What is Osteoporosis?

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Osteoporosis, which means "porous bones," causes bones to become weak and brittle - so brittle that even mild stresses like bending over, lifting a vacuum or coughing can cause a fracture. In most cases, bones weaken when you have low levels of calcium, phosphorous and other minerals in your bones. Osteoporosis also can accompany endocrine disorders or can result from excessive use of drugs such as corticosteroids.

The good news about osteoporosis is that it's never too late to do something about it. If you are a woman and haven't reached menopause, you can take measures to prevent osteoporosis from silently draining your bones of strength. And if you're past menopause, tests can detect the early stages of the disease and halt the bone drain before debilitating fractures rob you of your mobility and independence.

The causes of osteoporosis

The strength of your bones depends on their mass and density. And bone density depends in part on the amount of calcium, phosphorus and other minerals bones contain. When your bones contain fewer minerals, their strength is decreased and they lose their internal supporting structure.

Scientists have yet to learn all the reasons this occurs, but the process involves how bone is made. Bone is continuously changing - new bone is made and old bone is broken down, a process called remodelling, or bone turnover.

A full cycle of bone remodelling takes about 2 to 3 months. When you're young, your body makes new bone faster than it breaks down old bone, and your bone mass increases. You reach your peak bone mass in your mid-30s. After that, bone remodelling continues. But you lose slightly more than you gain - about 0.3 percent to 0.5 percent a year. Not getting enough vitamin D and calcium in your diet can accelerate the process.

When you go through menapause, oestrogen levels drop and bone loss accelerates to about 1 percent to 3 percent a year. Around age 60, bone loss slows but doesn't stop. As women reach older ages, they may have lost between 35 percent and 50 percent of their bone mass. Men may have lost 20 percent to 35 percent.

Your risk of developing osteoporosis depends on how much bone mass you attained between ages 25 and 35 (peak bone mass) and how rapidly you lose it later. The higher your peak bone mass, the more bone you have "in the bank" and the less likely you'll be to develop osteoporosis as you lose bone during normal aging. Getting enough calcium and vitamin D in your diet, which is essential for absorbing calcium, and exercising regularly can help ensure that your bones stay strong throughout your life.

Early detection is important in osteoporosis. You may be able to slow the disease if you find out you have it or prevent it if you discover you're likely to develop it. Consider the following risk factors, then discuss your risk with your doctor and plan your prevention strategy. If you're a woman, it's best to do this well before menopause. Risk factors include:

• Gender. Fractures from osteoporosis are about twice as common in women as in men. That's because women start out with lower bone mass and tend to live longer. They also experience a sudden drop in oestrogen at menopause that accelerates bone loss. Slender, small-framed women are particularly at risk. Men who have low levels of the male hormone testosterone are also at increased risk.
• Age. The older you get, the higher your risk for osteoporosis. As men live longer, their risk also increases.
• Race. You're at greatest risk for osteoporosis if you're white or of Southeast Asian descent. Blacks have the lowest risk, and Hispanics and American Indians appear to have an intermediate risk.
• Family history. Having a mother or a sister with osteoporosis increases your risk.
• Tobacco use. The exact role tobacco plays in osteoporosis isn't clearly understood, but researchers do know that tobacco use contributes to weak bones.
• Lifetime exposure to oestrogen. The greater your lifetime exposure to oestrogen, the lower your risk of osteoporosis. For example, you have a lower risk if you have a late menopause or you began menstruating at an earlier than average age. But if you have a history of abnormal menstrual periods, experience menopause earlier than your late 40s or have your ovaries surgically removed before age 45 without receiving hormone replacement therapy (HRT), your risk is increased.
• Chronic alcoholism. For men, alcoholism is one of the highest risk factors for osteoporosis. Excess consumption of alcohol reduces bone formation and interferes with your body's ability to absorb calcium.

Here are some facts about osteoporosis

• 1 in 3 women and at least 1 in 12 men will develop osteoporosis during their lifetime
• Every 3 minutes someone has a fracture as a result of osteoporosis
• World-wide there was an estimated 1.66 million hip fractures in 1990 and it is estimated that this will rise to 6.26 million in 2050
• Each year the numbers of people with osteoporosis seen by doctors include over:
  70,000 hip fractures
  50,000 wrist fractures
  40,000 spinal fractures
• Once a postmenopausal woman has had one spinal fracture, she is 5 times more likely to suffer another
• Only a third of people with spinal fractures caused by osteoporosis come to medical attention