Osteoporosis

Osteoporosis, or porous bone, is a disease characterized by low bone mass and structural deterioration of bone tissue, leading to bone fragility and an increased risk of fractures of the hip, spine, and wrist.

Bone is living tissue that is in a constant state of regeneration, as old bone is removed (bone resorption) and replaced by new bone (bone formation). By their mid-30s, most people begin to gradually lose bone strength as the balance between bone resorption and bone formation shifts, so that more bone is lost than can be replaced. As a result, bones become thinner and structurally weaker.

Symptoms

The disease is referred to as a  “silent disease” because there are no symptoms when you have osteoporosis, and the condition may come to attention only after you break a bone.

When you have osteoporosis, this can occur even after a minor injury, such as a fall. The most common fractures occur at the spine, wrist and hip. Spine and hip fractures in particular may lead to chronic pain, long-term disability and even death.

Statistics

In the U.S., about 8 million women and 2 million men have osteoporosis.

Those over the age of 50 are at greatest risk of developing osteoporosis and suffering related fractures. In this age group, one in two women and one in six men will suffer an osteoporosis-related fracture at some point in their life.

Causes

Many factors will increase your risk of developing osteoporosis and suffering a fracture. Some of these risk factors (like lifestyle factors) can be changed, while others cannot.

Recognizing your own risk factors is important so you can take steps to prevent this condition from developing or treat it before it becomes worse. Major risk factors include:

• Older age (starting in the mid-30s but accelerating after 50 years of age)

• Non-Hispanic white and Asian ethnic background; women
  

• Small bone structure

• Family history of osteoporosis or osteoporosis-related fracture in a parent or sibling

• Previous fracture following a low-level trauma, especially after age 50

• Sex hormone deficiency, particularly estrogen deficiency, both in women (e.g. menopause) and men

• Anorexia nervosa

• Having osteopenia, which is low bone mass

• Medications: glucocorticoid medications such as prednisone (Deltasone, Orasone, etc.), or prednisolone (Prelone); excess thyroid hormone replacement; the blood thinner heparin (Calciparine, Liquaemin, etc.); certain anti-convulsant medications such as phenytoin (Dilantin) etc.

• Certain diseases can affect bone, such as endocrine disorders (hyperthyroidism , hyperparathyroidism, Cushing's disease, etc.) and inflammatory arthritis (rheumatoid arthritis, ankylosing spondylitis, etc.)

Lifestyle factors such as:

• Cigarette smoking

• Alcohol abuse

• Low dietary intake or absorption of calcium and vitamin D

• Sedentary lifestyle or immobility

Diagnosis

Osteoporosis is a silent disease. You might not know you have it until you break a bone.

A simple test that measures bone mineral density (BMD) at different parts of your body, such as your spine and your hip, can help determine if you have osteoporosis.

Dual energy x-ray absorptiometry (DEXA) is the best current test to measure BMD. The test is quick. painless; it is similar to having an x-ray taken, but uses much less radiation. Even so, pregnant women should not have this test to avoid any risk of damaging the developing fetus. The results of the DEXA test are scored in comparison to the BMD of young, healthy individuals, resulting in a measurement called a T-score. If your T-score is –2.5 or lower, you are considered to have osteoporosis and therefore at high risk for a fracture. T-scores between –1.0 and –2.5 are generally considered to show “osteopenia.” The risk of fractures generally is lower in people with osteopenia when compared with those with osteoporosis but, if bone loss continues, the risk for fracture increases.
 

