Osteoporosis

"Osteo" means bone, and "porosis" means thinning, so osteoporosis literally means thinning of the bone. It is a disease where the insides of the bones grow porous and thus are fragile and prone to fracture. It affects more than 800,000 Canadians; that's 1 in 37 Canadians. Symptoms Many people have osteoporosis and don't know it. That's because this is a disease without symptoms - until a bone fractures. Typically the fractures occur in the femur (bone in the thigh), the hip, or the distal radius (the lower arm above the wrist), during what seems like a minor fall. Sometimes people with osteoporosis develop just a hairline break in a spinal vertebra that causes little or no pain. Sometimes the vertebral column crumbles or collapses, and then there's a lot of pain. As vertebrae collapse, the person loses height or may develop a stooped posture. Other signs include back pain from laughing, coughing, or sneezing - even just standing still.

Cause

Osteoporosis is caused by a significant loss of bone mass. To understand how people lose bone mass it's important to know that bone is living tissue; new bone is constantly replacing old bone. Two kinds of cells are responsible for the work; one triggers bone breakdown and resorption (osteoclasts), the other (osteoblasts) builds it up. Up until the age of 30, the osteoblasts are the busiest ones, creating a scaffolding of protein and then filling in the spaces with calcium and other minerals such as phosphorus. This "modelling" of the bones supports our skeleton where most of the outside force occurs: the spine, the hips, the hands, etc. Hormones such as estrogen and testosterone guide the process.

Our bone mass reaches its peak around the time we reach 30 and for a while the osteoblasts and osteoclasts work at the same pace. Then, around the age of 50 or so, as the body produces less hormones, the work of the osteoclasts outpaces that of the osteoblasts, and bone is resolved faster than it's created, causing the density of the bone to decrease.

For many people this gradual decrease in bone density isn't a problem, but for others the decrease is dramatic and eventually the bones become so porous and fragile that they can break very easily. This is called primary osteoporosis and it is most common in women aged 50 to 65 years, who've been through menopause (with the consequent cessation of hormone production). Women are 4 times more likely to develop osteoporosis than men.
There's another kind of osteoporosis, called secondary osteoporosis, which generally affects young and middle-aged people. The calcium loss is usually caused by one of the following:

• medications such as corticosteroids (e.g., prednisone);
• excessive physical training (which sometimes causes a woman's periods to cease and her ovaries to stop producing estrogen);
• malnutrition, such as that caused by anorexia nervosa (a self-imposed starvation).

Risk factors

Some people are more likely to develop osteoporosis. Being female, getting older, and being inactive top the list of risk factors. Other factors include:

• family history: having a family member with osteoporosis;
• physique: being thin and/or having a small frame;
• diet: one lacking foods that contain sufficient vitamin D, calcium, and phosphorus, one that includes too much alcohol, caffeine, and certain sodas;
• smoking;
• race: being Caucasian or Asian.

Diagnosis

Bone density scans are a surefire way of telling whether you have osteoporosis. A scan can detect the bone loss before a fracture occurs, it can predict your chances of fracturing in the future, and, if conducted yearly, it can determine your rate of bone loss as well as monitor the effects of treatment.

For women at risk, many doctors advise them to have a bone density scan even before menopause (in order to have a baseline for later comparison), and then yearly, for the few years after menopause when bone loss may be occurring fastest. (Many women lose from 3 to 5 percent of their bone mass a year during the first 5 or 6 years following menopause).

While it is difficult to identify who will develop osteoporosis based on the risk factors listed above, the absence of these factors are useful for spotting who is not likely to develop the disease - and therefore who probably won't require a bone density scan.

Treatment

There is no cure for osteoporosis. There are nonetheless effective treatments that can slow down and even reverse bone mass loss. If you develop osteoporosis, there are a variety of medications for your doctor to choose from, depending on your personal history. Possible medications include one of the bisphosphonates (e.g., Fosamax®, Actonel®) and calcitonin (e.g., Miacalcin®). For women, estrogens (e.g., Premarin®, Ogen®) and raloxifene (e.g., Evista®) can also be used. In addition, your doctor will likely recommend a calcium supplement (with between 1000 and 1500 mg elemental calcium and between 800 and 1000 IU of vitamin D a day, depending on your age) and an exercise program. Expect to have to take the medications long term and have repeated bone density scans so your doctor can track the treatment and modify your medications, if necessary.

Prevention

Developing strong bones during childhood and adolescence is the best way to prevent weak bones later on. By about 20 years old, we have acquired most of our skeletal mass. As an adult, we can keep our bones in the good health by:

• getting our daily recommended amounts of calcium and vitamin D, through food or daily supplements;
• engaging in regular weight-bearing exercise;
• avoiding smoking and excessive alcohol.

For more information or for support :

Osteoporosis Society of Canada

www.osteoporosis.ca