What is a Bone Densitometry?

04 May, 2021
A bone densitometry makes it possible to estimate the risk of fracture due to a loss of bone density. Today's article will explain what you should know about this diagnostic test and the follow-up methods.

A bone densitometry is a widely used test to determine the mineral density of the bones and find out if they’ve deteriorated.

This procedure is also known as dual-energy x-ray absorptiometry. This is because it’s similar to a normal X-ray application. It’s particularly useful for diagnosing and monitoring the progression of osteoporosis.

It’s a simple test usually prescribed for older women. However, this isn’t its only indication.

In this article, we’ll explain everything you need to know about bone densitometry, its procedure, and how doctors interpret its results.

How does a bone densitometry work?

A bone densitometry (known by the acronym DEXA or DXA) is a test to determine bone mineral density. It helps determine whether there’s been a loss of integrity or mineralization in the bone tissue.

According to an article in RadiologyInfo.org, it uses a small dose of ionizing radiation. It’s just how it makes it possible to obtain images of the bones. The test is quick, simple, and noninvasive.

It usually focuses on bones of the hip, spine, and forearm. However, they may also examine other parts such as the heel, fingers, or wrist.

An imaging technologist is in charge of conducting the procedure and a physician subsequently analyzes it. Its main use is to assess a person’s risk of developing fractures associated with osteoporosis.

Doctors also use it to determine whether a patient requires treatment for osteoporosis. It’s also good for monitoring the effects of the treatment itself. The results of a bone densitometry should improve over the months if it works.

In addition, it has the advantage of leaving no trace of radiation in a patient. Moreover, it doesn’t lead to side effects although it isn’t always indicated. For example, there is a certain contraindication in the case of pregnant women.

Various bone densities.
The measurement of bone density makes it possible to establish the presence of osteoporosis and the effectiveness of the treatments put in place.

Why perform this test?

A bone densitometry can determine whether there’s a loss of bone density. This can be due to numerous factors but the loss of density definitely increases the risk of suffering a fracture.

For this reason, the study is useful for estimating the risk of fracture. This procedure is mainly for postmenopausal women, according to an article in the Centro Diagnóstico de Granada. Especially those with severe symptoms who don’t follow any hormonal treatment.

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

This test is also for people who take certain medications that affect the bones. Corticosteroids. Hyperparathyroidism is another indication for example. It’s a pathology that consists of increased secretion of parathyroid hormone (PTH).

This hormone is responsible for regulating the metabolism of calcium and phosphorus. This is because these are two of the most important minerals in bone structure and density. Thus, having a family or personal history of hip or spine fractures is another reason to have the test.

How to prepare for a bone densitometry test

A bone densitometry is a simple test that requires no previous preparation. It doesn’t cause any discomfort and doesn’t require much time. Clínica Universidad de Navarra states that the test lasts approximately half an hour.

Ideally,  wear comfortable clothes and no accessories or jewelry. You must remove any metallic object before the test. The patient is to lie still during the procedure.

You can eat as usual the day before the test. However, you must stop taking calcium supplements 24 hours before.

As we mentioned above, this procedure isn’t a good idea for pregnant women. Thus, it’s essential to inform the doctor if there’s a chance of an ongoing pregnancy. Also inform them if you’ve undergone a recent test with a contrast medium, such as a CT scan.

What can the results of this test indicate?

Physicians usually interpret the results of bone densitometry. The Sociedad Española de Geriatría Gerontología describes that you obtain a series of digitized and colored images. They must compare them with the values established as normal for the age group and sex to which the patient belongs.

In this way, they obtain two values or scores.

  • 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. A T-score below -1.1 is low, i.e. osteopenia. The T-score must be below -2.5 in order for osteoporosis to be present.
  • The other score they may obtain is the Z. This compares the patient with a group of people of the same age, sex, and similar physical condition. It allows them to monitor the course of treatment.
A doctor explaining an X-ray.
The follow-up of osteoporosis with densitometry makes it possible to evaluate the effectiveness of treatment with calcium and fixative drugs.

Find out What Are the Risk Factors for Osteoporosis?

What else should you know about bone densitometry?

You should inform your doctor of all medications and dietary supplements you’re taking prior to the procedure. You don’t need to fast, but you should have gone at least one day without taking calcium. In addition to jewelry and metal objects, it’ll be necessary to remove any glasses and dentures.

What you must keep in mind is that bone densitometry cannot predict who’s going to have a fracture. However, it does provide guidance on the relative risk of one.

Analyses on the spine or hip are useful to check the response to treatment. However, those performed on the heel or wrist aren’t useful for this purpose. They’re definitely useful for predicting the risk of fracture.

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A bone densitometry is a simple harmless test

This kind of test makes it possible to study bone mineral density as it uses X-rays. It helps check if there’s a problem with osteoporosis and even monitors its treatment.

Thanks to it, it’s possible to predict how much risk of fracture a person has. This is why, in addition to the fact that’s safe and simple, doctors use it regularly nowadays.

  • Densitometría ósea: Una prueba predictiva. (n.d.). Retrieved March 6, 2021, from https://www.segg.es/ciudadania/2012/03/26/densitometria-osea-una-prueba-predictiva
  • Densitometría ósea. Pruebas diagnósticas. Clínica Universidad de Navarra. (n.d.). Retrieved March 6, 2021, from https://www.cun.es/enfermedades-tratamientos/pruebas-diagnosticas/densitometria-osea
  • ¿Qué es y para que sirve una prueba de densitometría ósea? – Centro Diagnostico Granada. (n.d.). Retrieved March 6, 2021, from https://www.centrodiagnostico.com/que-es-una-desintometria-osea/
  • Densitometría ósea (DEXA, DXA). (n.d.). Retrieved March 5, 2021, from https://www.radiologyinfo.org/sp/info.cfm?pg=dexa