DEXA results error due to incorrect positioning

[Arcadia10]

I read Lani Simpson's excellent book Dr Lani's No-Nonsense Bone Health Guide a year or so ago and it really made me sit up and take notice of the errors that can creep into DEXA scan results due to a number of factors over which the patient has no control. We are led to believe that a DEXA is the gold standard in assessing bone density and as it is currently the only way of measuring bone density (besides the newer and not as financially and/or geographically-accessible REMS scan), we accept the results without question, as well as the resulting treatment which our doctors prescribe based on our DEXA results. My own experience earlier this year might serve as a warning to scrutinise and question any anomalous results.

When I had my DEXA on 6 March 2024 and before I even received my results, I felt that the technician had not taken enough care to position me correctly on the scanning table. Before my hip was scanned, my left ankle was turned inwards quite forcefully and tied to the block instead of rotating my hip and leg 15-20 degrees inwards as specified by Dr Lani in her book. I was actually just lying flat on my back with my hips and legs straight and my ankle turned inwards - that was it. The metaphorical red flags waved and I nearly said something at the time, but bit my tongue as I didn't feel that I should question the technician who I assumed had far more knowledge of the mechanics of doing a DEXA scan than I had after reading a book on the subject.

The results emailed to me a week later indicated that I'd lost 9.6247% BMD in my total hip since my DEXA of two years earlier (3 March 2022), so from -2.7 to -3.2. My femoral neck had decreased by 9.197%, from -3.0 to -3.5, but my spine had remained the same at -2.5. The red flags waved again and I decided to tell the densitometry clinic of my concerns and request a rescan, even if I had to pay for it in full myself as our health care system here in Australia only largely funds one scan every two years.

Eight days after my first scan, so 14 March 2024, I had a second DEXA on the same machine but by a different technician. This time, the utmost care was taken. Each area was actually scanned twice, with the technician (who I see had a Ph.D amongst her credentials!) going to consult with her manager in between scans. I was moved on the scanning table several times by the tiniest of margins and my left hip was rotated inwards very carefully and adjusted several times. Before I left, the technician told me in a surprised tone of voice that my results were better this time than the previous scan a week earlier. I was delighted!

When the results arrived by email a few days later, I found that my total hip was actually -2.9, not -3.2, so still a loss from two years earlier, but only 4.2414% instead of 9.197%. My femoral neck was -3.4 so a loss of 7.436% instead of 9.197% from two years earlier. My spine was -2.4 instead of -2.5.

It was an interesting exercise and bears out what Dr Lani stresses in her book - DEXA scans are an approximation of one's BMD and their accuracy depends on a number of factors and parameters, any of which being incorrectly applied could lead to an incorrect result. In my case, incorrect positioning of my hip led to my BMD result in this area indicating a decrease of .5 over two years when it was actually only .2.

Dr Lani's book is great and I'd recommend reading it to become as informed as possible about DEXA scans, what can go wrong when having one, and their interpretation. It might just prevent you from being prescribed unnecessary medication due to an inaccurate result.

[Hidden]

That’s all very interesting, thank you for posting!

[pussycatwillow]

I was not happy with a recent NHS Dexa scan for almost the identical reasons you mentioned, ie the skill of the technician. My results claimed I had osteoporosis.

I subsequently had a private REMS scan. No evidence of osteoporosis., just osteopenia which I know I have had for the last 15 years.

[Arcadia10 in reply to pussycatwillow]

I've read quite often that people who have REMS scans done have much better results than their DEXA scans indicate and, like you, are not actually osteoporotic. That just goes to show the margin of error that can happen in DEXAs which seem to be taken as gospel by most doctors.

