Saturday, December 31, 2011

A BMD conspiracy?

A few weeks ago, I received updated bone density results. It's been a year since I was first diagnosed with low bone density. At the end of 2010, my doctor gave me a choice of going on bisphosphonates (like Boniva) or increasing my weight bearing activity. I had heard scary things about this class of drugs, and I'm always leery of putting any kind of pill down my throat, so I chose the natural route. I began running.

Running utterly sucked at first. Two miles at 9+ minute pace destroyed my hips. I thought surely I'd do 20 years damage in two weeks taking up this abusive activity going on 50 years of age. But two miles became three, 9 minute pace became 8, and excruciating discomfort subsided.

Towards the middle of this year, I actually began looking forward to some of my runs. I learned it was a very efficient way to get my fix. Just sneakers and shorts were needed. Especially on wet days, there was no messy bike to deal with later. I didn't run a lot, typically around an hour per week. This was enough to net me a sub-6 minute pace 5k at the CIGNA race in August. That will probably be one of my top 2011 athletic highlights.

Surely all this pounding was beefing up my bones. I could feel it. It has been years, decades even, since I felt so solid on my feet. Amazingly, my titanium reinforced ankle had absolutely no qualms about running. I began counting down the days to my first follow-up DEXA bone density scan. I wanted confirmation I was doing something positive for my body. I suspect running diluted or degraded the quality of my bike workouts this summer, partially to blame for mediocre results on the bike. I felt diminished performance on the bike was a fair trade for improved bone health and higher level of overall fitness.

When I received the results, I was a bit dismayed. I did not expect mixed results. I'm still trying to get my head around this. The DEXA scan measures three points, your spine and each hip. Let's start with the spine. My spine bone mineral density (BMD) went down 1.5%.  I was 1.018g/cm3 on Dec 12, 2010, and now 1.003g/cm3 on Nov 11, 2011. This drove my T-score down from -1.8 to -1.9. A T-score below -2.0 is considered high risk of fracture, and below -1.0 in osteopenia range. This is disconcerting, as two cyclists I know have fractured their spines in 2011.

My right hip was essentially unchanged. BMD went up 0.7%, which is within the measurement error of a DEXA scan. My T-score stayed the same at -1.5, which isn't horrible, but I'd like to see this back into the normal range above -1.0.

The only good news that came out of this was my left hip. Left hip BMD was very low last year, most likely a result of being in a cast most of the summer. Bone atrophies just like muscle does. I suspect even if I did nothing special this past year, left hip BMD would have bounced back some. The DEXA scan shows a 5.3% improvement from last year, raising my T-score from -2.1 to -1.8. I'd like to say running did this, but then why didn't my right hip improve?

So all three measured areas are still at moderate risk of fracture and in the osteopenia range of -1.0 to -2.5. A T-score below -2.5 is osteoporosis. My spine is closer to osteoporosis than normal. I thought it odd my doctor didn't think this warranted concern or further action. In fact, he said things looked good and results were normal. I will probably seek a second opinion on this. My mother's BMD wasn't even as low as mine, and she was put on Fosamax. I engage in far more riskier activities than she does.

So where do I go from here? I do question my diet. I suspect my diet has a decidedly acidifying effect on my body. This can make calcium retention challenging. I also enjoy strong coffee, and caffeine can interfere with calcium absorption. I plan to increase my supplemental calcium to 1200mg per day (not a crazy amount) and add 2000 IU of vitamin D in the winter months. I get tons of calcium in real food in my diet, but if I have trouble absorbing it, increased supplemental intake might help. In summer months, I get enough sunlight exposure that I do not need to take a D supplement.

I will continue running. As long as I experience no ill effects from it, running will maintain balance in my body that  just cycling could never bring. There's more to bones that just BMD scores measured by some machine too.

There are groups out there crying foul, generally groups that are skeptical of all modern medicine techniques. You see, a Dual Energy X-ray Absorptiometry (DEXA) machine measures a particular physical trait of our bones. Drug companies have discovered that a certain class of drugs can quite effectively modify this trait, namely BMD. The assumption is that higher BMD is always better. After all, women with osteoporosis have very low BMD, and there is high correlation between low BMD and fracture rates. So is the converse true, that high BMD is correlated with low rate of fractures? The answer now appears to be not always.

You see, when a person goes on a bisphosphonate for many years, they will experience a significant boost in BMD. Studies show a sharp drop in fractures when first going on these drugs. However, these drugs have been on the market a long time now, and a few women that have been on them for more than 5yrs are experiencing freak fractures. Grotesque fractures. Femurs that shatter into pieces for no reason at all, and then the fracture doesn't heal well. For years in some cases.

Apparently, bisphosphonates can stay in the body for decades, so when you stop taking them, their effects can linger for a very, very long time. Bisphosphonates halt bone mineral turn-over, and thus repair of micro-fractures. When micro-fracture repair is halted, over a period of many years, a bone can become filled with fractures lines until one day the bone shatters like glass. Without warning. Yet a BMD scan would show all is well.

So pundits charge it is a scam. A machine is invented that finds a problem, then a drug is sold to fix said problem, when in fact, a high BMD score does not necessarily mean a strong bone. I generally don't subscribe to conspiracy theories and don't believe one exists here. I do believe money is to be made, as half of our population is female, and most females will develop osteoporosis late in life. New guidelines are now prescribing that women go off these drugs for periods of time to let bones self-repair.

I certainly want to avoid bisphosphonates. The big question on my mind these days is this. Are my bones stronger now than they were one year ago even though my BMD score stayed the same? I would think over 400 miles of pounding on pavement has had some impact. I certainly feel more stable on my feet, and I feel at lower risk of injury in other ways due to running. I'll keep running in 2012. I will go another year to see if some real improvement can be obtained. Since my doctor said I was "normal," I don't have another follow-up DEXA scan planned. I will have to discuss this with him, and if he still believes there is nothing to worry about, I'll seek another opinion.

Thanks for reading, and Happy New Year!


Mathias said...

Did you drop more weight this year due to the increased running?

Hill Junkie said...

Yes, I've averaged 3-5 lbs less weight this summer than any summer since I've taken up cycling. Running seems to tone your whole body up. It also seems to me that a 30 minute run spikes the metabolism the same as a hard one hour ride.

Alby King said...

Really appreciate your scientific evaluation with stuff like this.

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