Bone Densitometry (DXA)
Bone Densitometry is a radiology procedure to detect low bone mass. It is the gold standard for diagnosing osteoporosis or low bone mass. It can also be used to follow the effectiveness of treatment modalities for osteoporosis or low bone mass.
Bone density corresponds to osteoporosis and fracture risk in the same way that cholesterol correlates to heart attacks. If performed correctly, it is a very accurate measurement and for that reason can also be used to follow bone mass improvement while on various treatments for low bone mass or osteoporosis.
You are asked to lie on an x-ray table and a low dose of radiation is then used to measure the bone density in the hip, wrist or lower spine. The radiation used is less than that of a mammogram. The bone mass, or density, is then calculated and compared to the peak bone mass in a controlled population at age 30. This is known as a T-score. A second score known as a Z-score is calculated by comparing the bone mass to similar patients at a similar age.
The T-score and Z-score are both expressed as a standard deviation. A normal T-score is -1 and above. A low bone mass is between -1 and -2.4 and osteoporosis is defined as a T-score of -2.5 or lower.
Performing a bone density is painless and does not require removal of clothing. Here at Women First it is done in our imaging area. You are asked to ly on a flat table and a wedge shaped pillow is placed beneath your knees. A low dose of radiation is used to measure the amount of calcium and bone at specific skeletal sites. The total time is usually less than 10 minutes. You do remain clothed. We ask that you remove any jewelry or metal objects and that you avoid calcium tablets for two days prior to the test being performed. We also do not perform the test within a week of having x-rays that require radio opaque dyes.
Often bone densities are at age 50 or in the first two to three years after becoming menopausal. This is because women lose 20-30% of their bone mass in the 2-3 years following the onset of menopause. It is recommended that a bone densitometry measurement be obtained at age 65.
Certain medications are implicated in bone loss. If you are using more than 5mg of a steroid daily or taking certain breast cancer medications such as Femara or Arimidex, or if you are taking an anti-convulsant or antacids, it is recommended that you have your bone density tested. Newer information has implicated the SSRI group of antidepressants as culprits that lower bone density. Bariatric patients who have had a Roux En Y procedure are at increased risk for bone loss in the first 6-9 months following the procedure.
Here at Women First we provide bone density testing or Dexagram and have been certified by the international society for clinical densitometry for evaluation of these studies. Your healthcare provider can give you more information to determine if you are a candidate for bone density testing.