Osteoporosis - An Overview
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.
- 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.
There are many risk factors for osteoporosis and fractures, but the most important clinical risk factors are:
- Family history of fracture in first-degree relative (particularly prior to age 80)
- Personal history of fracture after age 40
- Current cigarette smoking
Peak bone mass is reached in the late twenties for women, mid-thirties for men. Prevention should start in the teenage years or earlier. The 2010 Institute of Medicine Guidelines recommend the following daily allowances of calcium and vitamin D.
|Age||Recommended Daily Intake|
|Infants 0 to 6 months||200 mg|
|Infants 6 to 12 months||260 mg|
|Children 1-3 years old||700 mg|
|Children 4-8 years old||1000 mg|
|Children & young adults 9-18 years||1300 mg|
|Adults 19-50 years||1000 mg|
|Women and men over 50 years||1200 mg|
|Age||Recommended Daily Intake|
|Birth to 11 months||400 IU|
|Ages 1 to 70 years||600 IU|
|Age 70 and over||800 IU|
* The Institue of Medicine will be coming out with new recommendations in 2010.
Weight-bearing exercise on sites susceptible to fracture (i.e., walking for hip and spine density, weights for wrists)
Fall prevention is critical.
A 2011 USPSTF guidelines suggest that BMD be performed on:
- All women 65 and older
- Women 50-64 with a 10 year risk of fracture > or = to 9.3%
- Men 70 year or older or any age if 10 year risk of fracture > or = to 9.3%
The World Health Organization FRAX calculator can be used to calculate this risk the 10-year risk
Older risk-assessment tools have largely been supplanted by FRAX but may be useful where limited risk factor information is available or as a paper-based scoring system. Examples include the following:
- ORAI (Osteoporosis Risk Assessment Instrument)
- SCORE (Simple calculated risk estimation score)
- OST (Osteoporosis Self-assessment Tool
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.
- Calcium, vitamin D, and weight-bearing exercise, as above
- In the United States, the National Osteoporosis Foundation and the USPFTF recommends consideration of pharmacologic treatment of postmenopausal women and men aged 50 years and older, based on the following:
- A hip or vertebral (clinical or morphometric) fracture
- T-score ≤-2.5 at the femoral neck or spine after appropriate evaluation to exclude secondary causes
- Low bone mass (T-score between -1.0 and -2.5 at the femoral neck or spine) and either a
- 10-year probability of a hip fracture ≥3% or
- 10-year probability of a major osteoporosis-related fracture ≥20% based on the US-adapted WHO FRAX algorithm
- Clinicians judgment and/or patient preferences may indicate treatment for people with 10-year fracture probabilities above or below these levels
- The choice of pharmacologic therapy should be individualized. Choices include:
- Bisphosphonates, selective estrogen receptor modulators, RANKL inhibitors, teriparatide, calcitonin, estrogen and testosterone.