Osteoporosis is a bone disease where parts of the bone become weak and prone to fracture. This condition is more common in seniors, but can affect men and women of all ages. Osteoporosis is responsible for a large number of bone fractures that occur in seniors, as the weakened bones can no longer support their body weight.
About 10 million Americans have osteoporosis. While men also develop osteoporosis, this condition is particularly common among women who have reached menopause. The increased risk at menopause reflects the fact that the hormone estrogen, a key factor in maintaining bone strength in women, is no longer produced by the ovaries after menopause.
Because women have 30% less bone mass than men, women are particularly prone to osteoporosis as they age. However, by the age of 65 to 70 years, men and women lose bone at about the same rate. Eating enough food rich in calcium and vitamin D, and participating in weight-bearing exercise are important steps in preventing osteoporosis.
Bone is made up mostly of minerals such as calcium. The bone in our bodies is constantly being broken down and replaced with new bone. 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.
Bone density reaches a maximum around age 25 and then gradually declines thereafter. The decline is accelerated in women for 8 to 9 years after menopause, and then resumes a more gradual decline in bone density. Certain diseases and medications greatly increase calcium loss from bone.
Osteoporosis, a disease of bone already formed, is a different disease from osteomalacia, which is a disease of bone formation, and from osteoarthritis, which is an arthritic change in joints. Because of the similarity of names, these three separate conditions are often confused.
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 the age of 70 years 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 (a self-inflicted lack of food that leads to malnutrition) and celiac disease
- too much exercise - women who exercise excessively may lose their menstrual cycle and stop the normal production of estrogen by the ovaries
Factors that may increase the risk of osteoporosis include:
A 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 the age of 45 years) are more likely to have osteoporosis.
Family history and body type. Osteoporosis tends to run in families and the risk of this condition may be greater for individuals with elderly relatives who have had more than one bone 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, or who have first-degree relatives with hip fractures later in life, 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, 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 or vitamin D. 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. Recent attention to vitamin D has revealed that a large percentage of people today are deficient in vitamin D and aren't even aware of it.