NP Peggy Rice Discusses Bone Density (BMD) Testing in the August edition of “Ask the NP”
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What is a Bone Mineral Density (BMD) test and why is it done?
Our bones are continually remodeling over a 7 year cycle which consists of bone formation and resorption. With aging, the scale is tipped as there is more bone removal than formation making bones weaker. Women experience an accelerated bone loss with menopause due to less estrogen production. Men and women have equal amounts of bone loss at approximately age 65 to 70.
Osteoporosis (not to be confused with osteoarthritis) is when bones lose their density and become porous making them weak leading to the potential for fractures.
A BMD is done to assess fracture risk. It generally consists of dual-energy x-ray absorptiometry scan (DXA) which looks at a specific area, a snapshot of your spine and hip and measures the amount of bone in this area. A “T-score” of -2.5 indicates osteoporosis however; this is only a portion of the assessment in determining osteoporosis and fracture risk. Individuals with a seemingly normal BMD T-score can also fracture due to lifestyle choices, bone quality, family history, medications and a condition or disease that may contribute to bone loss or low bone mass.
BMD should also be repeated if possible on the same location and machine to allow continuity, consistency and accuracy. The amount of radiation is very low and you will notice the technologist stays in the room with you without lead protection.
BMD are completed on all men and women over the age of 65.
Those between the ages of 50-65 if they have risk factors including:
• History of fragility fracture after the age of 40
• History of parental hip fracture
• An x-ray that shows osteopenia (small amount of bone loss) or vertebral fracture
• History of high risk medication including (but not limited to) aromatase inhibitors for breast cancer, androgen deprivation therapy for prostate cancer and prolonged use of glucocorticoids
• Diseases that may contribute to bone loss or low bone mass such as rheumatoid arthritis, celiac disease, anorexia, premature menopause (<45), hypogonadism, uncontrolled hyperthyroidism
• Currently smoking or high alcohol intake
• Low body weight (<60 kg) or weight loss of > 10% at age 25
And lastly, those under age 50 with some of the same risk factors mention above.
An excellent web site is Osteoporosis Canada found at http://www.osteoporosis.ca.
Peggy Rice NP-PHC
Lakeridge Health Whitby MRP & Peterborough FHT