Accuracy of DEXA Scans

Posted by njhornung @normahorn, Mar 9 7:07pm

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?

Interested in more discussions like this? Go to the Osteoporosis & Bone Health Support Group.

@normahorn

I trust that McCormick is using the term "clients' rather than "patients" when it comes to osteoporosis. Otherwise he might be crossing the line into practicing medicine without a license. When it comes to chiropractic, the term "patients' would be appropriate.

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@normahorn McCormick is a chiropractor so is "patients" appropriate?

@baguette this kind of detail in evaluating DEXA's was valuable for you. For some of us, the error rate isn't as important as the overall picture. In other words, for scores below, say, -3.5, I don't think error matters. I have been told that changes plus or minus -.5 are clinically significant, and my report also says not to use the femur neck score to evaluate changes. I have kept a chart of my DEXA's since 2001 and I look at trends rather than specific values. For me, considering issues with DEXA accuracy did not argue against meds!

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@windyshores

@normahorn McCormick is a chiropractor so is "patients" appropriate?

@baguette this kind of detail in evaluating DEXA's was valuable for you. For some of us, the error rate isn't as important as the overall picture. In other words, for scores below, say, -3.5, I don't think error matters. I have been told that changes plus or minus -.5 are clinically significant, and my report also says not to use the femur neck score to evaluate changes. I have kept a chart of my DEXA's since 2001 and I look at trends rather than specific values. For me, considering issues with DEXA accuracy did not argue against meds!

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The term "Patients" is okay if he is referring to his chiropractic patients. That may not apply to treating osteoporosis.

Accuracy is very important if one is asked to start a lifetime of medication based on a single DEXA.

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I was reading about DXA machines and it is recommended you go to a site with ISCD Facility Accreditation. I used their "location" feature and apparently there is none in the entire state of Colorado. Can that be right?? I emailed them and asked the same question. I can't find TBS software in the Denver metro area either.

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I don’t know anything about ISCD accreditation but there are no facilities in Minnesota, Texas or New York with that certification. I just checked them all on the ISCD site. Which means Mayo Clinic, Memorial Sloan Kettering, Columbia Presbyterian Cornell Hospital, and MD Anderson are certified - and that may indicate that the certification is not the one these excellent facilities are using.

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I am a newcomer and in my “research” mode. I found a good podcast that explains osteoporosis in general and after that there is a good discussion about DEXA screening, how to read and understand the report as well as the limitations and possible errors/misinterpretations, a lot of information I haven’t found elsewhere. I’m posting this now as I have been wanting to learn more about the use of DEXA screening. I haven’t finished listening to the entire podcast but will do so as I know there’s additional information about treating osteoporosis etc.

It’s a Mayo Clinic podcast:
https://open.spotify.com/episode/46lSyqxoGVre2918N6ldbt?si=dkqZJy3QRZCCPFw4HXpoiA

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