One of the most serious consequences of postmenopausal aging is the development of osteoporosis. In fact, osteoporosis is a major health problem affecting more than 25 million older Americans, 90 percent of them women. One out of three American women will develop osteoporosis, most after menopause.
The statistics surrounding osteoporosis are astounding. More than 1.3 million fractures occur each year as a result of this condition. Eighty percent of the 250,000 hip fractures in the United States each year occur in women over age 65 as a result of osteoporosis. About one-quarter of these women die within one year from complications, such as blood clots and pneumonia, caused by their convalescence. Another one-third never regain the ability to function physically or socially on their own. These women spend the rest of their lives requiring long-term care in nursing facilities. In addition to causing hip fractures, osteoporosis is also responsible for loss of bone in the jaw, gum recession (both of which are early signs of this condition), dowager's hump, loss of height, back pain due to compression and fractures of the vertebra, and fractures of the wrist (called colles fractures by physicians).
Often these fractures occur when only mild stress is put on the bone. This can include missing a step and falling down, falling on an extended arm or lifting a heavy object. Because of the underlying weakness of the bone, fractures can also occur spontaneously without any preceding trauma. This often occurs with vertebral fractures.
This chapter will discuss what happens to bones with osteoporosis, risk factors for osteoporosis, diagnosis of osteoporosis and other structural changes associated with menopause. Finally, therapies for osteoporosis and other structural changes will be explored.
What Happens to Bones with Osteoporosis
Bones are living tissue; we are constantly forming new bone cells to add to our skeletal mass and removing old cells that are no longer useful. This simultaneous addition and subtraction of bone from our skeleton is called bone remodeling; from five to ten percent of our bone is replaced through this process every year. Bone remodeling involves two types of bone cells. Osteoblasts create new bone cells, while osteoclasts are responsible for removing old cells from the skeleton. This delicately balanced process is carefully regulated by many of the hormones in our body such as estrogen, progesterone, calcitonin and thyroid (as well as other hormones).
During the first 30 to 35 years of life, we deposit more bone in our skeleton than we lose, provided our health status is normal. In fact, our bone mass is at its peak in our 20s and begins to decrease in the mid-30s. According to peak bone mass theory, our bones reach their peak level of healthy density by the early 20s. The more healthy our bones are at this stage, the less risk of osteoporosis later in life. In the years preceding menopause, bone loss begins to exceed the addition of new bone to the skeleton. As a result, bones begin to lose important minerals such as calcium, as well as their matrix or intracellular substance. This causes a decrease in bone density as well as an increased brittleness or porousness of the bones
Initially, this process occurs very slowly, and women are not even aware that it is going on. However, with loss of hormonal support to the bones at the time of menopause, this process accelerates. The first years after the onset of menopause can be a time of rapid bone loss for many women unless they have instituted therapies that emphasize prevention. Bone is lost at the rate of one to three percent per year for five to ten years after menopause. If the process of bone loss continues unabated, osteoporosis may eventually result. Unfortunately, most women are unaware that they are losing bone during their early postmenopausal years. By the time osteoporosis becomes apparent as they begin to suffer from pain and fractures, women are already in their 60s or 70s. Older women with osteoporosis may have lost as much as 40 to 45 percent of their total bone mass.
Men also start to lose bone mass around age 40 (approximately three to five percent per decade). However, they have thicker bones to start with; men have approximately 30 percent more bone mass than women. In addition, the male hormone, testosterone, helps maintain bone mass and strength. Both estrogen in women and testosterone in men help control calcium absorption by the bones. These hormones prevent the resorption of calcium from the bones into the blood circulation where calcium can be excreted from the body. However, unlike women whose estrogen levels drop precipitously at menopause, men can maintain their testosterone levels well into old age. As a result, their bones remain thicker and stronger far longer than those of women. This translates into more osteoporosis related fractures for women than men eight times more hip fractures and ten times more wrist fractures.
Although gender and age contribute greatly to the fractures that occur in old age because of osteoporosis, these are not the only factors. Many physicians also attribute fractures in the elderly to poor balance and lack of ability to right oneself when tripping or stumbling. Many older people lack flexibility, so when they fall, they absorb a much greater shock than if they could cushion themselves effectively or right themselves quickly. As a result, hip fractures increase with age, mirroring the loss of agility that occurs for many elderly women (and men).
Risk Factors for Osteoporosis
Not all women have the same risk of developing osteoporosis. Some women maintain strong and heavy bones throughout their lives, while other women develop accelerated bone loss soon after menopause. If you suspect you are at risk of developing osteoporosis, become knowledgeable about which factors have been linked to a higher incidence of this disease. This will help you and your physician evaluate your risk when planning an optimal treatment program. These factors include racial background, family history, hormonal status, lifestyle habits and pre-existing health conditions.
