Osteoporosis

Bone is made up mostly of minerals such as calcium. The bones in our bodies are constantly being broken down and replaced with new bones. This bone-building cycle takes about 100 days and is influenced by the hormones produced in our bodies (such as estrogen in women) as well as by the levels of calcium and vitamin D. Osteoporosis occurs when bone tissue and minerals are lost faster than the bone is replaced.

There are two main types of osteoporosis: primary and secondary.

Primary osteoporosis occurs most commonly in women after menopause. Osteoporosis affects twice as many females over 70 years of age as males in the same age group.

Secondary osteoporosis can affect young and middle-aged people as well. It may be caused by:

• medications such as corticosteroids (e.g., prednisone*)
• chronic illnesses such as anorexia nervosa (an eating disorder that leads to malnutrition)
• too much exercise - women who exercise excessively may lose their menstrual cycle and the normal production of estrogen by the ovaries may stop

Factors that may increase the risk of osteoporosis include:

• drop in estrogen after menopause: The rate of bone loss increases significantly after menopause because the ovaries stop producing estrogen, a hormone that plays a major role in the bone repair process. Female athletes and women who suffer from anorexia nervosa may also be at increased risk for osteoporosis. In both cases, the menstrual cycle is disrupted or lost and levels of estrogen in the body drop dramatically. Women who experience early menopause (before 45 years of age) are more likely to have osteoporosis.  
• family history and body type: Osteoporosis tends to run in families, and the risk of this condition is greater for individuals with elderly relatives who have had a bone fracture, especially if it is a parent who has had a hip fracture. People of European and Asian descent are most at risk. People who are thin or "small-boned" also have a higher risk of osteoporosis. People who have had a fracture in the vertebrae are also at increased risk.  
• lifestyle factors and health conditions: Lifestyle factors such as smoking and excessive drinking, taking specific medications (such as corticosteroids), and having certain medical conditions (such as those that affect nutrition absorption [e.g., Crohn's disease, celiac disease], primary hyperparathyroidism, rheumatoid arthritis, and hypogonadism) may also contribute to bone loss. People with type 2 diabetes are more likely to suffer a hip or shoulder fracture than those without diabetes.  
• lack of exercise: Bones need to be used daily in order for them to stay healthy. People who are physically active are less at risk of developing osteoporosis, as their bones are stronger and less likely to lose strength with age. By contrast, a person who is bedridden or inactive for a lengthy period of time loses bone mass very quickly and is at high risk of osteoporosis.  
• lack of calcium: Children, adolescents, and adults need to eat the recommended amounts of vitamins and minerals. Calcium and vitamin D are very important in the maintenance of healthy and strong bones throughout life and in the prevention of osteoporosis.

Osteoporosis itself does not usually cause noticeable symptoms. However, weakened bones that are no longer able to support body weight can break even under slight pressure. Such fractures most commonly occur in the hipbones, wrists, or spine. Hip fractures are more frequent in people over the age of 75 years.

Some fractures caused by osteoporosis, such as hairline breaks in the spine, may cause little or no pain and may go unnoticed, even when they show up on an X-ray. By contrast, spinal crush fractures, where the vertebral column crumbles or collapses, are much more painful and can lead to deformed posture.

Another symptom caused by osteoporosis is chronic back pain. This pain can worsen even when you are making small movements such as regular activities around the house, or while coughing, laughing, or sneezing. You may even feel pain when you are standing still.

The key steps for diagnosing osteoporosis involve assessing your risk for fracture and evaluating your bone density.

If your doctor determines that you do have risk factors for fracture or osteoporosis (such as being 65 years or older or having had a fracture in the past), there are several effective and relatively quick tests that measure bone mineral density (BMD). If the results show that your bone density is too low, your doctor will likely diagnose you with osteoporosis.

