| Introduction
There have been several recent new recommendations regarding
screening for osteoporosis. I will attempt to summarize the latest
recommendations here. First, we will all need to understand a few
terms. This is a little complicated, but bare with me and
hopefully this will all make more sense.
Definitions
Bone Density or Bone Mineral Density: the average
concentration of mineral (calcium) in a x-ray image of bone. It is the
result we obtain when we measure your bone density.
Osteopenia: a term that means there is a decrease in bone
density, but not severe enough to call osteoporosis. By
definition it means your 'T-score' is between -1.0 to -2.5 standard
deviations below normal for a person of your same sex and of age 25-45
years.
Osteoporosis: a more marked decrease in bone density, it is
defined as a 'T-score' of -2.5 standard deviations or below. It
is also defined by the presence of a vertebral fracture on an x-ray.
Standard Deviation: when you measure things such as blood
pressure, temperature, pulse, weight, height or bone mineral density
in a group of people you will get a lot of different results. If you
average them you then know about where the middle of the group lies.
Some people will be above and some below the average. Standard
deviation is a way of talking about the amount someone is above or
below the average. Two standard deviations above and below an average
will generally include about 95% of the people. So, deviations
above 2 standard deviations imply you are a little unusual
statistically. We often get concerned at this point.
T-score: the difference between your bone mineral density
and the average density of a group of women, with presumably optimal
bone density, averaging ages of 25-45 years old. Example: suppose your
T-score is -1.5. This means your average bone mineral density is
1.5 standard deviations below a group of women aged 25-45 tears old.
Z-score: the difference between your bone mineral density
and the average density of a group of women your same age.
Why Are We Concerned About Osteoporosis ?
When women reach menopause, either naturally or by removal of the
ovaries, there develops a fairly rapid decline in bone density as the
estrogen levels decline. This loss of bone is quite rapid in the
first 7 years after menopause. This loss of bone then slows down, but
continues for the life of the woman. As time progresses, if you
live long enough, you will become osteopenic and later osteoporotic.
Some groups are less prone to this including non-white women and men.
When your bone density decrease you become at increasing risk for
fractures of various bones. The most common osteoporosis related
fractures are of the vertebrae in the spine, hip, wrist, and
ribs. You can also break other bones. These fractures can be
related to trauma, but some times occur with very minimal or no
trauma.
These fractures produce a variety of problems. The most obvious is
pain, decreased mobility, decreasing height, need for major surgery
with the risks of blood clots, pneumonia, bladder infection, nursing
home related rehabilitation, and death. Current estimates
suggest osteoporosis costs our health care system 13.8 billion dollars
annually (this is 7 year old data, so it is probably more now).
Who Should Be Screened for Osteoporosis ?
- White women who are postmenopausal over age 64.
- Postmenopausal women under age 65 who have one or more risk
factors for osteoporosis.
- Postmenopausal women who have a fracture of any type after age
45 years of age.
What are the Risk Factors for Osteoporosis ?
- A parental history of hip fracture.
- Current cigarette smoking.
- Body weight under 125 pounds.
- The use (or plan to use) prednisone or other steroid pills for
over 3 months.
- Serious long term medical conditions known to increase the risk
of fracture such as: hyperthyroidism or malabsorption syndromes.
Which Test Should Be Performed ?
The dual photon absorptiometry study is best for looking at the
hip. It will give the best prediction of your risk for hip
fracture. The computed tomograpghy study of the spine is the
best predictor of disease in the spine. It is recommended especially
for people who will be taking prednisone or other oral steroids.
Medicare will generally only pay for one of these studies. In
general, you should one or the other study.
The dual photon absorptiometry study will measure the density of
the spine also. However, due to the nature of the study it may
show a normal density when the density is actually low in the spine.
Measurements of areas such as the wrist, finger, and heal are
useful, but in general, are not as good at predicting your risk for
hip fracture.
Conclusion
You should consider your risk for osteoporosis. If you
believe you would be interested in treatment if your bone density were
low, then you should consider being tested if you are at increase risk
for osteoporosis.
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