osteoporosis

What is osteoporosis?

Osteoporosis is a condition characterized by the loss of the normal density of bone, resulting in fragile bone. Osteoporosis leads to literally abnormally porous bone that is more compressible like a sponge, than dense like a brick. This disorder of the skeleton weakens the bone causing an increase in the risk for breaking bones (bone fracture).

Normal bone is composed of protein, collagen, and calcium all of which give bone its strength. Bones that are affected by osteoporosis can break (fracture) with relatively minor injury that normally would not cause a bone fracture. The fracture can be either in the form of cracking (as in a hip fracture), or collapsing (as in a compression fracture of the vertebrae of the spine). The spine, hips, and wrists are common areas of bone fractures from osteoporosis, although osteoporosis-related fractures can also occur in almost any skeletal bone.

What are the symptoms of osteoporosis?

The osteoporosis condition can be present without any symptoms for decades, because osteoporosis doesn't cause symptoms unless bone fractures. Some osteoporosis fractures may escape detection until years later. Therefore, patients may not be aware of their osteoporosis until they suffer a painful fracture. Then the symptoms are related to the location of the fractures.

Fractures of the spine (vertebra) can cause severe "band-like" pain that radiates around from the back to the side of the body. Over the years, repeated spine fractures can cause chronic lower back pain as well as loss of height or curving of the spine, which gives the individual a hunched-back appearance of the upper back, often called a "dowager hump."

A fracture that occurs during the course of normal activity is called a minimal trauma fracture or stress fracture. For example, some patients with osteoporosis develop stress fractures of the feet while walking or stepping off a curb.

Hip fractures typically occur as a result of a fall. With osteoporosis, hip fractures can occur as a result of trivial accidents. Hip fractures may also be difficult to heal after surgical repair because of poor bone quality.

What factors determine bone strength?

Bone mass (bone density) is the amount of bone present in the skeletal structure. Generally, the higher the bone density is, the stronger are the bones. Bone density is greatly influenced by genetic factors, which in turn are sometimes modified by environmental factors and medications. For example, men have a higher bone density than women. African Americans have a higher bone density than Caucasian or Asian Americans.

Normally, bone density accumulates during childhood and reaches a peak by around age 25. Bone density is then maintained for about ten years. After age 35, both men and women will normally lose 0.3% to 0.5% of their bone density per year as part of the aging process.

Estrogen is important in maintaining bone density in women. When estrogen levels drop after menopause, bone loss accelerates. During the first five to ten years after menopause, women can suffer up to two to four percent loss of bone density per year! This can result in the loss of up to 25 to 30% of their bone density during that time period. Accelerated bone loss after menopause is a major cause of osteoporosis in women.

What are the risk factors for developing osteoporosis?

Factors that will increase the risk of developing osteoporosis are:

• Female gender;

• Caucasian or Asian race;

• Thin and small body frames;

• Family history of osteoporosis (for example, having a mother with an osteoporotic hip fracture doubles your risk of hip fracture);

• Personal history of fracture as an adult;

• Cigarette smoking;

• Excessive alcohol consumption;

• Lack of exercise;

• Diet low in calcium;

• Poor nutrition and poor general health;

• Malabsorption (nutrients are not properly absorbed from the gastrointestinal system) from conditions such as celiac sprue;

• Low estrogen levels (such as occur in menopause or with early surgical removal of both ovaries);

• Chemotherapy can cause early menopause due to its toxic effects on the ovaries;

• Amenorrhea (loss of the menstrual period) in young women also causes low estrogen and osteoporosis; Amenorrhea can occur in women who undergo extremely vigorous training and in women with very low body fat (example: anorexia nervosa);

• Chronic inflammation, due to diseases (such as rheumatoid arthritis and chronic liver diseases);

• Immobility, such as after a stroke, or from any condition that interferes with walking;

• Hyperthyroidism, a condition wherein too much thyroid hormone is produced by the thyroid gland (as in Grave's disease) or is caused by taking too much thyroid hormone medication;

• Hyperparathyroidism, a disease wherein there is excessive parathyroid hormone production by the parathyroid gland (a small gland located near the thyroid gland). Normally, the parathyroid hormone maintains blood calcium levels by, in part, removing calcium from the bone. In untreated hyperparathyroidism, excessive parathyroid hormone causes too much calcium to be removed from the bone, which can lead to osteoporosis;

• Vitamin D deficiency. Vitamin D helps the body absorb calcium. When vitamin D is lacking, the body cannot absorb adequate amounts of calcium to prevent osteoporosis. Vitamin D deficiency can result from lack of intestinal absorption of the vitamin such as occurs in celiac sprue and primary biliary cirrhosis;

• Certain medications can cause osteoporosis. These include long-term use of heparin (a blood thinner), anti-seizure medications phenytoin (Dilantin) and phenobarbital, and long term use of oral corticosteroids (such as Prednisone).

How is osteoporosis treated and prevented?

The goal of osteoporosis treatment is the prevention of bone fractures by stopping bone loss and by increasing bone density and strength. Although early detection and timely treatment of osteoporosis can substantially decrease the risk of future fracture, none of the available treatments for osteoporosis are complete cures. In other words, it is difficult to completely rebuild bone that has been weakened by osteoporosis. Therefore, prevention of osteoporosis is as important as treatment. Osteoporosis treatment and prevention measures are:

1. Life style changes including quitting cigarette smoking, curtailing alcohol intake, exercising regularly, and consuming a balanced diet with adequate calcium and vitamin D;
   
   
2. Medications that stop bone loss and increase bone strength, such as alendronate (Fosamax), risedronate (Actonel), raloxifene (Evista), ibandronate (Boniva), calcitonin (Calcimar), and zoledronate (Reclast);
   
   
3. Medications that increase bone formation such as teriparatide (Forteo).

Lifestyle changes

Exercise, quitting cigarettes, and curtailing alcohol

Exercise has a wide variety of beneficial health effects. However, exercise does not bring about substantial increases in bone density. The benefit of exercise for osteoporosis has mostly to do with decreasing the risk of falls, probably because balance is improved and/or muscle strength is increased. Research has not yet determined what type of exercise is best for osteoporosis or for how long. Until research has answered these questions, most doctors recommend weight-bearing exercise, such as walking, preferably daily.

A word of caution about exercise: it is important to avoid exercises that can injure already weakened bones. In patients over 40 and those with heart disease, obesity, diabetes mellitus, and high blood pressure, exercise should be prescribed and monitored by their doctors. Finally, extreme levels of exercise (such as marathon running) may not be healthy for the bones. Marathon running in young women that leads to weight loss and loss of menstrual periods can actually cause osteoporosis.

Smoking one pack of cigarettes per day throughout adult life can itself lead to loss of 5% to 10% of bone mass. Smoking cigarettes decreases estrogen levels and can lead to bone loss in women before menopause. Smoking cigarettes can also lead to earlier menopause. In postmenopausal women, smoking is linked with increased risk of osteoporosis. Data on the effect of regular consumption of alcohol and caffeine on osteoporosis is not as clear as with exercise and cigarettes. In fact, research regarding alcohol and caffeine as risk factors for osteoporosis shows widely varying results, and is controversial. Certainly, these effects are not as powerful as other factors. Nevertheless, moderation of both alcohol and caffeine is prudent.