What Causes Osteoporosis?
Osteoporosis occurs when there is an imbalance between new bone formation and old bone resorption. The body may fail to form enough new bone, or too much old bone may be reabsorbed, or both. Two essential minerals for normal bone formation are calcium and phosphate. Throughout youth, the body uses these minerals to produce bones. Calcium is essential for proper functioning of the heart, brain, and other organs. To keep those critical organs functioning, the body reabsorbs calcium that is stored in the bones to maintain blood calcium levels. If calcium intake is not sufficient or if the body does not absorb enough calcium from the diet, bone production and bone tissue may suffer. Thus, the bones may become weaker, resulting in fragile and brittle bones that can break easily.
Usually, the loss of bone occurs over an extended period of years. Often, a person will sustain a fracture before becoming aware that the disease is present. By then, the disease may be in its advanced stages and damage may be serious.
The leading cause of osteoporosis is a lack of certain hormones, particularly estrogen in women and androgen in men. Women, especially those older than 60 years of age, are frequently diagnosed with the disease. Menopause is accompanied by lower estrogen levels and increases a woman's risk for osteoporosis. Other factors that may contribute to bone loss in this age group include inadequate intake of calcium and vitamin D, lack of weight-bearing exercise, and other age-related changes in endocrine functions (in addition to lack of estrogen).
Other conditions that may lead to osteoporosis include overuse of corticosteroids (Cushing syndrome), thyroid problems, lack of muscle use, bone cancer, certain genetic disorders, use of certain medications, and problems such as low calcium in the diet.
The following are risk factors for osteoporosis:
- Women are at a greater risk than men, especially women who are thin or have a small frame, as are those of advanced age.
- Women who are white or Asian, especially those with a family member with osteoporosis, have a greater risk of developing osteoporosis than other women.
- Women who are postmenopausal, including those who have had early or surgically induced menopause, or abnormal or absence of menstrual periods, are at greater risk.
- Cigarette smoking, eating disorders such as anorexia nervosa or bulimia, low amounts of calcium in the diet, heavy alcohol consumption, inactive lifestyle, and use of certain medications, such as corticosteroids and anticonvulsants, are also risk factors.
- Rheumatoid arthritis itself is a risk factor for osteoporosis.
- Having a parent who has/had osteoporosis is a risk factor for the offspring.
Osteoporosis (meaning porous bone) is a bone disease in which bone loss occurs, so that bones become weak and are more likely to break. Without prevention or treatment, osteoporosis can progress without pain or symptoms until a bone breaks (fractures). Fractures from osteoporosis commonly occur in the hip, spine, ribs, and wrist.
What Are Symptoms and Signs of Osteoporosis?
Early in the course of the disease, osteoporosis may cause no symptoms. Later, it may cause height loss or dull pain in the bones or muscles, particularly low back pain or neck pain.
Later in the course of the disease, sharp pains may come on suddenly. The pain may not radiate (spread to other areas); it may be made worse by activity that puts weight on the area, may be accompanied by tenderness, and generally begins to subside in one week. Pain may linger more than three months.
People with osteoporosis may not even recall a fall or other trauma that might cause a broken bone, such as in the spine or foot. Spinal compression fractures may result in loss of height with a stooped posture (called a dowager's hump).
Fractures at other sites, commonly the hip or bones of the wrist, usually result from a fall.
When Should Someone Seek Medical Care for Osteoporosis?
If you are past menopause and have constant pain in areas such as the neck or lower back, consult your doctor for further evaluation. If you are at risk for developing osteoporosis (see risk factors above), also consult your doctor for a medical assessment and bone density screening.
Go to the hospital if you feel severe pain in your muscles or bones that limits your ability to function. Go to the hospital's emergency department if you have sustained trauma or suspect fractures of your spine, hip, or wrist.
What Exams and Tests Do Health-Care Professionals Use to Diagnose Osteoporosis?
The doctor will usually begin with a careful history to determine if you have osteoporosis or if you may be at risk for the disease. You will be asked a variety of questions regarding lifestyle and other conditions that you may have. The doctor will also ask if you have a family history of osteoporosis or a history of previous broken bones. Often blood tests are used to measure calcium, phosphorus, vitamin D, testosterone, and thyroid and kidney function.
