Did you know that bone density testing facilities are not required to have certified trained technicians?
Also, the doctor reading the exam is not required to be certified as a densitometrist?
Training is voluntary!
Any MD can issue a report on a bone density test. This is a huge problem, densitometry is not a required field of study in radiology or medical training. I review cases from all over the country and I find preventable errors many times a week. When a report incorrectly concludes that bone loss has occurred, that is often a trigger for the doctor to prescribe a medication.
“errors are not uncommon”
International Society of Clinical Densitometry
Before reading further about comparison errors I want to make it clear where I stand about bone density testing (DXA). DXA testing is an excellent tool, especially when you have an initial test. Even if you have a 5% error you will be in the ballpark. In other words, if you have significantly low bone density this test can help save you from fractures in the future if your doctors use this along with appropriate lab testing and a comprehensive bone health program that includes nutrition, gastrointestinal health, exercise and appropriate medication when necessary. My book, Dr. Lani’s No-Nonsense Bone Health Guide goes into much more detail about testing and risk factors for osteoporosis. These risks factors should prompt you and your doctor to discuss getting a DXA scan. My book also highlights new ways to think about bone health and fracture reduction, which is the name of the game.
Following are real cases that I have evaluated. The names have been changed for confidentiality.
Case study #1
Melanie was diagnosed with osteoporosis. She was frightened to hear her diagnosis. Her bone density T-score is – 2.5 SD (translation – 30% less than an average 30 year old or borderline osteoporosis). She has never fractured a bone and she is 58 years old. She eats a healthy diet and exercises. Her doctor told her that she has lost 2% bone density and that she has moved from osteopenia (low bone mass) to osteoporosis. No family history of hip fractures or osteoporosis.
Her doctor recommended that she take Fosamax. Melanie is active and wants to stay that way, but she is concerned about the side effects of Fosamax. Should she take Fosamax? As a chiropractor I cannot tell her not to take the medication. What I can do is assess her case as a densitometrist. First and foremost, 2% bone loss or gain is not a reliable number. The least significant loss or gain is in the neighborhood of 5%. My personal view is that Fosamax has side effects that should be weighed carefully before embarking on such medications. I interviewed, Dr. Jennifer Schneider regarding the use of Fosamax. When I first heard Dr. Schneider speak on a Diane Sawyer interview I knew I wanted to have her on my webinar program. It is free to view on my website.
Case study #2
Frank was told that he lost 5% bone mass in a five-year period. The report was flawed because the radiologist who wrote the report compared the neck of the femur to the total hip, which was an error. When compared correctly he had not lost bone and in fact, his bone was stable.
Case study #3
Rita came to see me. She was concerned about the state of her bones. She is 68 years old and was told that she had lost 5% bone density since her last exam. She asked me for a second opinion regarding her scans. First, the two machines were from different imaging centers. There can be as much as 7% difference between two different machines, even if it is the same company. The second issue was the first center made an unforgivable and elementary error. The technologist selected the wrong region in the lumbar spine. Normally this test includes four of the five lumbar vertebra (L1- L4). Instead they selected the last thoracic vertebra and the first three lumbar vertebra. The doctor who approved the report certainly should have caught this error. Bottom line, the test was not comparable.
Case study #4
Susan was told that she lost 7% bone mass in her hip. The hip rotation was incorrect in her previous exam. This rotation error is a common mistake, but should have been easily caught by the technologist and if not the technologist the doctor reading the exam. Improper hip rotation can result in up to a 10% error with either an increase or decrease in bone density.
Rachel was told she had lost bone in her lumbar spine. On closer examination in her first bone density exam in 2008, the technician selected lumbar vertebra L1-L4 (this is correct) and in 2012 the technician selected T12 through L3. Since vertebral bones get larger from the top to the bottom of the vertebral column, the mistake showed she lost bone. I called the radiologist and told him about the error and mentioned that the technologist needs to first identify L4 and count from the bottom up. He said at their facility they count from the top down. It was obvious that neither the radiologist nor the technician had been trained in densitometry.
Sahara called to tell me that she took a supplement that increased her bone density by 2% in one year. If you have read this far I think you know the answer to this one. The 2% is not a reliable number. Also, there is a lot of hype on the Internet regarding supplements increasing bone density. These claims are FALSE!!! If someone has a deficiency in vitamin D, calcium or has fixed a digestive disorder then yes, a modest gain may be seen over a two to three year period in bone density comparisons. Small studies on websites that I have seen, such as a popular calcium supplement made from algae are not reliable. For instance the study group on one site used subjects with a wide age range from 18-85 - This borders on ridiculous. In fact, many older people who have arthritis will show and increase in bone density simply because their arthritis is worsening.
Errors on bone density exams? Isn’t bone density testing reliable?
Bone density testing is only as good as the technician’s ability to set up the patient correctly and the doctor’s ability to evaluate and assess the data that the computer analyzes. The least significant change that is reliable when comparing two bone density exams is around 3-5%. This is because the machine itself is not perfect every time and the technician can make slight errors when setting up the patient. Such errors can result in an exam of a patient that appears to have lost or gained bone density. When the treating doctor reads the report furnished by the bone density exam center they rely on these reports to determine whether or not to prescribe medications.
Some facilities are doing great work. For instance in the San Francisco Bay Area – The Foundation for Osteoporosis Education, UCSF in San Francisco and The Northern California Institute for Bone Health in Orinda, CA. The doctors who read these reports have been trained and they are certified clinical densitometrists. You can ask your facility whether or not the tech and the doctor reading the exams are certified. While this does not remove all errors, it is a huge step in the right direction.
What if your facility does not have a densitometrist? Some doctors still do a good job with reporting, however if you question the results get a second opinion from a densitometrist. The error rate for some facilities is much lower than others due to excellent training of technologists and reporting doctors. For example, I am the reporting doctor (densitometrist) for the Foundation for Osteoporosis Research and our least significant change is about 2.5%. Not all facilities have established their least significant change as it is expensive for an imaging center to do so.
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