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Errors in reading DEXA by service providers
In the thread "Monitoring pH to encourage bone growth, which was started
2/10/08, Art wrote (on 2/17/08) as follows:
http://courses.washington.edu/bonephys/mis/opmistakes.html has
some
case studies on how to read a DEXA. Study those carefully -
when you have
your next DEXA you want to be able to look at the detailed
results and see if
there are any problems that your doctor may have missed. My
concern is that,
given your low score for your spine (-4.1) there may be some
compression
fractures. If so, their presence should play a major factor in
determining
what kind of exercises you can do safely.
I took his advice and studied the site carefully. It is dynamite, and
unsettling. We really do need to take our health in our own hands, and not
blindly accept what our providers tell us.
I had my follow-up DEXA on April 2, 2008 (as described in another post
today). I found that the scan had been analyzed in a manner that made
comparison with my March 2007 scan impossible. So I had to analyze the
detailed results myself, as Art had suggested.
The first error is that the 2007 DEXA results embodied L1 through L3,
omitting L4, but the 2008 results embodied L1 through L4.
The responsible person may have excluded L4 because it is misshapen. It is
thicker on the left side than it is on the right side, as if I had been
standing on my right leg all my life, giving a side-to-side curve to the
lower spine.
Truth is, I busted a tendon on my left kneecap when I was in seventh grade,
and unbeknownst to me the left leg grew 1.25" more than the right leg. So I
did in fact stand on my right leg a lot as I grew up, leaving the left leg
bent. I was 23 when a doctor noticed the difference in lengths. Ever since
then I have worn custom built-up shoes, but the damage may have already been
done to my growing spine, causing it to assume that shape.
The shape may also reflect compression fractures that caused a partial
collapse of one side later in life. Certainly the L4 bone mineral density
is higher than that of its neighbors. 2007 readings for L1-L4 are,
respectively: 0.651, 0.706, 0.791 and 0.957.
The inclusion of L4 in the 2008 analysis made it appear as though my spine
had improved. But when I looked in depth at the detailed results, I found
that I had actually gone backwards.
I noticed that the two DEXAs show slight variations in the estimated areas
of the individual vertebrae . These variations were necessarily reflected
by changes in the calculated bone mineral densities, even if the bones had
not changed at all. For example, dividing the BMC (bone mineral content)
for a given vertebra by a greater area will make it appear that the bone is
less dense.
The BMD (bone mineral densities) were therefore inconsistent, so I studied
the BMC instead. This took a fair amount of fussy work setting up an Excel
spreadsheet, but the results were then immediately apparent.
Changes in bone mineral content over the course of the year were as follows:
L1: -1.4%
L2: +0.2%
L3: -0.9%
L4: -0.5%
The same radiologist analyzed both DEXAs. He didn't catch the error, and
reported that there had been slight improvement in the spine. Indeed, based
on the faulty numbers, the plotted point for the spine in the rainbow
diagram had risen out of the Red zone (severe osteoporosis) into the orange
zone (marked osteoporosis).
The second error is that the femoral neck on the right leg were read in
different places, as clearly shown on the x-ray-like images.
So I studied just the left femur, which was read in the same place both
times. It showed that the BMC had changed by -1.6%.
The reported mean T-scores for the femurs came in at -2.4 both times, and
the radiologist reported that the results were unchanged.
These numbers are so bad that I would have come to the same conclusion as to
treatment even if I hadn't noticed the errors.
As you will see from my other posts today, my experiment with pH monitoring
was a success in terms of pH control, but in the face of these dismal
numbers, I must embrace a more aggressive approach toward improving bone
health. I will address the issue of low testosterone, and am now open to
starting medication.
2/10/08, Art wrote (on 2/17/08) as follows:
http://courses.washington.edu/bonephys/mis/opmistakes.html has
some
case studies on how to read a DEXA. Study those carefully -
when you have
your next DEXA you want to be able to look at the detailed
results and see if
there are any problems that your doctor may have missed. My
concern is that,
given your low score for your spine (-4.1) there may be some
compression
fractures. If so, their presence should play a major factor in
determining
what kind of exercises you can do safely.
I took his advice and studied the site carefully. It is dynamite, and
unsettling. We really do need to take our health in our own hands, and not
blindly accept what our providers tell us.
I had my follow-up DEXA on April 2, 2008 (as described in another post
today). I found that the scan had been analyzed in a manner that made
comparison with my March 2007 scan impossible. So I had to analyze the
detailed results myself, as Art had suggested.
The first error is that the 2007 DEXA results embodied L1 through L3,
omitting L4, but the 2008 results embodied L1 through L4.
The responsible person may have excluded L4 because it is misshapen. It is
thicker on the left side than it is on the right side, as if I had been
standing on my right leg all my life, giving a side-to-side curve to the
lower spine.
Truth is, I busted a tendon on my left kneecap when I was in seventh grade,
and unbeknownst to me the left leg grew 1.25" more than the right leg. So I
did in fact stand on my right leg a lot as I grew up, leaving the left leg
bent. I was 23 when a doctor noticed the difference in lengths. Ever since
then I have worn custom built-up shoes, but the damage may have already been
done to my growing spine, causing it to assume that shape.
The shape may also reflect compression fractures that caused a partial
collapse of one side later in life. Certainly the L4 bone mineral density
is higher than that of its neighbors. 2007 readings for L1-L4 are,
respectively: 0.651, 0.706, 0.791 and 0.957.
The inclusion of L4 in the 2008 analysis made it appear as though my spine
had improved. But when I looked in depth at the detailed results, I found
that I had actually gone backwards.
I noticed that the two DEXAs show slight variations in the estimated areas
of the individual vertebrae . These variations were necessarily reflected
by changes in the calculated bone mineral densities, even if the bones had
not changed at all. For example, dividing the BMC (bone mineral content)
for a given vertebra by a greater area will make it appear that the bone is
less dense.
The BMD (bone mineral densities) were therefore inconsistent, so I studied
the BMC instead. This took a fair amount of fussy work setting up an Excel
spreadsheet, but the results were then immediately apparent.
Changes in bone mineral content over the course of the year were as follows:
L1: -1.4%
L2: +0.2%
L3: -0.9%
L4: -0.5%
The same radiologist analyzed both DEXAs. He didn't catch the error, and
reported that there had been slight improvement in the spine. Indeed, based
on the faulty numbers, the plotted point for the spine in the rainbow
diagram had risen out of the Red zone (severe osteoporosis) into the orange
zone (marked osteoporosis).
The second error is that the femoral neck on the right leg were read in
different places, as clearly shown on the x-ray-like images.
So I studied just the left femur, which was read in the same place both
times. It showed that the BMC had changed by -1.6%.
The reported mean T-scores for the femurs came in at -2.4 both times, and
the radiologist reported that the results were unchanged.
These numbers are so bad that I would have come to the same conclusion as to
treatment even if I hadn't noticed the errors.
As you will see from my other posts today, my experiment with pH monitoring
was a success in terms of pH control, but in the face of these dismal
numbers, I must embrace a more aggressive approach toward improving bone
health. I will address the issue of low testosterone, and am now open to
starting medication.
