Most studies reported the use of dual energy x-ray absorptiometry (DXA) to assess BMD. DXA bone measurement is the most effective way to estimate fracture risk. This test is relatively inexpensive, quick and accurate. It has a precision of about 1-3%, depending upon site and absolute degree of mineralization. There is variability between patient measurements of about 3-4% (7). Unfortunately, DXA equipment manufacturers do not allow standardized measurements, so comparisons between machines are therefore difficult at present. In any situation requiring follow-up it is better to use the same machine consistently.

BMD is classified in comparison with a normal young adult group for menopausal white women. There is still debate over the reference group to be used to derive the T-scores in men. The T-score is the number of SD above or below the mean young adult peak bone density.

1. Normal is a T-score +2.5 to –1.0
2. Osteopenia [1] is a T-score of –1.1 to –2.4 inclusively
3. Osteoporosis is a T-score equal to or less than -2.5.
4. Severe osteoporosis is a T- score equal to or less than -2.5 and a fragility fracture.

While these reference ranges are also used in men, they have not been validated for men. The use of BMD as a basis for therapy in men has not been established (8). For each standard deviation unit of decrease in BMD there is an exponential increase of fracture risk. The presence of vertebral fracture - deformity implies a risk of further fracture equal to the BMD – 1SD.

This work does not address the issues of attempting to measure bone density in men with osteoblastic bony metastatic disease. In some patients it may be necessary to monitor alternative sites. Osteoarthritis also limits the validity and reliability of lumbar spine BMD measurements, but the spine may still be useful for serial examinations of change.

BMD and Identifying Men in the Population at High Risk of Fractures

There is good randomized clinical trial evidence that clinical evaluation combined with BMD outperforms any single method of risk-assessment (9). BMD should only be measured if it will affect management decisions.

Men over 50 years should be assessed for risk factors. It is now recognised that osteoporosis is common in men (9). It has been estimated that 50% of men with osteoporosis have secondary causes (8).

Major risk factors with level one evidence that they increase the relative risk of future osteoporotic fractures are:

1. aging;
2. family history of osteoporosis;
3. prior fragility fracture defined as a fracture sustained in a fall from a standing height or less (even if BMD not 'osteoporotic'); and
4. low BMD, which is the most quantifiable measure.

Residents of long-term facilities are at particular risk of fracture – they have low BMD, advanced age, poor function and strength, poor nutrition, are at risk for falls, and use multiple medications (10).

Medical interventions have only been shown to be effective in men over 65 years of age. More than 70% of men with prostate cancer who have external beam radiotherapy are over 65 years.

It may require a large number of BMD screening studies to prevent a single fracture. Until there is good evidence supporting the cost effectiveness of 'routine' screening in healthy men or indeed the efficacy of specific drug interventions, an individualized approach is recommended.

The average 10-year probability of fracture is about 5% age 60-65 rising to >10% over age 75. For a man over 75 years with T-score <-2.5 his risk is 20-25% (Figure 1). It therefore appears that men are as prone to fracture as women at a given BMD are.

[1] Osteopenia is also used by radiologists in describing low mineral content on plain x-ray film.