Based on a medical examination, the doctor may recommend a specialized test called a bone mineral density test that can measure bone density in various sites of the body. The diagnosis of osteoporosis or osteopenia can be made based on the results of these tests. Osteopenia is lower-than-normal bone density not severe enough to be classified as osteoporosis and is considered by many experts to be a precursor to osteoporosis. A bone mineral density test can detect osteoporosis before a fracture occurs and can predict future fractures. A bone mineral density test can also monitor the effects of treatment if the tests are performed a year or more apart and may help determine the rate of bone loss.
A. Normal spine, B. Moderately osteoporotic spine, C. Severely osteoporotic spine. Click to view larger image.
- Several different machines measure bone density. All are painless, noninvasive, and safe. They are becoming more readily available. In many testing centers, you don't even have to change into an examination robe. Central machines may measure density in the hip, spine, and total body. Peripheral machines may measure density in the finger, wrist, kneecap, shinbone, and heel.
- The DXA (dual-energy X-ray absorptiometry) measures the bone density of the spine, hip, or total body. With your clothes on, you simply lie on your back with your legs on a large block. The X-ray machine moves quickly over your lower spine and hip area.
- SXA (single-energy X-ray absorptiometry) is performed with a smaller X-ray machine that measure bone density at the heel, shinbone, and kneecap. Some machines use ultrasound waves pulsing through water to measure the bone density in your heel. You place your bare foot in a water bath, and your heel fits into a footrest as sound waves pass through your ankle. This is a simple way to screen large numbers of people quickly. You might find this type of screening device at a health fair. Bone loss at the heel may mean bone loss in the spine, hip, or elsewhere in the body. If bone loss is found in this test, you might be asked to have the DXA to confirm the results and get a better measurement of your bone density.
- The result of the bone mineral density is compared to two standards, or norms, known as "age matched" and "young normal." The age-matched reading compares your bone mineral density to what is expected of someone of your age, sex, and size. The young normal reading compares your density to the optimal peak bone density of a healthy young adult of the same sex. The information from a bone mineral density test enables the doctor to identify where you stand in relation to others your age and to young adults (which is presumed to be your maximum bone density). Scores significantly lower than "young normal" indicate you have osteoporosis and are at risk for bone fractures. The results will also help the doctor to decide the best way to manage your bone health. For patients who have borderline results, an especially helpful new method of determining the 10-year probability of fracturing bone can be determined using a program called FRAX. This computation method is available online and takes into account all risk factors for a given individual to determine their personal risk for fracture and, therefore, need for treatment.
What Is the Medical Treatment for Osteoporosis?
Treatment for osteoporosis focuses on slowing down or stopping the mineral loss, increasing bone density, preventing bone fractures, and controlling the pain associated with the disease.
Some 40% of women will experience a broken bone (fracture) due to osteoporosis during their lifetime. In those who have a vertebral fracture (in their back), one in five will suffer another vertebral fracture within one year. This condition potentially leads to more fractures. This is called a "fracture cascade." The goal of treatment is to prevent fractures.
- Diet: Young adults should be encouraged to achieve normal peak bone mass by getting enough calcium (1,000 mg daily) in their diet (drinking milk or calcium-fortified orange juice and eating foods high in calcium such as salmon), performing weight-bearing exercise such as walking or aerobics (swimming is aerobic but not weight-bearing), and maintaining normal body weight.
- Specialists: People who have spinal, hip, or wrist fractures should be referred to a bone specialist (called an orthopedic surgeon) for further management. In addition to fracture management, these people should also be referred to a physical and occupational therapist to learn ways to exercise safely. For example, someone with spinal fractures would avoid touching their toes, doing sit-ups, or lifting heavy weights. Many types of doctors treat osteoporosis, including internists, generalists, family physicians, rheumatologists, endocrinologists, and others.
- Exercise: Lifestyle modification should also be incorporated into your treatment. Regular exercise can reduce the likelihood of bone fractures associated with osteoporosis.
- Studies show that exercises requiring muscle to pull on bones causes the bones to retain, and perhaps even gain, density.
- Researchers found that women who walk a mile a day have four to seven more years of bone in reserve than women who don't.
