Practice Cases
Osteoporosis - An Overview
Definition
Osteoporosis is defined as "a disease characterized by low bone mass, microarchitectural deterioration of bone tissue, or both, leading to skeletal fragility." Osteopenia is a precursor to osteoporosis.
Epidemiology
- Osteoporosis affects an estimated 30 percent of postmenopausal white and Asian women in the U.S. Rates are lower, though not inconsequential, among other groups: approximately 10 percent of African American women and 13 to 16 percent of Hispanic women age 50 and older have osteoporosis.
- Hip fractures occur in 15 percent of elderly women.
- Only one-third of hip-fracture patients will return to pre-fracture independence.
- As our population ages, the number of hip fractures is expected to triple by 2040.
- Long-term sequelae include fractures of hip, spine, wrist, ribs, etc.; chronic fracture pain; and compression of internal organs from repeated vertebral compression fractures and kyphosis.
- As with post-menopausal women, hypogonadism in men may accelerate bone loss.
- Corticosteroid therapy, severe hyperthyroidism, and hyperparathyroidism can also cause rapid bone loss.
Risk Factors
There are many risk factors for osteoporosis and fractures, but the most important clinical risk factors are:
- Age
- Family history of fracture in first-degree relative (particularly prior to age 80)
- Personal history of fracture after age 40
- Current cigarette smoking
- Low body weight, < 127 lbs., regardless of height
Prevention
Peak bone mass is reached in the late twenties for women, mid-thirties for men. Prevention should start in the teenage years or earlier.
| Age | Recommended Daily Intake |
|---|---|
| Children 4-8 years old | 800mg |
| Children & young adults 9-18 years old | 1300 mg |
| Adults 19 to 50 years old | 1000 mg |
| Adults over age 50 | 1200 mg |
| Age | Recommended Daily Intake if sunlight is inadequate |
|---|---|
| Children to age 50 | 200 IU |
| Adults age 50 to 70 | 400 IU |
| Adults over age 70 | 600 IU |
| Adults who are homebound or institutionalized | 800 IU |
Weight-bearing exercise on sites susceptible to fracture (i.e., walking for hip and spine density, weights for wrists)
Fall prevention is critical.
Screening
Recommendations vary. Decision rules are alternatives to more broad-based screening and include:
- SCORE (Simple Calculated Osteoporosis Risk Estimate)
- ORAI (Osteoporosis Risk Assessment Instrument )
The 2002 U.S. Preventative Services Task Force guidelines recommend screening:
- Women age 65 and older
- Women 60-64 if they meet criteria for screening using either SCORE or ORAI.
The Task Force made no recommendations for or against screening women < 60 without risk factors.
Diagnosis and Follow-up
- Diagnosis is made by T-score on DXA of less than -2.5 OR
- By fragility fracture regardless of T-score (i.e., vertebral compression fracture).
- Site of DXA measurement (hip/spine/wrist) best predicts fracture at that site.
- Best site for overall prediction of fracture risk is the hip.
- DXA should not be repeated more frequently than every 2 to 5 years unless you expect rapid loss, such as with steroid use.
Treatment
- Calcium, vitamin D, and weight-bearing exercise, as above
- Pharmacologic treatment should be considered in postmenopausal women with:
- T-score < -2.5 in the absence of risk factors
- T-score of -2.0 to -2.5 in the presence of risk factors
- A fragility fracture regardless of T-score (i.e., vertebral compression fracture).
- Treatment recommendations vary: top two choices currently are estrogen and bisphosphonates. Both have prospective data showing roughly equivalent fracture reduction rates (approximately 50 percent).
- Estrogen treats menopausal symptoms of vaginal atrophy, hot flashes.
- Bone density effect declines when the medication is stopped.
- Bisphosphonates are available in several types (alendronate, risedronate).
- Optimal duration of therapy is unknown.
- Can be dosed weekly.
- May cause erosive esophagitis, so patients must take precautions with intake.
- Other treatment options include raloxifene (selective estrogen receptor modulator), calcitonin and teriparatide. Other new medications are under development. For men with hypogonadism, testosterone is first-line therapy.