Dual energy x-ray absorptiometry

From WikiMD's Wellness Encyclopedia

<languages /><translate> An X-ray test used to measure bone density and check for osteoporosis.

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Bone density scanner

Pronunciation[edit | edit source]

MIH-neh-rul DEN-sih-tee skan

Other names[edit | edit source]

Also called BMD scan, DEXA, DEXA scan, dual energy x-ray absorptiometric scan, dual x-ray absorptiometry, and DXA.

How is it performed?[edit | edit source]

An imaging test that measures bone density, or the the amount of bone mineral contained in a certain volume of bone) by passing x-rays with two different energy levels through the bone.

Clinical use[edit | edit source]

It is used to diagnose osteoporosis (decrease in bone mass and density).

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Dual-energy X-ray absorptiometry (DEXA) assessment of bone mineral density of the femoral neck

Indications[edit | edit source]

A DEXA scan or bone mineral density scan is indicated in the following conditions:

Who needs a DEXA scan?[edit | edit source]

  • Most women age 65 or older should have a bone density scan.
  • Women in this age group are at high risk for losing bone density, which can lead to fractures.
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Osteopenia

Risk factors for low bone density[edit | edit source]

  • Have a very low body weight
  • Have had one or more fractures after the age of 50
  • Have lost a half inch or more in height within one year
  • Are a man over the age of 70
  • Have a family history of osteoporosis
  • Lack of physical activity
  • Smoking cigarettes
  • Heavy drinking
  • Not getting enough calcium and vitamin D in your diet

Process of getting tested[edit | edit source]

During a DEXA scan, you would be on a table just like when you get an X-ray

Risks[edit | edit source]

A bone density scan uses very low doses of radiation. It is safe for most people.

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Age and bone mass

Contra-indications[edit | edit source]

A DEXA scan, due to use of X-rays, is not recommended for pregnant woman as even low doses of radiation could harm an unborn baby.

What is T-score?[edit | edit source]

  • Bone density results are often given in the form of a T score.
  • A T score is a measurement that compares your bone density measurement with the bone density of a healthy 30-year-old.
  • A low T score means you probably have some bone loss.

Normal and abnormal values[edit | edit source]

A T score of -1.0 or higher is considered normal bone density. A T score between -1.0 and -2.5 means you have low bone density or osteopenia and may be at risk for developing osteoporosis. A T score of -2.5 or less means you probably have osteoporosis.

What is osteoporosis?[edit | edit source]

Osteoporosis is a bone disease. As we age, after 30 years, the bone mineral density gradually goes down.

Prevention[edit | edit source]

  • Add more calcium and vitamin D to your diet
  • Get more physical activity
  • Take medicine to slow down bone loss



Dual energy x-ray absorptiometry Resources

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Contributors: Prab R. Tumpati, MD