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Accuracy of DEXA Scans
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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May I ask how old you are? I'm 59 and had significant deterioration from my last scan. Am at -3 for femoral neck, -2.5 hip, and -2.7 L1-L4. Am healthy, exercise 3-5 times a week, lift weights, eat well. Am being referred to an endocrinologist, but can't get in until May. Trying to learn and understand. Feeling kinda bummed and confused on what I do until then.
Was first diagnosed when I was 40 and changed diet and got to osteopenia range. Then this surprise. Am on HRT. I declined taking boniva at the time because I didn't want to be on a med that didn't have trials for long periods of time.
Had couple of fractures when kid, but nothing since.
Open to all guidance any of you have on how to navigate and sort through all the info.
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1 ReactionThank you!!
Sounds like you did your due diligence and came up with a reasonable treatment plan that gives you the best chances of building bone under your particular circumstances. That's the best any of us can hope for.
How long and what type of hrt if you don’t mind me asking?
@jcounts, you have to use the, @plusname, to direct your question to an individual post. See how I used your account name? This way, hopefully, your email will show there was a response.🤎
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2 ReactionsDid your doctor recommend Reclast? And why not Zometa? Are you taking it for bone mets or to prevent it? Thank you.
My MD Anderson rheumatologist and local Baylor Scott & White endocrinologist both recommended Reclast. I do not have bone mets. My spine and one hip was at -2.9, I’ve been at osteopenia for probably 15 years, so I need something. Since DCIS is known to recur, even if my percentage has been lowered by radiation and tamoxifen, I was okay with taking Reclast as it hardens the bone against mets. Those percentages are statistical numbers, not 100% accurate. It just seemed to make sense to take the med.
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1 ReactionI posted in the Evenity side effects thread about my talk with McCormick today. Basically, the last 6 months of Evenity as an anti-resorptive are much more potent than those 6 months on Reclast, he said, especially for the femur neck which is cortical. I am going to check with my doctor.
McCormick said he has 55 patients on Evenity. He previously said 40% have some joint pain and today said only one had pain after stopping.
My P1NP is low which could mean it isn't working well and also reflect the half dose. McCormick suggests, despite my considerable side effects, that I try a full dose again, or possibly talk to doc about 1/2 dose every two weeks, wait two months and do a P1NP then.
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.
njhornung @normahorn. There is a lot of discussion by MDs about positioning and other factors leading to improper DEXA scans. I had a bad DEXA scan, but my PCP and gyno just went by the bottom DX from the radiologist that I had severe OP. They both wanted me on drugs ASAP. I hesitated, after figuring I had OP because of a drug previously prescribed (omeprazole for GERD). While hesitating, I fell about half a dozen times, no fracture. I read McCormick's book on OP, which said if there was a standard deviation between high and low values on the scan, throw out the low value. There was such a deviation. Between the book and my experience, I gambled with not taking drugs. After two years I saw Dr. Bush for a REMS scan. Before the scan he looked at the DEXA and said toss out the TWO lowest scores because of deviations between high and low, and I had osteopenia. The REMS scan also came up osteopenia. There was something wrong with the DEXA scan. If you can find a knowledgeable health care provider who can read scans properly, you may want to do a second reading for peace of mind. McCormick does that if you don't know anyone locally. I wouldn't recommend home-based OP tests of falling, like I did! I hadn't fallen in years until I got that severe OP DX. Talk about your subconscious taking over! I don't know how common the wrong DEXA is, but a second opinion by someone versed in reading them may be worth it. In my case, Dr. Bush said my two lower vertebrae were rotated and that may have caused the problems. He also noted that I am small person, and that may have an effect too.
Here is an excerpt from the NHI: Precision error is inherent in the BMD measurement itself and is largely dependent on the skill of the technologist in placing the patient in the same position for different scans. Precision represents the reproducibility of the BMD measurement and is typically calculated by measuring BMD in 15 patients three times or 30 patients twice on the same day, repositioning the patient after each scan. The LSC, a value that is derived from the precision calculation, is the smallest BMD change that is statistically significant with a 95% level of confidence. Unfortunately, many DXA facilities have not done precision assessment, and quantitative comparison of BMD measurements cannot, therefore, be performed. Furthermore, there is often a lack of adherence to manufacturers’ recommendations for device maintenance and quality control, and the education and training of bone densitometry technologists and interpreters varies widely. For all these reasons, mistakes in BMD testing are commonly seen (Table 1), sometimes with adverse effects on patient care. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3891842/
I got lucky that my DEXA scan was wrong and I followed a hunch and had access to someone who could read the scan properly. Not all the scans are bad, so I wouldn't say that they should be ignored. But if you have doubts, find a way to confirm or not.
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