I'm waiting eagerly for REMS scans to become available in my city, Perth. Unfortunately the nearest clinic doing REMS scans in Australia is in Melbourne, on the other side of the country about 4000kms away ☹️

[Arcadia10 in reply to Arcadia10]

Well, the universe moves in mysterious ways! I had an email out of the blue this morning from Cortex Health echolight.com.au/, the distributor of Echolight devices based in Melbourne, offering me a REMS scan in Perth next week. They will be here for only one day to introduce REMS technology to a clinic and a university, so I feel very fortunate. Melbourne is about 4,000 kms away, so I probably wouldn't have had the opportunity to have a REMS scan if they hadn't been visiting Perth.

This is very timely in regard to my recent debacle with my DEXA of 6 March 2024 which had to be repeated. I will post here with comparison figures once I have the REMS results.

[LilEgg in reply to Arcadia10]

I just saw your post. I wish you all the best! Warm regards Debbie

[Arcadia10 in reply to Arcadia10]

My REMS scan last week was very interesting - just like having a regular ultrasound with gel, etc. Only 16 people were scheduled to be scanned on the one and only day Cortex Health/Echolight was going to be in Perth, and I felt very privileged to be one of them. The intention of the owner of the business (who did the scans himself) is within 6 months to make Echolight scans available in the medical centre in which the scans were being done that day, so there was a doctor in training. I felt that the operator was very thorough. He scanned my lumbar spine twice, saying that I was a "unicorn" after the first scan. When I received my results today, I saw why.

Surprisingly, my lumbar spine which indicated a T-score of -2.4 in my DEXA of March 2024 returned a result of -2.0 in my REMS five months later. The T-scores of my L2 and L3 are also dramatically different comparing DEXA and REMS, indicating osteopenia instead of osteporosis (L2 DEXA -2.7; REMS -1.6 and L3 DEXA -2.6; REMS -1.7). There was a bit of debate on the day about excluding my L2 from the calculation as it is >1 SD from my L1, but I see in the report that all four vertebrae were included and, from my own (hopefully correct) calculations, I can't see that it would have made much difference anyway (-2.0 vs -2.13). I understand that these two large discrepancies are the result of my mild scoliosis affecting my DEXA results. REMS results are not affected by scoliosis as REMS uses ultrasound technology.

My left hip appears to have worsened slightly (by .1 SD) and, for the first time ever, I had my right hip scanned. The two total hips returned a very similar result. My left total hip which is -2.9 on my most recent DEXA is -3.1 on my REMS, and I see that my right total hip is -3.1 as well. At least they're the same which I understand goes some way to confirm scan accuracy.

My fragility (presumably bone quality) score is Lumbar Spine 31.1 which was in the green area on the graph, so good there. My Left Femoral Neck fragility score is 37.4 and Right Femoral Neck is 38.1, both in the red area, so not good there.

I also post on another site, Inspire.com, and have asked some questions and had some responses from the highly knowledgeable members there. A very useful point that was made is that one cannot use scans from different machines to measure change, whether it's from one DEXA machine to another, or DEXA to REMS. This is because of margin of error issues as well as because of the different technologies and different reference databases used by different manufacturers. So having a REMS scan means that one now has a separate baseline alongside one's DEXA history. You can't compare T-scores between DEXA and REMS and say that you've had an improvement or deterioration. That's disappointing as I was delighted when I saw my total spinal REMS results as I thought they were an improvement, but it's not a straightforward comparison, unfortunately.

I was recommended to have another REMS scan done in 6 months' time which I probably will do. The reason for this short-term scan is to confirm the accuracy of my first results as the margin of error is meant to be much smaller with REMS, so it is more capable of detecting and reporting small changes, and also to assess the ability of the technician to replicate my original results. So really just a double-check, which I'm quite happy to do.

I've tried several times to upload some images of my results in tabular form but they won't, for some reason. I'll try again later.

[MsHoliday]

Thanks for great advise. It’s been a while that I had my dexa scan. Well over two years and need the courage to request it. I will look out for Dr Lani’s book. It’s nice to see that you are doing ok. You helped me before to stay positive and great info when I was so nervous about everything! I feel like I’m doing ok but it’s good like what you have done to keep a check on things and keep up to date x

[Arcadia10 in reply to MsHoliday]

Nice to hear from you again, MsHoliday! So presumably everything went well with your weaning off Prolia, despite you being on the risedronate which didn't prevent my sacral and pelvic fractures. Are you off all osteo meds now?

