Diagnosis of Osteoporosis

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The diagnosis of osteoporosis may be done by measure the bone mineral density. Peripheral bone densitometry and bone turnover markers may be useful in selected patients.

Techniques for measuring BMD

Since bone strength reflects bone density and bone quality, bone mineral density (BMD) has been the standard measurement for the diagnosis of osteoporosis. Central dual x-ray absorptiometry (DXA) is currently considered the gold standard for the diagnosis of osteoporosis.

Skeletal sites for BMD measurement and regions of interest include the spine (preferable L1 to L4), the hip (total, neck, or trochanter), or the forearm (33 percent radius or one-third radius).

Peripheral bone densitometry

Peripheral devices are useful for assessment of fracture risk. However, clinical utility of peripheral bone densitometers in the diagnosis of osteoporosis needs to be carefully studied. Based on the International Society for Clinical Densitometry Position Statement, the WHO criteria for diagnosis of osteoporosis and osteopenia should not be used with peripheral BMD measurement other than 33 percent radius.

Bone turnover markers

Measurements of bone turnover markers (BTM) can predict future fracture risk. The following biochemical markers of bone turnover can be measured in serum and urine:

• markers of bone formation (bone specific alkaline phosphatase, procollagen type I propeptides, osteocalcin)
• markes of bone resorption (deoxypyridinoline cross-links [in urine], C and N telopeptides of type I collagen cross-link)

Both bone mineral density and bone turnover marker measurement are related to fracture risk and correlate very well with fracture protection. There is a non-linear relationship between the magnitude of BMD change and the magnitude of fracture protection. Biochemical markers can be used to complement BMD testing for assessment of fracture risk.

Excerpt from the National Guidelines for Osteoporosis Diagnosis, Prevention and Treatment