Some quick points about Dexa Scans 1) Never until they are 65 yrs old (unless chronic steroid use or an indication that would make them high risk) 2) Never in the obese or overweight 3) After age 65 never again
Alright, let me see if I can explain this in easy to understand terms-
The confusing part for most people is why do it once and only once, why not more than once even though most societies recommend it.
REASON- ERROR IN THE TEST
For the sake of easy numbers lets just say a bone density in an average 65 year old is 100. (Yes, this is not the real number and use whatever units you want I am just trying to demonstrate with easy to understand numbers)
As I mentioned earlier the dexa scan has a pretty wide error of acceptable measurement. The dexa scan in a perfectly healthy individual would ideally read 100 but it could say a number somewhere between 90 and 110 and it would all fall into the 'standard of error of the test'.
Again, for easy numbers lets say the avg. rate of bone loss is about 2/yr.
So when you get a report that says 110 for bone density they could actually mean 90. Which is why when you check it the next year or a year later you might see 'a huge crazy insanely large drop' yet this is just a false drop as it fits in the error of the test and statistically there is no difference. Thus, if you have an avg. women and you want to test again and know that you are outside the error of the test you need to wait about 15yrs.
If you don't test till 65yrs old and you have to wait till the pt. is 80yrs old to get outside the error of the test, one must ask does an 80yr old really need to get a dexa scan??