- Some of the recommended exercises include weight-bearing exercise, riding stationary bicycles, using rowing machines, walking, and jogging.
- Before beginning any exercise program, make sure to review your plan with your doctor.
Are There Home Remedies for Osteoporosis?
If you suspect that you have signs or symptoms of osteoporosis or have risk factors for osteoporosis, see your doctor for further evaluation and treatment.
Which Doctors Treat Osteoporosis?
Osteoporosis may be treated by a number of different medical specialists. Endocrinologists, rheumatologists, family practitioners, generalists, internists, geriatricians, and gynecologists all treat osteoporosis.
Can Any Foods Help Prevent Osteoporosis?
Many foods can help prevent osteoporosis. A number of scientific studies have shown that eating more fruits and vegetables leads to stronger bones. Low-fat dairy products are high in calcium, and many are fortified with vitamin D and help strengthen bones. Fatty fish such as salmon, mackerel, tuna, and sardines are high in vitamin D. Canned sardines and salmon (with bones) are high in calcium.
What Foods Should Be Avoided With Osteoporosis?
- Foods that are high in sodium (salt) cause the body to lose calcium and can lead to bone loss.
- Drinking too much alcohol can lead to bone loss. Limit alcohol intake to two drinks a day or less.
- Caffeine found in coffee, tea, and soda decreases calcium absorption and can lead to bone loss.
- Soft drinks. The caffeine and phosphorous found in colas may contribute to bone loss. It is not clear if the link to bone loss is because people choose soft drinks over milk and other calcium-containing beverages, or if cola directly causes bone loss.
What Medications Treat Osteoporosis?
- Estrogen: For newly menopausal women, estrogen replacement is one way to prevent bone loss. Estrogen can slow or stop bone loss. And if estrogen treatment begins at menopause, it can greatly reduce the risk of hip fracture. It may be taken orally or as a transdermal (skin) patch (for example, Vivelle, Climara, Estraderm, Esclim, Alora).
- Many women past menopause also choose estrogen replacement therapy because of its proven usefulness in slowing the progression of, or preventing, osteoporosis.
- Recent studies question the safety of long-term estrogen use. Women who take estrogen have an increased risk for developing certain cancers. Although it was once thought that estrogens confer a protective effect on the heart and blood vessels, recent studies have shown that estrogens cause an increase in coronary heart disease, stroke, and venous thromboembolism (blood clots). Many women who take estrogens have side effects (such as breast tenderness, weight gain, and vaginal bleeding). Estrogen's side effects can be reduced with proper dosing and combination. If you have had a hysterectomy, estrogen alone is needed. For women with an intact uterus, progestin is always part of hormone replacement therapy. Ask your doctor whether estrogen is right for you.
- SERMs: For women who are unable to take estrogen or choose not to, selective estrogen receptor modulators (SERMs) such as raloxifene (Evista) offer an alternative. For example, many women who have first-degree relatives with breast cancer will not consider estrogen. The effects of raloxifene on bone and cholesterol levels are comparable to those of estrogen replacement. There appears to be no estrogen stimulation of the breasts or uterine lining, which reduces the risk profile of hormone replacement. Raloxifene may cause hot flashes. Its risk of blood clots is at least comparable to the risks with estrogen. Tamoxifen (Nolvadex), commonly used in the treatment of certain breast cancers, also inhibits bone breakdown and preserves bone mass.
- Calcium: Calcium and vitamin D are needed to increase bone mass in addition to estrogen replacement therapy.
- A daily intake of 1,200-1,500 mg (through diet and supplements) is recommended. Take calcium supplements (calcium carbonate, calcium citrate) in doses of less than 600 mg. Your body can only absorb so much at one time. The best way may be to take one supplement with breakfast and another with dinner.
- A daily intake of 800-1,000 IU of vitamin D is needed to increase bone mass. Vitamin D is available over the counter as vitamin D2 and vitamin D3 (cholecalciferol).
