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Accuracy of DEXA Scans

Posted by njhornung @normahorn, Mar 9, 2024

I am guessing that I am not the only one facing a medication decision based on one DEXA scan with no fractures. That raises the question as to how much reliance we should put on that single measurement. I trust that sites calibrate the instruments according to the manufacturer's specifications. But we read about the importance of proper positioning. I was only asked to lie on a table with no special consideration of position. Does improper position make bones appear denser or less dense? Or is the effect minimal?

Remember the old weight charts that had ideal weight ranges by height and bone structure? Does DEXA factor in bone structure when calculating density. Obviously, there is less bone for the x-rays to penetrate for a fine-boned person than for a heavy-boned one. That could be interpreted has having less bone mineral density which may not be the case.

Any insight or other pertinent questions?

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dmr4ever | @dmr4ever | Jul 11 3:12pm
In reply to @triciaot "I’ve had the same question about smaller bones scoring lower numbers. This article says they’ve decided..." + (show)
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I’ve had the same question about smaller bones scoring lower numbers. This article says they’ve decided it doesn’t matter much (looks at men’s and women’s bone) when considering fracture risk.
Using the Same Bone Density Reference Database for Men and Women Provides a Simpler Estimation of Fracture Risk
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5101072/
The International Atomic Energy Agency has a publication all about the DXA bone scan:
https://www-pub.iaea.org/MTCD/Publications/PDF/Pub1479_web.pdf
This states that there are definite differences in the size and bone density of men and women and some populations, Asian is mentioned. It says that DXA looks at only 2 parameters and cannot determine a difference between a thicker less-dense bone and a thinner high-density bone.
It also states there can be about an 8% difference in scores from different machines.

I’ve felt unsure of my DXA scores as I have smaller wrist bones than many women of my height. Also because I don’t know anyone who has broken their hip, I’m 70 yo. My mother (osteoporosis) and 2 older sisters (both with osteopenia) have never broken a hip. Although my mother had some compression spinal fractures in her later years.

I did finally decide to start bone density treatment - which is a good thing because right at that same time I was diagnosed with breast cancer. Some of the bone density treatments can harden the bone against metastasis (and bone is one of the first places BC will often move to). So I see it doing double duty, increasing bone and deterring cancer.

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@triciaot
My bone density worsened with breast cancer treatment and aromatase inhibitors. I wish I had gotten a density scan prior to treatment. It seems like oncologists should add density scans to all the other scans prior to treatment. Thanks for sharing this.

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babs10 | @babs10 | Jul 11 3:41pm
In reply to @susankellynolan "@windyshores Hi, do you mind sharing what side effects you are having with evenity? I did..." + (show)
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@windyshores
Hi, do you mind sharing what side effects you are having with evenity?
I did 4 months of evenity, developed a toothache ( which ended up having to be extracted) & am wondering if dental problems are one of the side effects you are referring to.
Thank you!

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@susankellynolan, shoot! I hope Windy Shores is ok!

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