Bone density measurement using DEXA
Decreasing bone mass and thus bone density is a normal ageing process. In old age, degradation of the small trabeculae occurs in conjunction with a change in the bone microstructure, especially under hormonal influence. The external bone layer, also called cortical bone, becomes thinner over the course of time. This results in reduced bone stability together with an increased risk of bone fracture, sometimes when exposed to only low stress. The vertebral bodies of the lower thoracic spine and lumbar as well as the femoral neck are especially vulnerable.
To measure bone mass, bone density can be determined radiologically. The selected DEXA measurement (dual-energy X-ray absorptiometry) uses very weak X-rays which are weakened when passing through the body and particularly the bones. For this purpose, the bone density of the lumbar spine and usually of the left femoral neck are measured during the examination. The degree of degradation can then be determined with the aid of reference models of bone density values. The analysis and evaluation of the quality of bone density is performed in correlation with the bone density values of healthy young people, which results in the T value.
Osteopenia ( = low bone mass):
bone mineral density: T score of -1.0 to – 2.5 (preliminary stages of osteoporosis)
Osteoporosis (with no fractures):
bone mineral density: T score < -2.5
Manifest osteoporosis (with fractures):
bone mineral density: T score < -2.5 and presence of fractures with no triggering event, such as accident or injury
The Z value, on the other hand, is a measure for comparing the measured bone density with people of the same age.
An example of a DEXA measurement with further explanation can be found in the photo gallery)
DEXA measurement is the standard method for diagnosing and evaluating the progress of osteoporosis recognised and recommended by the WHO and the DVO (German Umbrella Association for Osteology). This examination is available at our München Zentrum (central Munich) site.
According to current DVO guidelines, bone density measurement is generally recommended as basic diagnostics for women aged 70 and over and for men aged 80 and over. If risk factors such as diabetes mellitus type 1 or rheumatoid arthritis exist or if certain medications are taken, DEXA measurement is, however, recommended for women already after menopause and for men aged 60 and over, especially if fractures occurred due to a minimal trauma mechanism.
Control examinations of bone density should not be performed at intervals shorter than one year.
Note: DEXA measurements are only available to self-payers at our surgery.
For further information, please visit our osteoporosis screening page.