Bone density measurement by a method called DEXA (dual energy X-ray absorptiometry) is the most effective way to assess osteoporosis risk. Scanning parts of the body such as the hips or spine using a special type of X-ray machine can confirm you have an increased risk of fractures. Computerized tomography (CT) scans can also be used to check the condition of the bones.

A heel ultrasound test may also be used to test bone density and estimate the risk of fracture for women over 65 years of age. However, heel ultrasound does not provide enough detail to monitor treatment for osteoporosis. If you have a heel ultrasound that detects low bone density, talk to your doctor about having your bone density tested by DEXA.

Following the diagnosis of osteoporosis, further studies are needed to look for possible causes. An examination to determine such causes might involve blood and urine tests to measure the levels of certain hormones produced in the body.

There are also two tools (CAROC and FRAX) available in Canada for your doctor to use to assess your 10-year absolute fracture risk. To determine your personal risk of fracture over the next 10 years, your doctor will take into consideration key risk factors which may include age, gender, body mass index, fracture history, family history, use of corticosteroids, smoking status, and alcohol intake.

If your doctor decides that you require medication to treat osteoporosis, BMD testing may be conducted every 1 to 3 years to see if the therapy is working. Once the medication is shown to be effective, you may not need to be tested as often. BMD testing may also be repeated to monitor for rapid bone loss in people who are not started on medications for osteoporosis but are at risk for developing the disease.

Treatment of osteoporosis is aimed at preventing or reducing bone fractures and maintaining or increasing bone density. There are several treatments for osteoporosis, but prevention is still very important. Many of the treatment and prevention strategies for osteoporosis are similar.

Maintenance of good bone strength requires that you have a regular intake of calcium. Osteoporosis Canada recommends 1,000 mg of elemental calcium daily for men and women between the ages of 19 and 50 years, and 1,200 mg for men and women over the age of 50 years. They recommend vitamin D in daily doses of 400 IU to 1,000 IU for adults without osteoporosis under 50 years of age, and 800 IU to 2,000 IU for both adults over the age of 50 and people with osteoporosis to help increase calcium absorption in the bones. Doses higher than 2,000 IU require medical supervision.

Osteoporosis Canada also recommends regular weight-bearing exercises and a healthy lifestyle with no smoking or excessive intake of alcohol.

Weight-bearing exercises (such as walking, weight training, or climbing stairs) play a role in strengthening bones and preventing fractures. Posture and balance can be improved through exercise and can significantly reduce the risk of bone fractures.

There are several medications that can be used to treat osteoporosis. Many of these treatments may also be used to prevent osteoporosis for people who are at high risk of developing it. The following are some of the osteoporosis medications available in Canada:

• bisphosphonates (e.g., alendronate, etidronate, risedronate, zoledronic acid): These are one of the main groups of medications that may be used to prevent and treat osteoporosis. These medications slow down bone loss and help repair bone, reducing the chance of fracture.
• selective estrogen receptor modulators (SERMs; e.g., raloxifene): These may also be used to prevent and treat osteoporosis in women.
• denosumab: Given as an injection, denosumab is part of a class of medications called RANK ligand inhibitors. It stops the breakdown of bone, helps to strengthen your bones and lowers the chances of fracture.
• testosterone: This is not recommended for the treatment of osteoporosis in most men. However, in some cases where osteoporosis in men is the result of hypogonadism, which is a condition of low levels of the male hormone testosterone, testosterone replacement therapy (androgen) may be used alone or with a bisphosphonate.
• hormone-replacement therapies (HRTs): A variety of HRTs are available for women who have reached menopause. Estrogen replacement helps to preserve bone and manage menopausal symptoms, but the therapy has a number of health risks. If you are taking or are considering taking HRT, talk to your doctor about the risks and benefits.
• parathyroid hormone analogues (e.g., teriparatide): This class of medication builds new bone faster than it breaks it down, and can be used to treat severe osteoporosis.

Two or more medications may also be used in combination to treat some cases of osteoporosis. In addition, doctors usually recommend that you continue to get enough calcium and vitamin D.

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