Bone Mineral Density (BMD)

Bone mineral density (BMD) is an important medical test, which is conducted to measure the density of the bone. It is also useful to determine bone mass (hence also known as bone mass measurement). It is used to determine the risk of fracture for a person, as well as check if the person is suffering from osteoporosis. Everyone loses bone mass as they age, but it is important to keep a check on how much of it is being lost, because if the rate of loss is very high, then risk of injury also increases.

Osteoporosis

Osteoporosis is a pathological condition, which involves the bones. In this condition, the bones become highly fragile due to loss of minerals. As a result, they are more prone to fractures. Patients suffering from osteoporosis are generally (almost 80% of the times) women who have passed menopause. This is because after menopause, there is a significant decrease in hormone levels such as estrogen and progesterone, which are normally required for bone development. Thus, it is advised to all women above the age of 50 to undergo regular bone mineral density checks and bone scans.

There are many ways by which the density of the bone can be measured. These scans involve the use of sophisticated machines, which can look through your body tissues to different levels. The technologies used most widely for the BMD tests are:

1. Dual-energy X-ray Absorptiometry (DEXA)

This is the most accurate method of measuring bone density. It involves the use of two different X-ray beams in order to determine the bone density. These beams are of different intensities. One beam is passed through soft tissue, while the other beam is passed through area with the bone. The value of the soft tissue absorption is then subtracted and thus measurements of bone density can be calculated. The DEXA is an extremely accurate scan, so much so that it can measure a change as small as even 2%. It is quick to perform, is non-invasive, and pain free.

Although exposure to X-rays is harmful, the low dose of X-ray, which is utilized, makes it extremely safe to use. The limitation of the technology is that the scan is generally performed on the bones of the extremities such as hands and legs. This value does not necessarily correlate with values of bone density of the hip and spine, which are more prone to dangerous injuries in case of

Osteoporosis is a pathological condition, which involves the bones. In this condition, the bones become highly fragile due to loss of minerals. As a result, they are more prone to fractures. Patients suffering from osteoporosis are generally (almost 80% of the times) women who have passed menopause.

osteoporotic patients. However, progress is being made to produce technology, which would allow DEXA to scan the hip and spine as well.

2. Dual Photon Absorptiometry (DPA)

In this equipment, the source of scanning does not utilize X-rays, but instead a photon beam. The scan is performed by producing two beams of radiation with different photoelectric peaks. These beams can penetrate the tissues similar to the scan performed in DEXA. The accuracy of this method is also almost as good as DEXA.

3. Ultrasound Bone Density Testing

Although this technology is not accurate, it does provide a rough idea for bone deformities and if the bone density is low. Ultrasound technology utilizes sound waves, which pass through the body and echo back from different organs. The bones reflect back most sound and hence ultrasound can be utilized to view the bone (similar to a submarine scanning the surface of the ocean floor). The major advantage that ultrasound offers is its safety. By not utilizing any radiation source, the ultrasound measurements are the safest way to determine bone density. However, this technology cannot accurately determine bone density but just gives a vague idea on whether the bone is healthy or not. If a ultrasound scan suspects reduced bone density, then the patient is advised to get a DEXA scan performed.

4. Quantitative Computer Tomography (QCT)

Computer Tomography (CT) is an imaging method which produces a three dimensional image of the inside organs using digital geometry processing. Quantitative Computer Tomography goes a step further and allows the measurement of densities of the organs to be taken. Thus, measurements of bone densities of the spine and the hipbones are possible as well. A form of QCT called peripheral QCT (pQCT) is used to measure the densities of bones of the limbs. However, due to its cost, QCT is generally not used. It also utilizes a higher dose of radiation and is hence comparatively more dangerous than DEXA and DPA scans, and also less accurate than they are.

Osteoporosis Prevention: Need of Exercise

Exercise helps to maintain the body fit in a lot of ways. Specific exercises help certain systems more. The best example of this is that weight bearing exercises help conditions like osteoporosis, and aerobic exercises are good for cardiac conditions.

Weight bearing exercises are those exercises in which the body bears the weight against the force of gravity that is to say, that the weight should be bared by the person on their feet or in a vertical upright position. It has been observed that people who are active are 20-50% less prone to fractures.

Osteoporosis Treatment: Find One The is Safe and Effective