THE VIEW FROM THE OFFICE
OSTEOPOROSIS: WHAT WE DON'T KNOW IS A LOT MORE THAN WHAT WE KNOW
The primary predictive risk factor for osteoporosis is how old you are. One simple preventive, therefore, is not to grow old. If we're not interested in this strategy, what do we do?
The most effective preventive strategy is to keep active and eat a good diet throughout life. Live a healthy lifestyle and generally you don't have to worry about problems like this. [See healthy lifestyle formula below.]
Smoking directly reduces bone strength and mineralization. 5 servings of brightly and multi-colored fruits and vegetables a day give you lots of extra calcium. Having a high body mass index actually protects you from osteoporosis, but leads to such an unpleasant assortment of other problems, it is not worth it. Exercise is absolutely essential both for a healthy life and for the prevention of osteoporosis. If you do all 5 steps of a healthy lifestyle, then you won't need to worry about osteoporosis when you're older. You just keep doing what you're doing.
Well, you're older now, and you may not have done all that lifestyle stuff as regularly as you would have wished. What now? The current national recommendation from the US Preventive Services Task Force (USPSTF) is to a risk assessment for osteoporosis at age 65 for women. There is insufficient evidence yet to recommend such screening for men. There are multiple ways of doing this. Getting a DEXA bone scan for bone density is the most popular (and the most lucrative for those who run the machines), but it is not the only way. I actually prefer something called the "Osteoporosis Risk Assessment Instrument"; you only have to answer 3 questions to calculate your risk. [Click on this link, Osteoporosis Risk Assessment Instrument,to calculate your own risk. You get 9 points if your age is between 64 to 74, and 15 points if your age is 75 or older; you also get 9 points if your weight is less than 60 kilograms or 132 pounds.]
Now the website will say, if your score is 9 or greater, you should get a DEXA scan. I say, if your score is 9 or greater, then you should proceed to some reasonable treatment for osteoporosis. If you end up taking calcium, vitamin D, and getting more weight-bearing exercise and you don't have osteoporosis, you have really done yourself no harm. If you do have osteoporosis, then you're doing the right thing. I don't really see what the DEXA scan gets you other than the illusion that you know what's going on and what to do about it. The DEXA scan itself is not the criteria to use to decide whether to take a medicine like Fosamax. The occurrence of a fracture is the definitive criteria for that decision. Many will argue that it seems better to take the Fosamax before you get a fracture, and this is a perfectly reasonable leap of faith, but you will be acting beyond the limits of our current knowledge.
Anyway, in my view the simple Osteoporosis Risk Assessment Instrument is a much, much simpler way of seeing if you should get serious about your risk of osteoporosis. It is also a great deal cheaper than a DEXA scan. As you can see the major risk is age, followed by weight, and the third factor is whether you take estrogens for menopausal symptoms, which relatively few women do anymore.
So, if you do have a high risk score, what you do you do about it. The primary treatment is--guess what? Exercise, calcium, and vitamin D. No secret here. The recommended amount of exercise is 22 minutes of weight-bearing activity (walking does fine) a day, 1000 mg of calcium a day, and at least 800 IU of vitamin D. The special medications (the most common one being Fosamax (alendronate) are not indicated unless you have already had a fracture from osteoporosis.
Some practical tips:
1. A DEXA bone scan is not the only way to assess risk. A simple 3 question score (Osteoporosis Risk Assessment Instrument) will do the job more easily. Try it.
2. There is no evidence that repeating a bone scan leads to any clinical benefit. The proven value of the test is a one-time thing only--it confirms that you have osteoporosis. It is clear from the studies that repeating the scan in less than 2 years leads to inaccurate results--either false reassurance or unnecessary worry. If the DEXA scan gets worse after 2 years, there's not much else to do. Just exercise, calcium, vitamin D, and Fosamax (or other bisphosphonate).
3. Drugs for osteoporosis still have several controversial aspects.
a. They are clearly beneficial only for patients who have had prior fractures. In this case, they definitely reduce the rate of subsequent fractures.
b. We do not have any proven evidence of benefit from receiving treatment for more than 5 years. The studies haven't been performed for longer than this. There is some evidence of harm from prolonged treatment--primarily increased brittleness of the bones and a possible risk of a relatively rare complication, osteonecrosis of the jaw bone. It is quite reasonable just to stop this medication after 5 years of use; you have received most, if not all, of the benefit.
4. The amount of calcium that is recommended is 800 to 1500 mg per day. You can get this in a single supplement tablet, but you can also get it naturally. The dark green leafy vegetables like kale have lots of calcium. One cup of kale is equivalent to a cup of whole milk in calcium content--about 400 mg.
5. Vitamin D is the subject of increasing controversy. In recent years it has been learned that higher levels of vitamin D in the blood are associated with a reduced risk of heart disease and cancer, not just osteoporosis. What is not clear is whether giving a vitamin D supplement, of 800 to 2000 IU a day makes a difference. There are no studies confirming this, but it is widely expected to be helpful based on the basic science of human vitamin D metabolism. There are, of course, other ways to get vitamin D, of which regular exposure to sunlight is the best. You only need 10-15 minutes a day and not every day.
What is becoming clear is that around the world large numbers of people are deficient in vitamin D. In my last practice at Kaiser, I was routinely testing for vitamin D in all of my patients and found that about 20% of them were significantly deficient as the Kaiser laboratory defined the test (below 30 pcg/mL was considered deficient). What was really surprising is that a number of patients who were deficient were younger, had good diets, and exercised regularly. So what gives? A recent Institute of Medicine report suggests that we don't need to worry until the level is less than 20. Another problem, however, is that there is considerable variation from lab to lab in the way vitamin D levels are measured and reported. So what is considered deficient in one laboratory may be considered adequate in another.
There is enough controversy and uncertainty about the efficacy of routine screening for serum vitamin D levels that I no longer endorse it. What I do endorse, however, is routine supplementation for everyone with a multivitamin containing vitamin D, at least 800 IU per day for the average adult.
6. Not all exercise is considered exercise from the perspective of preventing osteoporosis. This rather strange conclusion was brought to my attention by a patient in my practice here in Graeagle. He is a regular bicycle rider. He had heard that, since bicycle riding is not strictly weight-bearing, that it was ineffective in preventing osteoporosis, and he requested a DEXA bone scan for himself. I ordered it for him, expecting it to be fine, but it turns out he was right. He had osteoporosis. I did a search through the literature and found a number of well-substantiated reports confirming that intense bicycle riding does not prevent osteoporosis. A similar problem may present itself to vigorous swimmers as well. The results suggest, in fact, that the more intense the bike riding, the greater the risk of osteoporosis (at least on the bone scan). Another factor that may be adding to the problem is that sweat contains a substantial amount of calcium; the more you sweat, the more you lose. You can lose up to 20 mg of calcium per hour through heavy sweating. Some clinical studies suggest that this effect is significant.
Of course, my patient has never had a fracture and may never get one. He does not want to take the Fosamax medication, and it is not clear that he should. So he is left with going back to calcium (which he prefers to do through natural diet), vitamin D, and exercise. He should add some regular walking to his bike riding.
Who would have thought that a healthy person who is an avid bike-rider would need to worry about osteoporosis? We're still not really sure what all this means. It is not clear that he has any disease. It is clear that his bones look thinner than average on a DEXA scan. The real test of whether he has a disease or not is whether he experiences any clinical problem, and this has not happened yet. So we wait and see. The big question is what does he or you do in the meantime, while you're waiting. That's a personal decision.