Frequently patients present to me with their DEXA scan asking me what they can do to prevent osteoporosis. Recently I had one such patient who presented with a peculiar situation. For several years she had been attending a local health fair that included a ‘wellness’ blood testing screen as well as a cursory DEXA scanning to determine her bone density. She was concerned because her most recent bone scan (DEXA) showed that she was modestly osteopenic in her wrist and osteoporotic in her hip. This isn’t unusual, but in her case it was. You see she was only 40 years old! She had had a major joint replacement surgery within the last year and was just beginning to deal with a thyroid problem. Now, this news of osteoporosis had her scared and confused. Was she really aging that rapidly? Would she be dealing with the debility and pain of broken bones and compressed vertebra before her kids finished high school? She needed information, so we talked. Here’s what we talked about.
DEXA scans have two numbers that they give you. A Z-score and a T-score. A T-score is where they compare your bone density against the bone density of a sex and ethnicity matched (in this case white female)30 year olds (someone at their highest bone density potential). Or to restate, they compare it against a baseline perfect score. The T-score is given as a numeral that compares you to that given optimal score (which is given as Zero). So in this case her hips T-score was -2.6 (that’s negative 2.6). So what that means is that her bone density is a little over two and one half points deviated from the norm. If your T-score is more than 2.5 points under the norm of 0 (zero), then you will be officially designated as osteoporotic. If you have a history of recent bone fracture(and a T-score below -2.5) or are more than 3 points below the norm of zero you are officially SEVERELY osteoporotic.
Now, she also had a T-score of -2.0 in her wrist. A T-score between -1.0 and -2.5 is what is medically termed osteopenic. Osteopenia means hungry for bone or wanting for more bone. So parts of her skeleton were officially problem areas and others were awfully close. That was concerning for her to say the least, and me because I’m the doctor that takes care of those bones and nerves manually. You certainly don’t want overly aggressive chiropractic technic on brittle bones….OUCH!
But before we get too far we should discuss the z-score. Z-score compares you against people your age (and sex and ethnicity). So as expected her numbers were again below zero. What does this mean? Well, loss of bone density is something that occurs naturally over the course of time, just like wrinkles and well you get the picture. So its pretty much expected that by the time you reach ninety years of age that your T-score would be under -2. But if you compared a 90 year old against average 90 year olds they should be pretty similar right? Exactly! So if your t-score is below normal (lets just say -2 or under) your bones are aged compared to a 30 year olds. But if your Z-score is below -2 then you have a problem that is more than just normal aging!
What would happen if you went to space for 3 months? Well, you would do TONS OF EXERCISE! Why? Because if you didn’t put you skeleton under some stress it would deteriorate! Remember, there’s less gravity in space! Therefore there’s less stressing your bones. Bones under less stress do not remodel and remain strong! Most long mission astronauts become osteopenic or porotic in a matter of weeks simply from the reduction of gravitational stress. Have you ever wondered why they show images of astronauts being helped out of their space capsule upon their return? They’ve lost bone density and muscle strength while they were gone. So, if you’ve ever wondered why astronauts are always riding a stationary bicycle in space, its to prevent sarcopenia (muscle wasting) and osteopenia (bone wasting).
Anyway, back to the story…
I spoke with my patient about her treatment options and some inconsistencies that I had seen in her scans. Her previous years scan had scanned her left wrist and then the following year her right wrist and then the next year back to her left. I found that quite confusing? You see, bone scans should ALWAYS be consistent. Measure the same thing the same way EVERY time. In fact, use the exact same machine as you used previously if you can.
Not all DEXA scanning machines are equal, just like some camera’s are inherently better than another some scanners are too. Good quality bone scans will measure the hip and spine primarily. Other machines will only test the wrist or heel and make educated assumptions from that. I was beginning to think that the machine being used for this health fair (or the technician running it) wasn’t that great. So I suggested she receive another scan from a reliable machine at a consistent location that she could follow up with in the future as needed. We decided on the local hospital’s machine and her results were interesting. END PART 1!