World Osteoporosis Day
The first two years of medical school, during which medical students are inundated with floods of information on all the various ways in which someone’s health can go awry, are enough to turn even the most stoic logician into a veritable hypochondriac.
For me, and I daresay for many of my 20-some year-old classmates, perhaps the most worrisome information came close to the end of our classroom-based curriculum. After 10 or so months drilling into our heads all possible maladies of the heart, circulatory system, respiratory system, digestive tract, urinary tract, reproductive tract, skin, and brain, we had just launched into our rheumatology unit when our professors informed us that we had only until age 30 to build up our peak bone density. After this, we would spend the rest of our lives gradually losing bone density — perhaps descending into osteoporosis, and all of its debilitating sequelae, if we didn’t start our descent from a high enough “altitude.”
And the way to climb higher on the bone density mountain? Physical activity.
My classmates shifted uneasily in their seats. Although there were a few devoted exercise enthusiasts among us, everyone else was suddenly painfully aware of the hours and hours they spent glued to a seat: listening to lectures, studying their notes, doing practice questions for the first installment of our board exams, or — for the somewhat less studious — playing video games.
Our demanding schedule provided many convenient excuses to avoid hitting the gym. Although as aspiring physicians we all knew the value of regular exercise to overall good health, its connection to the prevention of other illnesses — cancer, heart disease, depression — was vague and distant enough to let the excuses prevail. But now we were presented with an all-too-direct threat to our health and an all-too-actionable preventative measure, one that couldn’t be put off for later as we all inched (or rather hurtled) ever closer to the “30” cutoff.
Although I can’t attest to the actions of my classmates, I, for one, was duly guilted into recruiting a friend — one of the aforementioned exercise enthusiasts — to help me create a five-day-a-week exercise schedule, complete with cardio and strength training. In an admirable showing for someone as exercise-averse as me, I managed to stick to this schedule for the entire two weeks that remained in the semester before the uneasy fear instilled in me by our rheumatology professors was eclipsed by the more immediate fear of failing my board exam, allowing me to swap my exercise schedule for a much more intensive study schedule.
More than five years later (yes, I am still in school—M.D.–Ph.D. students have a long road to travel), I have so far been unable to recapture that fervent motivation even though “30” is now just around the corner. But occasionally a creeping anxiety still passes through my still-salvageable bones when I remember that the bone density clock is ticking, because osteoporosis — a disease significant enough in prevalence and individual impact to merit its own awareness day each year on Oct. 20 — is not to be taken lightly.
Here, I’ll take a closer look at what osteoporosis entails before digging into some recent research articles on the subject. With any luck, it will be enough to push me — and maybe some of you — into an exercise routine that will help us reach the peak of the bone density mountain before we begin our inevitable descent. And for those readers past 30, you’re not completely off the hook:
What is osteoporosis, and what symptoms does it cause?
Although we often think of bone as a static support system for the rest of our organs and tissues, it is actually composed of dynamic, living tissue. The majority of bone volume is occupied by a strong matrix of organic collagen fibers (along with a few other proteins) interspersed with inorganic calcium and phosphate crystals (mostly in a form called hydroxyapatite), which harden the matrix. Nestled within this matrix are cells — mainly osteoblasts and osteoclasts — that continuously remodel bone tissue by respectively laying down new and breaking down existing matrix.
The balance of these two activities — bone formation and resorption — determines bone growth and density and shifts naturally over a person’s lifespan (as shown the figure). Children and teenagers enjoy a brisk pace of osteoblast activity that eclipses osteoclast activity enough to cause lengthening at still-open growth plates on long bones in addition to densifying of bone. Young adults up until about age 30 continue to benefit from a balance tipped in favor of bone formation, resulting in continued densifying of bone. After this period, bone resorption accelerates, outstripping formation and leading to gradual loss of bone density and therefore weakening of bones.
If bone density drops too low, the weakened bones become susceptible to fractures from even mild impacts. Such “fragility fractures” are the main consequence of osteoporosis. Further sequelae can result from these fractures and impact quality of life: fractures in long bones and hips can impair motility (with the latter often requiring risky, sometimes fatal surgery), wrist fractures can hinder use of the hands, rib fractures can cause pain with each breath as they heal, and vertebral fractures can elicit chronic pain and bend the back into a permanently stooped posture.
from osteoporosis patients of many walks of life and from many different cultural backgrounds provides a more intimate look at the deleterious impacts osteoporosis can have on everyday life.
Osteoporosis is often not diagnosed until a usually elderly individual suffers a tell-tale fracture, often from a fall. However, bone mineral density (BMD) can be measured in the clinic, a screening measure currently , by means of dual energy X-ray absorptiometry (DEXA). DEXA measures the absorption of two X-ray beams of different energy levels by the bones, usually those of the lumbar spine and hip but sometimes substituting the forearm if one or both are inaccessible, in order to calculate BMD. For post-menopausal women and men over age 50, results are compared to standard data for healthy