The National Osteoporosis Foundation recommends that
all women over 65 years old, as well as all postmenopausal women
with at least one risk factor for osteoporosis have their bone mineral density
(BMD) tested. Why are we waiting this long? In our opinion, all women should be
carefully screened for risk of fracture at a much earlier age — no later than
age 40! Then, if their fracture risk assessment reveals concern, women at risk would
undergo bone density testing right away (if we could convince insurance companies
to pay for it). This would allow us to see when women need to take steps to improve
bone health, and give us a baseline to compare future tests against, so we could
and track how well their bone building programs are working.
Today, the most common way to look at bone mineral density is with a DEXA
scan (now often referred to simply as DXA). But rather than actually measuring the
density, this technology focuses low-energy x-rays from two different sources onto
the bone and measures the proportion of light rays that pass through the tissue.
These data are fed to a computer that plugs them into a formula to calculate an
average of the bone mineral content of any part of the skeleton, typically the spine,
hip, wrist, and femur. The theory is that the more light that passes through, the
less mineral mass present in the bone.
This test can be helpful in determining how “dense” bones are, but not
necessarily how strong they are. Nor do the test results tell us when we lost density
— it could have occurred in the remote past, or just last month. Our bones
naturally get thinner as we age, but keep in mind: thin doesn’t necessarily
mean you’ll fracture. Bone strength actually comes from its microarchitecture,
which is partly a function of genetics, plus its ability to self-repair, which is
largely a function of a woman’s life history and her whole-body wellness.
In other words, a woman may have
thin bones on DEXA, but have great architecture and capacity for self-repair
— and never fracture in her life.
This is another one of the problems with our current testing model: we give a woman
a number called a T-score, which is based on how she compares to the average
bone mineral density of a group of women between the ages of 20 and 29. If our bones
naturally get thinner as we age, of course a woman at 60 is going to have
a different T-score than a woman in her 20’s! Next, conventional medicine
gives a woman a diagnosis of osteoporosis if she is 2.5 standard deviations
away from this standard, and osteopenia if she deviates between 1.0 and
2.4 from the standard.
The more helpful and accurate measurement is the Z-score, which compares
your numbers against the average BMD for your age, sex, weight, and ethnic or racial
origin. But focusing on the T-score is the gold standard for today’s practice.
This is a shame because many women are diagnosed with osteoporosis and osteopenia,
and believe they need to immediately go on
Fosamax or some other powerful drug to preserve their bones, when this may
in reality be unnecessary.
The truth is we can maintain strong and healthy bones throughout life with quality
plenty of exercise. So scrutinize all your fracture risk factors; if possible
get tested while still in early perimenopause, so you can use your score as a reference
point for interpreting future test results; and place your DEXA results in the context
of other women your age. If you’re interested in tracking your bone health
on your own and cannot justify the out-of-pocket expense for DEXA (whether early
or not), you might consider NTx testing.
See our articles on osteoporosis and
bone health for more information.
Start reducing your risk
of bone loss and fracture