|
|||||||||||||||||||||||||||||||||
|
|||||||||||||||||||||||||||||||||
 |
|||||||||||||||||||||||||||||||||
|
Osteoporosis DEFINITION O steoporosis is Greek for “porous bone,” and a disease characterized by low bone mass and structural deterioration of bone tissue leading to bone fragility and increased susceptibility to fractures. These fractures occur most commonly in the spine, hip and wrist, but can occur in any bone.Osteoporosis has been called “a pediatric disease with geriatric consequences,” because the bone mass attained in childhood and adolescence is an important determinant of lifelong skeletal health. The health habits your kids are forming now, can make, or literally break, their bones as they age. Fast Facts
80% of patients affected by osteoporosis are female
related fracture in their lifetime Responsible for greater than 1.5 million fractures annually A woman with a hip fracture is 4 times at risk to develop a second fracture
WHAT IS BONE? In order to understand osteoporosis, it is important to learn about bone. Made mostly of collagen, bone is a living, growing tissue. Collagen is a protein that provides a soft framework. Calcium phosphate is a mineral that adds strength and hardens the framework. This combination of collagen and calcium makes bone strong enough to withstand stress. More than 99 percent of the body’s calcium is contained in the bones and teeth. The remaining 1 percent is found in the blood. There are two types of bone found in the body – cortical and trabecular. Cortical bone is dense and compact. It forms the outer layer of the bone. Trabecular bone makes up the inner layer of the bone and has a spongy, honeycomb-like structure. Bone continually undergoes a two-part process called remodeling, or bone turnover. It involves two distinct stages: bone resorption (breakdown) and bone formation. Calcium is stored in bone. When it is needed in the body, bone resorption increases. Bone cells called osteoclasts attach to the bone surface and break it down, leaving cavities in the bone and releasing calcium. In bone formation, bone-forming cells called osteoblasts move in and release collagen and other proteins into these cavities and stimulate bone mineralization. The osteoblasts then join with calcium and other substances to form new bone material (matrix) to replace what was lost. Some of these osteoblasts which remain part of the matrix are called osteocytes. Osteoclast and osteoblast function is regulated by several hormones including calcitonin, parathyroid hormone, vitamin D, estrogen (in women) and testosterone (in men), among others.
In order to be able to make “deposits” of bone tissue and reach the greatest possible peak bone mass, you need to get enough calcium, vitamin D, and exercise – important factors in building bone. After age 30, bone “withdrawals” can begin to exceed “deposits.” For many people, this bone loss can be prevented by continuing to get calcium, vitamin D, and exercise and by avoiding tobacco and excessive alcohol use. Your body continually removes and replaces calcium from the bone. If more calcium is removed than replaced, the bone becomes weaker and has a greater chance of breaking. Osteoporosis develops when either bone removal occurs too quickly or replacement occurs too slowly or both. You are more likely to develop osteoporosis if you did not reach your maximum peak bone mass during your bone building years. Factors Affecting Peak Bone Mass Peak bone mass is influenced by a variety of factors: some that you can’t change, like gender and race, and some that you can, like nutrition and physical activity. Gender: Bone mass or density is generally higher in men than in women. Before puberty, boys and girls develop bone mass at similar rates. After puberty, however, boys tend to acquire greater bone mass than girls. Race: For reasons still not well understood, African-American girls tend to achieve higher peak bone mass than Caucasian girls, and African-American women are at lower risk for osteoporosis later in life. More research is needed to understand the differences in bone density between the various racial and ethnic groups. However, because all women, regardless of race, are at significant risk for osteoporosis, girls of all races need to build as much bone as possible to protect themselves against this disease. Hormonal factors: Sex hormones, including estrogen and testosterone, are essential for the development of bone mass. Girls who start to menstruate at an early age typically have greater bone density. Those who frequently miss their menstrual periods sometimes have lower bone density. Nutritional status: Calcium is an essential nutrient for bone health. In fact, calcium deficiencies in young people can account for a 5 to10 percent lower peak bone mass and may increase the risk for bone fracture in later life. A well-balanced diet including adequate amounts of vitamins and minerals such as magnesium, zinc, and vitamin D is also important for bone health. Physical activity: Important for building healthy bones, physical activity provides benefits that are most pronounced in the areas of the skeleton that bear the most weight. These areas include the hips during walking and running and the arms during gymnastics and weight lifting. DETECTION Special tests to assess osteoporosis are called