Treatment

A number of medications are also used for the prevention and treatment of osteoporosis:

• Bisphosphonates: Alendronate (Fosamax), risedronate (Actonel) and ibandronate (Boniva) have been FDA-approved for the prevention and treatment of osteoporosis in postmenopausal women. (Alendronate is the only one currently approved for management of osteoporosis in men.) Both alendronate and risedronate are approved for the prevention and treatment of glucocorticoid-induced osteoporosis in men and women. These medications help slow down bone loss and have been shown to decrease the risk of fractures. All are pills that must be taken on an empty stomach with water. Because they have the potential for irritating the esophagus, remaining upright for at least an hour after taking these medications is recommended. Alendronate and risedronate can be taken once a week, while ibandronate can be taken once a month. An IV form of ibandronate, given through the vein every 3 months, also has been FDA-approved for osteoporosis management. Two other IV forms of bisphosphonates available, pamidronate (Aredia) and zoledronic acid or zoledronate (Zometa), are not currently FDA-approved for osteoporosis management.

  Note: There have been reports of jaw osteonecrosis (permanent bone damage of the bones of the jaw) resulting from high dose IV bisphosphonates used primarily in the management of people with underlying cancers. The risk for this problem in those taking these medications at doses recommended for osteoporosis management is not clearly established, but appears to be low. Also note: Use of bisphosphonates in women who are pregnant or breastfeeding is not well studied. Animal studies show that bisphosphonates cross the placenta and enter fetal bone. The risk of fetal harm in humans is theoretical. Thus, the anticipated benefits of bisphosphonates in women who are pregnant or want to become pregnant should be weighed against the potential risks. Calcitonin is safe in pregnancy. Blood calcium levels in women who take bisphosphonates during pregnancy should be monitored.

• Calcitonin (Calcimar, Miacalcin): This medication, a hormone made from the thyroid gland, is given usually as a nasal spray or as an injection under the skin. It has been FDA-approved for the management of postmenopausal osteoporosis and helps prevent vertebral (spine) fractures. It also is helpful in controlling pain after an osteoporotic vertebral fracture.

• Estrogen or Hormone Replacement Therapy: Estrogen therapy alone or in combination with another hormone, progestin, has been shown to decrease the risk of osteoporosis and osteoporotic fractures in women. However, the combination of estrogen with a progestin has been shown to increase the risk for breast cancer, strokes, heart attacks and blood clots. Estrogens alone may increase the risk of strokes. Given the complexity of this decision, consult with your doctor about whether hormone replacement therapy is appropriate for you.

• Selective Estrogen Receptor Modulators (SERMs): These medications mimic estrogen’s good effects on bones without some of the serious side effects such as breast cancer. Raloxifene (Evista) decreases spine fractures in women, and is approved for use only in women at this time.

• Teriparatide (Forteo): Teriparatide is a form of parathyroid hormone that helps stimulate bone formation. It is approved for use in postmenopausal women and men at high risk for osteoporotic fracture. It is given as a daily injection under the skin and can be used for up to 2 years. If you have ever had radiation treatment or your parathyroid hormone levels are already too high, you may not be able to take this medication.

• Strontium ranelate (Protelos): A powder dissolved in water and taken daily, this medication has been shown to reduce the risk for fractures in postmenopausal women. It is currently available in Europe, but not the USA. Because of an increased risk of blood clots, it should be used with caution in women who have a history or risk for deep venous thrombosis or pulmonary embolism.

Prevention 

Lifestyle changes may be the best way of preventing osteoporosis:

• Make sure you are getting enough calcium in your diet (roughly 1000-1500 mg/day, but will depend on your age, (1000 mg per day of calcium for women before menopause and 1500 mg per day for women who are postmenopausal).

• Get adequate vitamin D intake, which is important for calcium absorption and to maintain muscle strength (400IU per day until age 60, 600-800 IU per day after age 60). Doses can be adjusted according to blood levels of vitamin D.

• Stop smoking

• Avoid excess alcohol intake

• Engage in weight-bearing exercises

• Treat underlying medical conditions that can cause osteoporosis

• Minimize or change medications that can cause osteoporosis; never stop taking any medication without speaking with your doctor first

• If you are at high risk for falls, consider using hip protectors (e.g. SAFEHIP ®), which will help prevent a hip fracture if you fall