What makes one part of the body more of a target for bone loss?
September 14, 2011 11:38 AM   Subscribe

Why would bone density/changes in density be dramatically different in some areas of the body?

So I was on a medicine known to cause some bone thinning and I was tested for thinning, when the nurse get joking about how I was way too young to worry about that and got real quiet, I knew something was up. My wrists, hips, femurs, were within the normal mean. My lumbar spine was not.

Fast forward a couple of years, I stopped the medicine, exercised lots, took my CA and D, just got my new DEXA results in, wrists, hips, femur even thicker, nice and robust, yay. Lumbar spine? Moved virtually none. (-1.4 now -1.3)

My NP really has no idea and doesn't really understand why I care, she just wants me to go ahead and start the Fosomax, which I will. However, I like to understand things. What are some possible reasons that the lumbar spine would be particularly suscetible to bone loss? Why would that area be resistant to building mass back up?
posted by stormygrey to Health & Fitness (4 answers total) 2 users marked this as a favorite
Measurements of bone mineral density are wildly unreliable, especially comparing different tests run in different places. I don't personally have much faith in serial BMD measurements, and definitely not much faith in comparisons of different body parts.

In short, you are over-interpreting a famously unreliable test, of quite surprisingly uncertain validity.
posted by roofus at 2:48 PM on September 14, 2011

In addition, you might question why your NP is blowing off your concern and pushing you to take drugs - especially considering she "really has no idea" what's going on. Make her give you the label for Fosamax - the document that explains risks etc - and research it yourself as well (pharmaceutical labels are notoriously obfuscated) before you take it. For example, taking Fosamax can lead to bone loss or an increased risk of bone breakage - the very thing it's supposed to be helping prevent!
posted by attercoppe at 3:13 PM on September 14, 2011

Osteoporosis can accompany pregnancy, though uncommonly, and when it does, it tends to occur "in the upper lumbar or thoracic spine."

Some forms of hormonal birth control work essentially by imitating pregnancy, so if you happen to be using such, or have, that could possibly explain it.
posted by jamjam at 3:53 PM on September 14, 2011

Bone density tests? Not very accurate. If you're symptom free, just keeping up a sensible exercise regime would seem the best course of action. I'd avoid meds. Take a look at http://www.athleteinme.com/ArticleView.aspx?id=283. Extract: "The lumbar spine is 65% trabecular bone, while the femoral neck (the end of the thigh bone that connects to the pelvis) is 75% cortical bone (Duchman RL, et al. 2006). Research shows that exercise improves bone density in the spine more rapidly compared to other bones (Nelson ME, et al. 1994). At least 6-8 months of regular exercise is necessary to observe a response." There's plenty more there useful for you. Good luck!
posted by nickji at 1:26 AM on September 15, 2011

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