Osteoporosis

In osteoporosis, a metabolic bone disorder, the rate of bone resorption accelerates while the rate of bone formation slows down, causing a loss of bone mass. Bones affected by this disease lose calcium and phosphate salts and thus become porous, brittle, and abnormally vulnerable to fracture.

Osteoporosis may be primary or secondary to an underlying disease. Primary osteoporosis is often called senile or postmenopausal osteoporosis because it most commonly develops in elderly, postmenopausal women.

Osteoporosis affects over 10 million Americans, with women four times more likely to develop osteoporosis than men. Another 34 million have low bone mass and therefore have an increased risk for osteoporosis. Estrogen deficiency is one of the main causes of bone loss in women during and after menopause. Women may lose up to 20 percent of their bone mass in the five to seven years following menopause.

Causes

The cause of primary osteoporosis is unknown; however, a mild but prolonged negative calcium balance, resulting from an inadequate dietary intake of calcium, may be an important contributing factor-as may declining gonadal adrenal function, faulty protein metabolism due to estrogen deficiency, and a sedentary lifestyle.

Causes of secondary osteoporosis include prolonged therapy with steroids or heparin, total immobilization or disuse of a bone (as with hemiplegia, for example), alcoholism, malnutrition, malabsorption, scurvy, lactose intolerance, hyperthyroidism, osteogenesis imperfecta, and Sudeck's atrophy (localized to hands and feet, with recurring attacks) .

Signs and symptoms

In the early stages of bone loss, you usually have no pain or symptoms. But once bones have been weakened by osteoporosis, you may have signs and symptoms that include:

• Back pain, which can be severe if you have a fractured or collapsed vertebra
• Loss of height over time, with an accompanying stooped posture
• Fracture of the vertebrae, wrists, hips or other bones

Diagnosis

Differential diagnosis must exclude other causes of rarefying bone disease, especially those affecting the spine, such as metastatic carcinoma and advanced multiple myeloma. Initial evaluation attempts to identify the specific cause of osteoporosis through the patient history. Diagnostic tests include the following:

• X-rays show typical degeneration in the lower thoracic and lumbar vertebrae. The vertebral bodies may appear flattened and may look denser than normal. Loss of bone mineral becomes evident in later stages.
• Dual or single photon absorptiometry allows measurement of bone mass, which helps to assess the extremities, hips, and spine.
• Serum calcium, phosphorus, and alkaline phosphatase are all within normal limits, but parathyroid hormone may be elevated.
• Bone biopsy shows thin, porous, but otherwise normal-looking bone.

Treatment

Effective osteoporosis treatment aims to prevent additional fractures and control pain. A physical therapy program, emphasizing gentle exercise and activity, is an important part of the treatment. Estrogen, to be started within 3 years after menopause, may be given to decrease the rate of bone resorption; sodium fluoride, to stimulate bone formation; and calcium and vitamin D, to support normal bone metabolism. However, drug therapy merely arrests osteoporosis and doesn't cure it

Weakened vertebrae should be supported, usually with a back brace. Surgery can correct pathologic fractures of the femur by open reduction and internal fixation. Colles' fracture requires reduction with plaster immobilization for 4 to 10 weeks.

Prevention

Calcium is essential for building and maintaining healthy bone. Vitamin D, which helps your body absorb calcium, is also essential. To get these and other important nutrients throughout life, make sure to keep an overall healthy, well-balanced diet.

To help prevent osteoporosis, don't smoke, and avoid drinking excess alcohol.

Regular exercise can prevent bone fractures. Exercises where muscles pull on bones cause the bones to retain, and possibly gain, density.

A number of new medications for the prevention of osteoporosis, including raloxifene and alendronate, are currently available and FDA approved.