Men's Osteoporosis Support GroupSome research findings that "don't compute" There are several ideas we take for granted regarding osteoporosis: take more calcium and vitamin D to build strong bones, fractures occur due to low bone mineral density (BMD), and others. When I checked the recent literature this week, a few articles had results that didn't quite fit the norms, so I want to highlight them. Not so much looking at the overall research but concentrating on the findings that "don't compute." J Trauma. 2010 Apr 6. [Epub ahead of print]. Osteoporosis in Patients With a Low-Energy Fracture: 3 Years of Screening in an Osteoporosis Outpatient Clinic. Woltman K, den Hoed PT. PMID: 20375916. This is a study from The Netherlands showing some results of three years of screening in an osteoporosis outpatient clinic. Here are the interesting findings. #1. "The incidence of osteoporosis in patients with low-energy fractures is high, 46.4%." #2. "In patients diagnosed with osteoporosis, the hip fracture is the most common fracture site (34%), followed by the humerus (20.1%). Editor's comments. Regarding finding #1, what stands out to me is that 54.6% of the low-energy trauma fractures occurred in people who didn't have osteoporosis. That is, although we normally consider osteoporosis, equal to or less than -2.5 S.D. from normal BMD, as the major risk factor for low-trauma fracture, more fractures occurred in the non-osteoporosis group in this study. I don't have access to the full article so I can only conjecture as to the cause of this discrepancy. One thing that comes to mind is that falls might be even more important than low BMD. Should we be concentrating more on fall prevention than BMD? For item #2, what stood out to me was that 20.1% of fractures in those with osteoporosis occurred in the humerus. The two main fracture points that I recall reading about for osteoporosis are the hip and the wrist. I don't remember ever seeing the humerus mentioned. So add another bone to the list of those that often fracture due to osteoporosis: the humerus. BMC Womens Health. 2010 Apr 7;10(1):12. [Epub ahead of print].Association of physical exercise and calcium intake with bone mass measured by quantitative ultrasound. Dionyssiotis Y and others. PMID: 20374619. Free full text available here. This study used quantitative ultrasound (QUS) to measure heel BMD and correlated that with exercise and calcium intake in both pre-and postmenopausal women. Here's a statement from the free full text results section of the paper. "In contrast, postmenopausal women showed no difference in QUS T-scores regardless of the amount of daily calcium intake." The authors did find that for QUS T-scores, "Among systematically active premenopausal women who received more than 800 mg calcium per day, the difference was separately significant verses sedentary (p-0.028) and moderately active (p=0.04) women." The authors noted T-scores were also significantly higher compared to all other groups (meaning the postmenopausal women I presume). But since women lose BMD after menopause, that result is a given. So regarding BMD, as measured by QUS T-scores, there are two conflicting results. In premenopausal women, calcium intake of more than 800 mg/day AND more exercise were associated with higher scores. But, in postmenopausal women, calcium intake didn't affect QUS T-scores no matter what exercise group they were in. In the authors' conclusions, there is no mention of this discrepancy, they merely state, "Systematic physical activity and adequate dietary calcium intake are indicated for women as a means to maximize bone status benefits." Editor's comments. So we have the situation where, in premenopausal women, extra calcium and more exercise significantly increase BMD. Yet that effect, especially of the extra calcium, doesn't obtain in the postmenopausal women. Why is that? I didn't see a discussion of that in the article, so it appears to be something that just "doesn't compute." If high amounts of calcium are suggested for older, osteoporosis-prone individuals, you would expect to see a significant improvement in BMD for those taking more calcium. Int J Rheum Dis. 2009 Sep;12(3):225-9. Survey of vitamin D levels among post-menopausal Filipino women with osteoporosis. Raso AA and others. PMID: 20374350. This study of Filipino women with osteoporosis, mean age of 70 years, evaluated BMD and compared that to vitamin D status with the following as the definition of vitamin D status: "Serum 25-hydroxyvitamin D levels were divided as follows: 80-140 nmol/L (adequate), 25-79 nmol/L (inadequate/insufficient), and < 25 nmol/L (deficient)." The study found, "Fischer's exact test did not show a significant association between BMD and 25-hydroxyvitamin D (P = 0.4804)." The authors concluded, "These results suggest the possible contribution of factors other than vitamin D deficiency in post-menopausal Filipino women with osteoporosis." Editor's comments. These women all had osteoporosis, BMD at least -2.5 S.D. from the normal. Vitamin D is important for the absorption of calcium from the gut, and that is why it is monitored, to assure adequate serum calcium levels. If vitamin D is protective for osteoporosis, why did all these women have osteoporosis? Why wasn't there a difference in BMD between the groups with adequate vs. inadequate serum vitamin D levels? Additionally, 30% of them were taking calcium supplements that had vitamin D, so it might logically be concluded that 30% of the women had adequate intake of both calcium and vitamin D, yet there was no difference in the results for them either. The standard regimen for those taking one of the FDA-approved osteoporosis medications is to also give calcium/vitamin D supplements. I doubt that serum vitamin D levels are checked as a routine when osteoporosis is diagnosed, especially in postmenopausal women. Thus, 64% of the women in this study, were they to begin FDA-approved osteoporosis medications, would be told to take calcium and vitamin D supplements while their serum vitamin D level is already adequate. So this study in postmenopausal women gives confounding results that "don't compute." The take-home message I get is that you need to have your serum vitamin D levels tested as part of the osteoporosis work up after you have bone density testing done. If you test low, then get more sunshine or take supplements. But if your vitamin D levels are normal, there is no need for extra supplementation.
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