Bisphosphonates and Other Hormones
- Bisphosphonates: Other treatments for osteoporosis are available. Bisphosphonate medications taken by mouth include alendronate, risedronate, etidronate; intravenous medications include the bisphosphonate zoledronate (Reclast). These drugs slow down bone loss, and in some cases, they actually increase bone mineral density. Doctors can measure the effects of these drugs by obtaining DXAs every year or two and comparing the measurements. When taking these drugs, it is important to stand or sit upright for 30 minutes after swallowing the medication. This helps decrease the risk of heartburn and ulcers in the esophagus. After taking bisphosphonates, you must wait 30 minutes to ingest food, beverages (except water), and other medications, including vitamins and calcium. Before beginning to take a bisphosphonate, your doctor will determine if you have enough calcium in your blood and if your kidneys are functioning well.
- Alendronate (Fosamax): This medication is used to treat osteoporosis and to prevent bone loss in women. In clinical trials, alendronate has been shown to reduce the risk of new spinal and hip fractures by 50%. Gastrointestinal problems, such as nausea, acid reflux symptoms, and constipation, are the most common side effects. You must take this medication first thing in the morning with a large glass of water and not lie down or eat for 30 minutes. Some women find this restriction difficult. This medication is taken daily or once a week.
- Risedronate (Actonel): This medication is used for the treatment and prevention of osteoporosis. Gastrointestinal upset is the most common side effect. Women with severe kidney impairment should avoid this drug. Results from a recent study showed that daily risedronate use can lead to a significant reduction in new vertebral fractures (62%) and multiple new vertebral fractures (90%) in postmenopausal women with osteoporosis, compared with a similar group who did not take this medication.
- Etidronate (Didronel): This drug has been approved by the U.S. FDA for the treatment of Paget's disease, another bone condition. Doctors have been using this drug successfully in clinical trials to treat women with osteoporosis.
- Ibandronate (Boniva): This drug is an FDA-approved bisphosphonate and is used to prevent or treat osteoporosis in postmenopausal women.
- Zoledronate (Reclast): This is a powerful intravenous bisphosphonate that is given once a year. This can be especially beneficial for patients who cannot tolerate oral bisphosphonates or are having difficulty with complying with the required regular dosing of oral medications.
- Other hormones: These hormones help regulate calcium and/or phosphate levels in the body and prevent bone loss.
- Calcitonin (Miacalcin): Calcitonin is a hormone (extracted from salmon) that slows bone loss and may increase bone density. You may be given this drug as an injection (every other day or two to three times a week) or as a nasal spray.
- Teriparatide (Forteo): Teriparatide contains a portion of human parathyroid hormone. It primarily regulates calcium and phosphate metabolism in bones, which promotes new bone formation and leads to increased bone density. This drug is given as a daily injection.
For more information, see Understanding Osteoporosis Medications.
Is Follow-up Needed After Osteoporosis Treatment?
If you are being treated with estrogen replacement therapy, be sure to have routine mammograms, pelvic exams, and Pap smears as recommended to monitor the possible medication side effects. If you are on non-hormonal treatment, have urine and kidney function tests and routine follow-up visits with your doctor.
Arrow indicates vertebral fractures Click to view larger image.
Is It Possible to Prevent Osteoporosis?
Building strong bones during childhood and adolescence can be the best defense against developing osteoporosis later. The average woman has acquired 98% of her skeletal mass by 30 years of age.
There are four steps to prevent osteoporosis. No one step alone is enough to prevent osteoporosis.
- Eat a balanced diet rich in calcium and vitamin D and high in fruits and vegetables.
- Engage in weight-bearing physical exercise.
- Adopt a healthy lifestyle with no smoking or excessive alcohol intake.
- Take medication to improve bone density when appropriate.
What Is the Prognosis for Osteoporosis?
With adequate treatment, the progression of osteoporosis can be slowed, stopped, or reversed. Nevertheless, some people become severely disabled as a result of weakened bones. Some patients will fracture their hip, pelvis, vertebrae, wrist, humerus, or leg in the year following an osteoporotic vertebral fracture. Hip fractures are a frequent fracture and leave about half of those who break a hip unable to walk independently. Women who have a hip fracture are at fourfold greater risk for a second hip fracture. There is a significant overall increase in mortality (death rate) in the year after a hip fracture. By 80 years of age, 15% of women and 5% of men have hip fractures. Thus, osteoporosis is a serious disease that requires better efforts at prevention, detection, and treatment.
Reviewed on 8/30/2017
"Overview of the management of osteoporosis in postmenopausal women"
"Screening for osteoporosis"