Encyclopedia / O / Osteoporosis


What is Osteoporosis?

Osteoporosis is a progressive skeletal disease characterized by loss of bone mass due to imbalance of bone formation and bone resorption. The condition is characterized by low bone density and bone fragility. Affected bones become porous and brittle and susceptible to fractures, especially at the hip, spine, and wrist.

Two types of bone are affected by osteoporosis: the cortical bone—the compact outer layer of the bone shaft—and the trabecular bone, a meshlike inner structure. Trabecular bone, which is found in high percentages in the hip, spine, and wrist, is more vulnerable because it has a higher turnover rate, which is why wrists and hips, and vertebrae in the spine, are the most common fracture sites.

Osteoporosis develops without warning signs. Most people with osteoporosis do not realize they have the disease until a minor fall results in a fracture.

Who Gets Osteoporosis?

The disease is very common among people over age 70. It affects women four times more often than men, owing to hormonal changes that occur with menopause. Caucasian and Asian women have a higher incidence of osteoporosis compared with other ethnic groups. During childhood and early adulthood, bone formation exceeds bone resorption. According to the U.S. Centers for Disease Control and Prevention, 4.5 million women age 50 and older have osteoporosis of the hip.


Osteoporosis has sometimes been called a "silent disease" because people do not experience symptoms. Symptoms that can indicate osteoporosis include:

  • Lower back pain is usually the result of a vertebral fracture.
  • Gradual loss of height and stooping posture.
  • Wrist, hip, or vertebral fractures.

Causes/Risk Factors

Osteoporosis is associated with aging: By age 35, men and women reach and maintain maximum bone density and strength, called peak bone mass. After the age of 40 or so, resorption exceeds formation, and gradual bone loss begins. But while some degree of loss of bone mass is a normal consequence of aging, a number of other factors hasten bone loss and the development of osteoporosis.

  • Reduced estrogen levels after menopause.

  • Dietary calcium deficiency.

  • Physical inactivity.

  • Excessive alcohol use.

  • Being underweight.

  • Family history.

  • Hereditary factors. For example, white women have a higher incidence of osteoporosis than women of other races.

  • Osteoporosis may occur as a consequence of an underlying condition, such as hyperthyroidism, hyperparathyroidism, premature menopause (before age 45), hypogonadism in men (testosterone deficiency), celiac disease, chronic lung diseases, and Cushing’s disease (excessive production of corticosteroids by the adrenal glands). It may also arise from long-term use of corticosteroid drugs, anti-seizure medications, or heparin (an anticoagulant).

What If You Do Nothing?

If you have osteoporosis and do nothing to stop the loss of bone, the condition will worsen and could have serious implications for your health. Most especially, doing nothing can significantly increase the risk of bone fractures.


  • Patient history and physical examination.
  • Bone density scan.
  • Imaging tests. X-rays or computed tomography scans can detect bone loss related to osteoporosis. Routine x-rays, however, do not detect osteoporosis until 25 percent or more bone mass has been lost.
  • Blood or urine tests
  • Bone biopsy to detect or rule out other causes of bone loss, but this is not common.


Treating osteoporosis can include lifestyle changes, hormone therapy, and medications, depending on the severity of symptoms and the risk for new or recurrent fractures.

