of strontium for calcium, though it is not a whole-skeleton average.
In clinical trials for the osteoporosis drug strontium ranelate, paired bone biopsies of postmenopausal women treated for 36 months showed that strontium was exclusively incorporated into newly formed bone. In these specific, newly mineralized bone packets, the mean substitution rate of calcium by strontium ions was 4.5%, with some individual tissue samples revealing that up to 10% of calcium atoms (1 out of every 10) were replaced by strontium in the apatite crystal lattice.
However, across the entire skeleton, the average retention is much lower—typically plateauing at around 1.5% to 2.0% of total bone tissue weight after 3 years of therapeutic dosing.
The DEXA Scan "Illusion": Strontium has a much higher atomic weight than calcium (87.6 vs. 40.1). Because it blocks X-rays far more effectively, every 1% of strontium substituted into the bone crystal causes a DEXA scan to overestimate bone mineral density (BMD) by roughly 10%. A person with a 5% substitution at a specific hip or spine site would see an artificially inflated BMD reading of up to 50%. Servier, the original manufacturer of strontium ranelate, stated that, after three years on strontium ranelate, BMD changes measured by DEXA scan could be inflated by 50%.
https://pubmed.ncbi.nlm.nih.gov/19874195/
https://pmc.ncbi.nlm.nih.gov/articles/PMC4708970/
2 comments:
Great information! But the math is off some, and the quote from Servier leaves out key words: it was 50% of the observed increase in BMD. The 4.5% biopsy figure is just a local micro-measurement. DEXA scans measure the whole bone thickness, where the global average plateaus at 1.5% to 2% . With the 10% rule, the actual inflation is around 15% to 20%, not 50%.
To: Anonymous of October 21, 2026
I will add "changes" to the quote from Servier: Servier, the original manufacturer of strontium ranelate, stated that, after three years on strontium ranelate, BMD changes measured by DEXA scan could be inflated by 50%. https://pmc.ncbi.nlm.nih.gov/articles/PMC2699648/
No, DEXA scans do not measure the whole bone thickness. A DEXA scan does not measure the actual physical thickness or depth (three-dimensional volume) of a bone. Instead, a DEXA scan measures bone mineral density (BMD), which is a two-dimensional areal measurement—essentially calculating the amount of calcium and other minerals packed into a given area of bone (expressed in grams per square centimeter, or g/cm²). A DEXA scanner passes low-dose X-rays through the body and creates a flat, 2D shadow-gram image of the bone (typically the hip, lumbar spine, or forearm).
Across the entire skeleton, the average retention of strontium typically plateaus at around 1.5% to 2.0% of total bone tissue weight after 3 years of therapeutic dosing. However, the entire skeleton is not measured. Specific bone sites are measured by DEXA scan and can retain far more strontium.
"The fluorescence results show that only bone packets or osteons formed during the strontium ranelate treatment contain significant amounts of strontium and that up to 0.5 of 10 calcium atoms (5%) in the mineral crystals are replaced by strontium, as revealed by a corresponding shift in apatite lattice spacing." https://pubmed.ncbi.nlm.nih.gov/19874195/
I have been taking strontium citrate for nearly 19 years with no side effects and no fractures. My BMD results have increased with each DEXA scan. So, I know the strontium is getting into my bones to make them stronger. I am very happy with strontium citrate and do not care what my "real" BMD numbers are. All correction percentages are estimates, and the actual BMD numbers will vary for each site tested in each individual.
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