I wouldn't be worried about requesting another DEXA. My (revised) bone density now is almost identical to what it was a month before starting Prolia in 2018 (apart from my total hip which has improved). This reverting to previous is what I understood would happen, although some people unluckily end up in a worse position than before Prolia. It was kind of reassuring to know the outcome and put the whole sorry episode behind me 😊

Hope all is going well with managing your PMR.

[MsHoliday]

Dear Arcadia10 thanks so much for your reply and your care. I’m off all meds now. I was so over all the side effects. I’m still being checked by heart specialist and last check a month ago showed absolute healthy heart. My blood pressure taken there was 130/70. He couldn’t believe it and took it again-same results The med story after the Prolia was the fibrillation causing a minor heart attack. Then at the hospital decided also to put me in high dose statins as well as heart medication and as a result low heart beat had Polymyalgia Rhumatica was put on prednisone; That resulted in infection and a dodgy root canal then decided not to have the risedronate that I was on for a couple of months. I was fortunate that I did not have the rebound fractures. My doctor showed annoyance regards not having the Prolia that I had a big note on my medical file about refusing medications etc and was on my referrals so I swapped doctors. I’m now at another medical practice and she only suggests and answers my questions but does not follow up with anything but that’s ok as I research all. I have aryuvedic herbals and try and incorporate a wide variety of calcium rich diet. Looking to get a vibration machine. I also walk 4 ks every day. But yes nervous and an hour train from Melbourne and interested in the new methods rather than Dexa. Apologies if this reads like a book The PMR and prednisolone is way over now and soo glad my body wants to heal. So happy to hear you are doing very well too!

[Arcadia10]

I'm sorry to hear about your tortuous health journey, MsHoliday, but glad it is all sorted now and that you didn't have any rebound fractures despite stopping the risedronate for a few months. Also great that you have now found a sympathetic doctor who listens to you. That is SO important. Taking meds or not is your choice and you're doing your own research and staying informed, which is great.

You're really fortunate to be living reasonably close to a centre that does the REMS scans. If I were you, I'd bypass the DEXA and go straight for that one next time you're in Melbourne, or even make a special trip echolight.com.au/booking/ It might reassure you regarding your choices about no meds for your bone density. I would jump at the chance but flying from Perth just for a scan feels a bit extreme to me. If I were going to be in Melbourne on holiday, I'd arrange beforehand to have a REMS scan done.

All the best then. Glad to hear that all is going well with you. Keep walking! I do about 30-40 km per week😊

[MsHoliday]

Thanks so much for info re clinic and well wishes Well done for your walking too! Xx

[ROSModerator Partner]

Hi all,

Thank you for sharing, we always ask members to be mindful how all of our healthcare journeys are different, so we really appreciate respectful discussions we see here in our online community. As discussions around REMS and DXA frequently come up in our community and sometimes note confusion around the topic, we put together some information in our Frequently Asked Questions pinned post that can be helpful to look through: healthunlocked.com/boneheal...

We hope that this may be useful for anyone coming across the thread 😊

All the best,

Lulu

ROS Moderator

[Kathleen1314]

Arcadia I saw that you were trying to get off prolia using actonel and then hoped to move to strontium citrate. Is that still your goal?

[Arcadia10 in reply to Kathleen1314]

I haven't gone back onto strontium citrate since stopping the prescription drugs, Kathleen1314. I'm trying to sort out an IBS issue and didn't want to complicate the process by introducing anything which could potentially increase constipation which I found SC did previously. If future scans indicate further bone loss which I feel I need to reverse, then SC will be my go-to. In the meantime, I'm following the COMB protocol of supplementation.