Skin pigmentation appears to parallel bone mass. African-American women are less likely to develop osteoporosis than white women. In fact, women at the highest risk are small and fairskinned. These are typically women of Northern European ancestry such as Dutch, German or English background with blond, reddish or light brown hair and pale skin. Oriental women have a higher risk of developing osteoporosis, too. Even among similar groups, the risk is lower with women who have darker skin. For example, in Israel the darker skin Sephardic Jews have a lower rate of fractures than do Jewish women of European origin.
If your close female relatives suffered from osteoporosis, you have a higher risk of developing this problem. Many women have seen their mothers or grandmothers develop a dowager's hump or become disabled after suffering a hip fracture. This can be quite upsetting for the entire family who must deal with the longterm disability.
The age at which women begin menopause and how much hormonal support they maintain during their postmenopausal years affects bone density. Women who have had a surgical menopause before age 40 with removal of their ovaries are at high risk of osteoporosis because of the abrupt withdrawal of estrogen at a young age. Similarly, women who go through an early natural menopause are at high risk. A woman going through early menopause at age 35 or 40 has as much as 10 to 15 years less estrogen protection for her bones than a woman going through menopause at age 50. Thus, the older you are when going through menopause, the more years of hormonal protection are provided for your bones.
Although obesity is a health risk for many diseases such as osteoarthritis and uterine cancer, being overweight does offer some protection against osteoporosis in postmenopausal women. This is because the fat cells produce a type of estrogen called estrone through conversion of an adrenal hormone called androstenedione. This type of estrogen provides some support for the bones once the ovarian source of estrogen has dwindled.
Women who engage in regular physical exercise and are more muscular have a lower risk of developing osteoporosis. Physical activity also helps keep women flexible and agile which reduces the likelihood of fractures. Conversely, inactivity increases your risk. Young women and men confined to bed for long periods show a decrease in bone mass.
Many nutritional factors affect your risk of developing osteoporosis, too. Women who drink more than two cups of coffee per day or large amounts of other caffeine-containing beverages such as black tea or colas, or who consume more than two alcoholic drinks per day, are at higher risk. Smokers also run a higher risk of osteoporosis. High protein or salt intake are risk factors, as is inadequate calcium intake. When you do not have an adequate intake of calcium, the body takes it from your bones to maintain a blood level necessary for various processes such as heart rhythm and blood clotting.
Pre-Existing Health Issues
Women with a history of bulimia, anorexia or malabsorption syndrome have an increased risk of poor calcium absorption or low estrogen levels (often the case in women with anorexia who do not have a body fat level high enough to produce adequate estrogen). Women who use thyroid medication, suffer from an overactive thyroid gland, or use cortisone for a variety of chronic conditions are at higher risk. This is also true of women with chronic kidney disease. All these conditions can adversely affect calcium balance in the body.
Risk Factors for Osteoporosis
Diagnosis of Osteoporosis
- Membership in a nonblack ethnic group
- Fair, pale skin color
- Having female relatives with osteoporosis
- Early menopause (before age 40)
- Being short and thin
- High alcohol use (more than 5 ounces per day)
- High caffeine use
- Low calcium diet
- Lack of vitamin D
- High-salt diet
- High-protein diet
- Chronic diarrhea or surgical removal of stomach or small intestine
- Lactose deficiency
- Daily use of cortisone
- Use of thyroid medication (over 2 grains), Dilantin, or aluminum-containing antacids
- Uremia (kidney disease)
If you are not sure about the status of your bones, excellent tests are available to evaluate the likelihood of developing osteoporosis. The tests also allow physicians to diagnose osteoporosis in the early stages before the bone loss is so severe that fractures occur. These tests include the single photon densitometer, which measures the density of the forearm; dual photon densitometer, which measures the spine or hip bone; and computerized axial tomography (also called a CAT scan), which can measure bone density in the spine. The CAT scan uses higher x-ray dosages and is a more expensive test. These tests are much more sensitive than conventional x-ray, which picks up osteoporosis only when 30 percent or more of the bone mass is lost.
You may choose to have a bone density test done if you are trying to decide whether or not to use HRT. If the tests show accelerated bone loss for your age group, you should seriously consider the use of HRT unless other major health issues contraindicate the use of hormones.
Another test for osteoporosis involves collecting a 24 hour urine sample. The laboratory then determines the ratio in the urine of calcium to a chemical called creatinine. A high calcium ratio indicates increased calcium excretion and accelerated bone loss.
Other Structural Changes Associated With Menopause
The loss of hormonal support affects not only the bones and teeth but other structural elements of the body such as the joints, muscles, body shape, skin and hair. Although bone loss may occur silently for many years, women notice changes in these other structural elements within a few years of entering menopause.