Bone Mineral Density tests. BMD tests measure bone density, or amount of calcium buildup at various sites. These tests can detect osteoporosis, predict chances of fracture in the future, and determine the rate of bone loss with repeated tests every 2 years. The National Osteoporosis Foundation recommends BMD tests in the following: all female patients over 65, younger, post-menopausal women with greater than one risk factor for osteoporosis, and post-menopausal women who present with a fracture to confirm the diagnosis and determine bone density. Bone Mineral Density testing is painless, noninvasive and safe. Bone mineral testing when completed is compared to 2 standards. The first standard is age matched (Z score) — it compares the patient’s bone density to the expected density of someone of the same age, sex and size. The second standard is the young normal (T score) — it compares the patient’s bone density to the optimal peak density of a healthy young adult of the same sex. TREATMENTS Medication Although there is no cure for osteoporosis, medications may be used to prevent and or treat osteoporosis. These medications include Bisphosphonates, Estrogen/Hormone Therapy, and Selective Estrogen Receptor Modulators (SERMs). Bisphosphonates affect the bone remodeling cycle and are classified as anti-resorptive medications. Anti-resorptive medications slow or stop the bone-resorbing portion of the bone remodeling cycle. They do not slow the boneformation portion of the cycle. As such — the new bone formation builds faster than the resorption, therefore the bone density may increase over time. Estrogen or Hormone therapy has been shown to reduce bone loss and increase the bone density in both the spine and the hip. Due to the increased risk of developing other cancers with continued estrogen use, Healthcare providers prescribe the hormone progestin with estrogen to minimize this risk. Selective Estrogen Receptor Modulators (SERMs) have been developed to provide the beneficial effects of estrogens without the potential disadvantages and side effects. Nutrition Calcium is essential for many of the body’s functions. Calcium is a mineral found in many foods. Adequate calcium intake is important because the human body cannot produce calcium. When reaching full skeletal growth, adequate calcium intake is important because the body loses calcium every day through the skin, nails, hair and sweat. Lost calcium is replaced daily from the diet. Without adequate intake through the diet, the body tries to replenish it by absorbing it through the bone. With increased amounts of calcium loss, the bone becomes weaker and more susceptible to fractures. Vitamin D helps the body absorb calcium. It allows the body to absorb calcium into the bloodstream. The active or body tolerant form of vitamin D is activated by skin exposure to sunlight. 10-15 minutes a day of sunlight exposure to the hands and face will allow the vitamin D to become active and allow the body to absorb calcium. The recommendation for Vitamin D intake is 200-600 IU a day. PREVENTION Childhood Bone Development Experts believe calcium should come from food sources whenever possible. However, if you think your children are not getting adequate calcium from their diet, you may want to consider a calcium supplement. For optimal absorption, no more than 500 mg of calcium should be taken at one time. Muscles get stronger when we use them. The same idea applies to bones: the more work they do, the stronger they get. Any kind of physical exercise is great for your kids, but the best ones for their bones are weightbearing activities like walking, running, hiking, dancing, tennis, basketball, gymnastics, and soccer. (Children who tend to play outside will also have higher vitamin D levels.) Swimming and bicycling promote your kids’ general health, but are not weight-bearing exercises and will not help build bone density. Organized sports can be fun and build confidence, but they are not the only way to build healthy bones. Osteoporosis is rare among children and adolescents. When it occurs, it is usually caused by an underlying medical disorder or by medications used to treat such disorders. If you are concerned about your child’s frequent fractures, talk to their doctor for more information. Beyond Childhood By age 20 the average female has acquired 98% of her skeletal mass. Therefore building strong bones during childhood and adolescence is the best defense. To optimize bone health — the following guidelines should be considered:
Risk Factors Factors which increase the likelihood of developing osteoporosis may include:
World Health Organization Definitions of Osteoporosis Based on Bone Density Levels (T score)
Recommended Calcium Intakes* Age Amount of calcium Infants
Children/Young Adults
Adult Women and Men
Pregnant or Lactating Women
* Source: National Academy of Sciences, 1997. Sources
|
|||||||||||||||||||||||||||||||||
|
|||||||||||||||||||||||||||||||||
Think of bone as a bank account where you “deposit” and “withdraw” bone tissue. During childhood and the teenage years, new bone is added to the skeleton faster than old bone is removed. As a result, bones become larger, heavier, and denser. For most people, bone formation continues at a faster pace than removal until bone mass peaks during the third decade of life.
