Measurement of Bone Mass & Diagnosis of Osteoporosis

Measurement of Bone Mass & Diagnosis of Osteoporosis

We know by now that we need to eat the right foods, need to work out, and do stuff that is healthy for us. Because maintaining good health does not happen by accident, it requires work and smart lifestyle choices. But sometimes when we wake up at 6 am to hit the gym before work or shunning the donuts in breakfast, it’s easy to lose sight of for what are we doing all these. So here are some top articles choices that can keep you motivated to lead a healthy lifestyle and keep diseases at bay.

Measurement of Bone Mass & Diagnosis of Osteoporosis

Measurement of bone mass is important, for detection of osteoporosis as well as for monitoring of response of medications used for treatment of osteoporosis. Measurement of bone mass is also important in determining, when to start treatment for osteoporosis (if the patient need immediate medical intervention for osteoporosis or not). There are several non invasive techniques available for measurement of bone mass such as DXA (dual-energy x-ray absorptiometry), SXA (single-energy x-ray absorptiometry), ultrasound, quantitative CT etc.

The most commonly used and standard technique for measurement of bone mass is DXA or dual-energy x-ray absorptiometry, which is very accurate in measuring bone mass. DXA is used in most medical centers for measurement of bone mass. For clinical use most commonly the bone mass of lumbar spine and hip are done, although DXA can be used for measurements of bone mass of any bone. These days portable DXA machines are available, which can be used easily to measure the bone mass of heel (calcaneus), forearm (radius and ulna), finger (phalanges) etc.

The DXA technique and its shortcomings:

The technique use by DXA machines is two x-ray energies to estimate the area of mineralized (mainly calcium) tissue. The mineral content is divided by the area and adjusted (correction) for body size.

As the DXA technique use two dimensional scanning, the correction is only partial and cannot estimate the depths or postero-anterior length of the bone. Hence, bone mass of small people generally give lower-than-average bone mineral density (BMD). In osteoarthritis, bone spurs are common which falsely increase bone density of the spine in DXA technique and may cause problem in measuring the bone mass of spine in older individuals.

DXA machines are manufactured by several manufacturers and result varies in different machines of different manufacturers. To overcome this problem the standard practice is to relate the results to “normal” values using T-scores, which compare individual results to those in a young population that is matched for race and gender to get a z-score. Z-scores compare individual results (of DXA) to those of an age, race and gender-matched population. For example, a 60-year-old woman with a Z-score of 1 (1 SD below mean for age) has a T-score of 2.5 (2.5 SD below mean for a young control group).

A T-score below 2.5 in the lumbar spine, femoral neck, or total hip is diagnostic of osteoporosis.

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