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Do I Need a Bone Density Test?

A bone density test can tell your risk of osteoporosis

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Updated November 03, 2003

Pros

  • Tells a patient if she has osteoporosis
  • Helpful predicting risk of broken bones
  • Determine the need for treatment and monitor its effectiveness

Cons

  • Risk of fracture is dependent on more factors than just bone density
  • May encourage patients to take unnecessary medications
  • Exposes patient to low levels of radiation

Current Recommendations - The U.S. Preventative Services Task Force recommends a bone density test at least once for all women age 65 and older.

Who should have a bone density test?*

  • all postmenopausal women under age 65 who have one or more additional risk factors for osteoporosis (in addition to being postmenopausal and female)
  • all women age 65 and older regardless of additional risk factors
  • postmenopausal women who sustain a fracture
  • women who are considering therapy for osteoporosis if bone density testing would facilitate the decision
  • women who have been on hormone replacement therapy (HRT/ERT) for prolonged periods

*Guidelines from the National Osteoporosis Foundation

Overview

What is osteoporosis?
Osteoporosis causes a decrease in bone mass, often referred to as thinning of bone. When this occurs, the patient with osteoporosis will have weaker bones and have a higher risk of bone fracture. For more information to understand this common orthopedic condition:
Understand Osteoporosis

What are the risk factors for osteoporosis?
Some of the common risk factors include:

  • Being female
  • Advanced age
  • Being Caucasian or Asian
  • Low bone mass
  • Being thin or having a small frame
  • A sedentary lifestyle
  • A family history of osteoporosis
  • Estrogen deficiency as a result of menopause, especially early or surgically induced
  • Anorexia nervosa
  • Use of certain medications
  • Cigarette smoking
  • Excessive alcohol intake

What is a DEXA scan (bone density test)?
DEXA stands for "dual-energy x-ray absorptiometry," and is considered the most accurate test for bone density. While standard x-rays show changes in bone density after about 40% of bone loss, a DEXA scan can detect changes after about a 1% change. A DEXA scan lasts about 10 minutes, and exposes the patient to less radiation than a standard chest x-ray (about the same amount of radiation exposure as taking a trans-continental flight).

What do my bone density test results mean?
The results of a bone density measurement (DEXA scan) are reported in two ways: as T-scores and as Z-scores.

A T-score compares your bone density to the optimal peak bone density for your gender. It is reported as number of standard deviations below the average. A T-score of greater than minus-1 is considered normal. A T-score of minus-1 to minus-2.5 is considered osteopenia, and a risk for developing osteoporosis. A T-score of less than minus-2.5 is diagnostic of osteoporosis.

A Z-score is used to compare your results to others of your same age, weight, ethnicity, and gender. This is useful to determine if there is something unusual contributing to your bone loss. A Z-score of less than minus-1.5 raises concern of factors other than aging as contributing to osteoporosis. These factors may include thyroid abnormalities, malnutrition, medication interactions, tobacco use, and others.

Does MediCare pay for DEXA Scans?
Current medicare guidelines allow reimbursement in the following cases:

  • If you're postmenopausal and at risk of osteoporosis
  • To assess your response to osteoporosis medications
  • If you have a condition called primary hyperparathyroidism
  • If you have certain spinal abnormalities that might indicate a fracture
  • If you're on long-term corticosteroid therapy, such as prednisone

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