  • Get adequate amounts of calcium, vitamin Dand phosphorus to encourage bone growth and maintain health. Calcium-rich foods include dairy products, such as cheese, milk and yogurt, tofu, collard greens, kale and broccoli, and even fish, such as sardines and salmon. Vitamin D can also be found in sardines and salmon, fortified cereals and dairy products, beef liver, cheese, and egg yolks. Earlier research had suggested calcium and vitamin D supplements could improve bone health, but more recent recommendations from the U.S. Preventive Services Task Force, an independent panel of experts that advices the federal government, indicate that calcium and vitamin D supplements do not protect against fractures and may increase the risk for kidney stones.
  • Do weight-bearing exercise. Walking, jogging, hiking, and dancing have several positive effects, the foremost being an increase in bone density. Exercise also increases strength, coordination, and balance, thereby reducing the risk for falls. Twenty minutes of exercise three or four times per week is recommended. Women should consult their physicians when beginning an exercise program.
  • The bisphosphonate drugs alendronate (Fosamax) and risedronate (Actonel) slow bone resorption and increase bone density. Studies of postmenopausal women report a substantial decrease in the risk for fractures in the spine and hip. Dosage depends on whether the medication is prescribed for prevention or treatment. Bisphosphonates may cause gastrointestinal disturbance such as nausea and heartburn.
  • Raloxifine (Evista), a selective estrogen receptor modulator (SERM), produces some of the same benefits as estrogen replacement therapy without the side effects. Raloxifine is used both to prevent and to treat osteoporosis. Studies show it prevents bone loss and reduces the risk for spinal fractures. In addition to small increases in bone mass in sites typically associated with osteoporosis, raloxifine encourages bone density throughout the body.
  • High doses of calcitonin (a hormone that regulates the body’s useage of calcium) can slow bone loss and possibly add bone mass.
  • Zoledronic acid (Reclast Injection, Zometa Injection) is approved for the treatment of osteoporosis in postmenopausal women. Reclast is given intravenously once a year. In rare cases, women receiving this treatment have experienced deterioration (osteonecrosis) of the jaw. Prior to treatment, an oral examination should be performed.  Reclast has also been approved to prevent new fractures in postmenopausal women with osteoporosis who had already experienced low-trauma hip fracture.
  • Estrogen treatment may be recommended for women at high risk for osteoporosis or who have osteoporosis. Women who have had a hysterectomyor an oophorectomy (removal of the ovaries) before age 50, have experienced natural menopauseand have multiple risk factors for osteoporosis, or have below normal bone mass for their age are good candidates for hormone therapy. When hormone therapy is taken by postmenopausal women, there is a slower rate of bone loss and increased bone mass in the spine and hip. With 10 or more years of use, a
  • Forteo, an injectable synthetic parathyroid hormone, is used to treat postmenopausal women at high risk for fracture. This drug acts on bone-building cells (osteoblasts) to stimulate new bone growth and increase bone mineral density. Combination therapy with hormone therapy has been shown to be effective.


  • An active, healthy lifestyle that includes a well-balanced diet can help reduce the risk of osteoporosis. Certain safety measures (such as using a cane or walker for balance and removing throw rugs and clutter from ones living space) may also reduce the risk for falling and bone fractures. Calcium in particular is essential for bone health. Older men and postmenopausal women should get 1,500 milligrams of calcium per day, which may require the use of calcium supplements.
  • Vitamin D aids in the intestinal absorption of calcium and phosphorus. Twenty minutes of sun each day satisfies the daily-recommended intake; however, additional vitamin D may be necessary. If taken in a supplement, 400 IU to 800 IU per day is recommended. The dosage should not exceed 2000 IU daily because of possible liver damage. Foods containing vitamin D include eggs, fatty fish, cereal, and milk fortified with vitamin D. Both calcium and vitamin D supplements are best absorbed when taken with food.
  • Get regular weight-bearing exercise, which helps to maintain and even increase bone density. Recommended exercises include aerobics, dancing, jogging, hiking, stair climbing, and walking.
  • Don't smoke. Smoking interferes with the absorption of calcium and is associated with lower estrogen levels, early onset of menopause, and an increased need for hormone therapy after menopause. Smoking cessation reduces the risk for osteoporosis.

When To Call A Doctor

  • Consider being screened for osteoporosis if you have a family history, are a woman over 65, are considering hormone replacement therapy, or have experienced a nontraumatic fracture.
  • See a doctor if you have any symptoms of osteoporosis.
  • If you have osteoporosis and pain develops after any strain or injury, call a doctor immediately.

Robert Hurd, M.D., American Board of Internal Medicine and Professor of Endocrinology and Health Care Ethics, Xavier University, Cincinnati, OH. Review provided by VeriMed Healthcare Network