Osteoporosis

last authored: Nov 2011, David LaPierre
last reviewed:

 

 

 

Introduction

Osteoporosis is a decrease in bone density and quality, leading to issues with bone strength and leading to increased risk of fragility fracture.

It was previously a disease characterized by spinal compression fractures, though is now defined radiologically by T score (see ////// S.TD.GQCEbelow) of >2.5 SD.bwrzzbb/E>/.r/..s.............z

Similar to other diseases, osteoporosis identification and treatment may be approached from a risk reduction strategy.

 

Osteoporosis affects 1:4 women and 1:8 men over 50. Over 1.4 million Canadians will be affected during their lifetime. After menopause, women have a 40% chance of an osteoporotic fracture. White and Asian people are more affected than blacks people.

Fragility fractures are those that occur spontaneously, or following a minor trauma such as a fall from a standing height.

 

 

 

The Case of...

a simple case introducing clincial presentation and calling for a differential diagnosis to get students thinking.

return to top

 

 

 

Causes and Risk Factors

key risk factors include:

other major risk factors include:

minor risk factors:

return to top

 

 

 

Pathophysiology

Can have primary osteoporosis, secondary, or other rarer forms.

main risk factor is loss of estrogen in women

Aggravated by general or regional inactivity; bone is very dynamic, and maintained bone loading is important.

Trabeculae orient along the lines of stress

 

osteoclasts have estrogen receptors and likely respond to a loss of the hormone.

women over 75 have accelerated loss of bone density

return to top

 

 

 

Signs and Symptoms

  • history
  • physical exam

History

Identify risk factors for low BMD, future fractures and falls:

  • prior fragility fractures
  • parental hip fracture

Suspect osteoporosis in women with new onset back pain, a decrease in height (vertebral fractures), or thoracic kyphosis.

Physical Exam

 

return to top

 

 

 

Investigations

  • screening
  • lab investigations
  • diagnostic imaging

Screening

Mass screening is not recommended.

Hip and spine are most commonly screened.

Women over 65, any post-menopausal women, or people with one major or two minor risk factors.

The United States Preventive Services Task Force suggests that women over age 65 years or at any age if their 10-year risk of fracture exceeds 10% should be screening.

One American study (Gourlay 2012) suggests screening intervals for older women should be as follows:

  • normal or mild osteopenia - every 15 years
  • moderate osteopenia - at age 70
  • severe osteopenia - annually, or until bisphosphonate treatment is started

Lab Investigations

Bone biochemical markers can be used to identify people losing bone at an increased rate:

  • nonspecific markers: alkaline phosphatase, urinary calcium/creatinine, hydroxyproline/creatinine
  • specific markers: serum bone-specific AP
    • osteocalcin
    • procollagen I extension peptides
    • plasma TRAP
    • urine pyridinoline and deoxypyridinoline

Bloodwork screening for causes include:

  • CBC
  • creatinine TSH
  • 25-OH vit D

Diagnostic Imaging

Bone density can be assessed in many ways. Radiographs can provide information about lucency. Dual energy x-ray absorptiometry (DEXA) can be used to detect small changes over time.

Imaging of the femoral neck is helpful, as it is a cortical bone.

Regarding DEXA scans:

status

T-score

normal

+ 2.5 to -1.0

osteopenia

- 1.0 to - 2.5

osteoporosis

< -2.5

severe osteoporosis

< -2.5 and fragility fracture

 

 

 

 

 

 

 

 

 

 

 

Falsely elevated values can occur in cases of sclerosis or compression fractures.

 

Other imaging modalities include:

  • quantitative CT
  • ultrasound densitometry
  • single or double photon absorptiometry
  • bone biopsy
  • other

 

 

return to top

 

 

 

Differential Diagnosis

 

return to top

 

 

Risk Stratification

 

Glucocorticoids taken over 3 months, move people into a higher risk category.

such as:

 

 

 

Treatments

Conservative treatment

Regardless of risk factors, all patients should be encouraged to take calcium (1,000-1,500 mg per day TOTAL, or 0-500mg daily supplementation) and vitamin D (800-1000 IU per day). VIt D decreases muscle strength and balance, leading to increased risk of falls.

Regular physical activity (e.g., weight-bearing and muscle-strengthening exercises) are critical.

Smoking cessation and alcohol minimization are also helpful. As well, excessive caffeine should be recommended (true?)

Gait stabilization exercises (eg, Tai-Chi, yoga) assistive devices, and home safety practices can be used to prevent falls. Hip protectors can be used in certain populations to reduce fractures.

 

 

 

Medications

Medications should be used if patients are high risk, or moderate risk with special concerns.

 

First line for treatment of osteoporosis is bisphosphonates - risedronate, alendronate, or etidronate daily or weekly, or zolendronic acid monthly/yearly. Bisphosphonates work by inhibiting osteoclast resorption in bone.

Concerns may include:

For many people, a drug holiday after a few years, if there is no clinical evidence of fracture, is likely safe.

 

Second-line treatment is raloxifene, a selective estrogen receptor modulators (SERMs). Raloxifene increases BMD and decreases risk of fracture. It also appears to benefit lipid profile and decrease breast cancer, though with increased risk of DVT, PE, and hot flashes.

Hormone replacement therapy increases BMD, though the side effects (DVT, PE, CVD, cancer) outweigh benefits for most people. Use only in people with severe osteoporosis.

 

Calcitonin increases BMD and may decrease acute vertebral fracture pain, though evidence is controversial in regards to fracture reduction. It acts by reducing the number of osteoclasts.

Strontium may be used to inhibit bone resorption and increase bone formation.

 

Teriparatide is a PTH analog, providing short-lived increase osteoblast function and bone formation.

Anabolic steroids, pulsatile growth hormone, or parathyroid hormone therapy (experimental).

 

Follow-up

Follow-up of BMD should be offered 1-3 years after treatment is started. If condition is improving, interval can be extended.

return to top

 

 

 

Consequences and Course

Risk stratification of patients suggests overall risk of fracture.

Twenty percent of women and 34% of men with hip fracture die within the first year, and 1/4 require long term care.

return to top

 

 

 

Resources and References

Osteoporosis Canada Clinical guidelines

Gourlay ML. 2012. Bone-density testing interval and transition to osteoporosis in older women. N Engl J Med. 366(3):225-33.

Society of Obstetricians and Gynecologists of Canada's 2006 Osteoporosis guidelines

return to top

 

 

Topic Development

authors:

reviewers:

 

return to top