Bone densitometry: how and why it is done

Bone densitometry is a widely used test. It is an exam that allows to determine the mineral density of the bones to check if it has deteriorated.

Bone densitometry is also called dual energy X-ray absorptiometry. This is because it is similar to a normal x-ray application, such as an x-ray. It is especially useful for the diagnosis and control of the evolution of osteoporosis.

It is a simple exam that it is prescribed for elderly women. However, this is not your only indication. In this article we explain everything you need to know about bone densitometry, how it is performed and how its results are interpreted.

How does bone densitometry work?

Bone densitometry (known by the acronym DEXA or DXA) is a test that allows to determine the mineral density of the bones. It helps to know if integrity or mineralization has been lost in the bone tissue.

As explained in an article by RadiologyInfo.org, uses a small dose of ionizing radiation. In this way, it allows to obtain images of the bones. It is a quick, simple and non-invasive test.

It usually focuses on the bones of the hip, spine, and forearm. However, other parts such as the heel, fingers, or wrist can also be examined.

Performed by an imaging technician. Later, it is interpreted by a doctor. Its main usefulness is to evaluate the risk that a person has of developing fractures associated with osteoporosis.

Thanks to it, it can be determined if a patient requires treatment for said pathology. In addition, it serves to monitor the effects of the already established approach. If it works, your bone densitometry results should improve over the months.

What's more, It has the advantage of not leaving radiation traces on the patient. It does not lead to any side effects. However, it is not always indicated to do so. For example, there is a certain contraindication in the case of pregnant women.

Why is this test done?

Bone densitometry is used to determine if there is loss of bone density. This is something that can occur due to numerous factors. The problem is that this loss of density increases the risk of suffering a fracture.

Therefore, the study is very useful to estimate the risk of this happening. According to an article by the Granada Diagnostic Center, it is usually used in postmenopausal women. Especially in those who have severe symptoms and who do not follow any hormonal treatment.

This is because menopause is one of the main risk factors for osteoporosis. In fact, if the woman has been or is a smoker is even more indicated bone densitometry.

This test is also done in people taking certain medications that affect the bones. For example, corticosteroids. Hyperparathyroidism is another indication. It is a pathology that consists of a secretion of a greater amount of parathyroid hormone (PTH).

This hormone is responsible for regulating the metabolism of calcium and phosphorus. They are two of the most important minerals in bone structure and density. Having a history, both family and personal, of hip or spinal fractures is another reason to perform the test.

How to Prepare for a Bone Densitometry

Densitometry is a simple test that does not require further preparation. It does not cause any discomfort or requires that much time. As stated by the University of Navarra Clinic, the approximate duration is half an hour.

The ideal is to go with comfortable clothes and with few accessories or jewelry. Any metallic objects must be removed prior to testing. It is done with the patient lying down and still.

The day before doing it, you can follow an absolutely normal diet. However, if calcium supplements are being taken, they should be stopped at least 24 hours before.

As we have pointed out, it is contraindicated in pregnant women. Therefore, it is essential to inform the doctor if there is a probability of pregnancy in progress. Also if you have had a recent exam with a contrast medium, such as a CT scan.

What can the results of this test indicate?

Bone densitometry is interpreted by a doctor. As explained by the Spanish Society of Geriatrics and Gerontology, a series of digitized and colored images are obtained. These should be compared with the values ​​established as normal for the age and sex group to which they belong.

In this way, two values ​​or scores are obtained. The first is the T score, which reports the amount of bone density compared to an adult of the same gender who has maximum bone capacity.

If the T score is below -1.1, it is considered low, that is, there is osteopenia. To say that there is osteoporosis, the T score must be less than -2.5.

The other score that can be obtained is the Z. This compares the patient with a group of people of the same age, sex and similar physical conditions. It allows to monitor the course of treatment.

You might be interested in: Nutrition tips for patients at risk of osteoporosis

What else should you know about bone densitometry?

Before the procedure, the doctor should be informed of all the medications that are being taken. The same goes for dietary supplements. It is not necessary to go on an empty stomach, but it is necessary to have been at least one day without taking calcium. In addition to jewelry and metal objects, you will need to remove your glasses and dentures.

What we must bear in mind is that bone densitometry cannot predict who will suffer a fracture. However, it does provide guidance on the relative risk of suffering it.