Why Should You Get Your Bone Mineral Density Checked?

3D CG rendered image of healthy / osteoporosis bone micro structure

Bone density, or how thick your bones are, is presently tested with a bone mineral density test (BMD). The World Health Organization (WHO) has established specific guidelines about what constitutes abnormal bone mineral density. These guidelines are based on how far off the patient’s results are from those of the typical healthy young girl, using something t scores.

Osteoporosis

Osteoporosis is defined as a t score of less than -2.5, which corresponds to a noticeable degree of bone reduction. For those who own a t score of less than -2.5, you’re in the bottom 1 percent in terms of bone density. Osteopenia is bone loss which isn’t as intense as osteoporosis, and is described as scores between -1.0 and -2.5. For those who own a t score in this range that means your bone density is so low that only 16 percent of girls would have such a outcome.

As bone loss grows you might go from having osteopenia to osteoporosis. I feel the logic of the step is deeply flawed — to judge elderly girls by applying standards for young girls doesn’t make any sense. The scores are calculated by assessing how much a woman deviates in the bone density of a healthy young lady. That’s like using a 70 year old run a 100 yard dash against a 20 year old, and if he loses, stating that the elderly man has a disorder.

Bone density

It normally declines with age, and therefore there’s absolutely not any reason to think that this is necessarily a cause for concern. Yet today for those who have an abnormal BMD test, defined as a t score of greater than 2.5, the NOF guidelines include information to “talk to a doctor” and provide a description of drugs used to prevent fractures. For instance, if you’re a woman who receives BMD testing and follows the WHO criteria, then there’s a 50% chance you’ll be diagnosed with osteoporosis at age 72 (t score less than -2.5), and a fantastic chance your physician will recommend medication therapy. Your risk of getting osteopenia (t score less than -1.0), for which your physician may recommend medication to “stop” osteoporosis, is 50 percent by age 52. To put it differently, according to the guidelines, half of postmenopausal women should be taking medication for osteoporosis.

However, as I show in the next section, recommendations for a lot of women to take bone drugs do not make any sense. Also, even though BMD forecasts fracture, and drugs increase BMD, that does not mean they necessarily stop fracture (not those which cause loss of pain or function ). This is the older A equals B and B equals C therefore A equals C. Osteopenia causes fracture, and medication reduces osteopenia, therefore medication reduces fracture. Normally there are two types of cells which regulate bone regeneration, osteoblasts and osteoclasts. The osteoblasts are actively raising bone by laying down calcium and phosphate. Osteoclasts, consequently, are chewing bone up on the opposite end. In young people there’s a balance of both of these activities. When you get older, however, osteoblast activity declines, and thus your muscles get thinner.

Keep in mind

Popular osteoporosis drugs get in between the bone and the osteoclast and block the osteoclast from breaking down bone. This contributes to an increase in bone mineral density. But what doctors and drug manufacturers often don’t tell you is that the medications used to treat osteoporosis, which I discuss soon, raise the laying down of calcium on the outer, cortical bone, which is more densely packed. The bone, known as trabecular bone, is less dense, but creates a lattice like system which is more important for the strength of bone.

With aging there’s a loss of trabecular bone, therefore there is less area for calcium to be put down. Therefore calcium is preferentially laid back on the outer, cortical bone. This might improve your BMD score, but it will not automatically reduce your risk of fracture. And there are a number of especially nasty side effects to deal with, which I will discuss below.

The research studies do not show much benefit for women with no history of fracture, and any advantage goes away after a couple of years. According to that I say do not get your BMD checked, and exercise, stop smoking, and do other things to prevent fractures rather. If you’ve got a history of fracture it is possible to speak with your physician.

 

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