Bone Density Pt 2: Testing and Diagnosis

 

Last time, we discussed the risk factors for low bone mineral density leading to osteoporosis. Click here-Low Bone Density Risk Factors If you have many of these risk factors you may want to talk to your doctor about getting tested before the standard screening age. How do they determine what’s going on with your bones?

While there may be some outward signs that your bone may be thinning such as

  • receding gums
  • decreased grip strength
  • brittle fingernails
  • loss of height/ bent over posture
  • you fractured a bone for no good reason

you can’t have a diagnosis without proper testing. Right now, the gold standard is the DXA scan.

When you have your screening at age 65 or if you feel you are at high risk and choose to have it earlier, that is the test your doctor will tell you to have.

 

What is DXA (Duel Energy X-ray Absorptiometry)

Dxa is a low dose radiation x-ray that measures the mineral density in your bones. I won’t  get into how it works. If you’re interested you can check that out yourself. It is a good predictor of future fractures.

The QTC type is best, because it measures at your hip and spine. The other types measure at places like the heel, finger and forearm. Those are generally used when it is not possible to test the hip and spine.

 

What Does It Tell You

The results give you a

  1.   T-score – The compares your BMD to others at age 26-29 of the same gender.
  2.   Z-score – Compares your bone density to others of the same age and gender.

Your T-score and Z-score are put on a chart showing you if you are normal, have low bone density (osteopenia) or have osteoporosis.

Remember, Osteopenia is not a diagnosis or disease, but it should be a wake-up call that you need to start taking action.

These scores are only one aspect of your bone health. Bone strength needs to be considered as well as bone architecture.

*Always ask for a copy of your diagnostic scan pages, including the images.

 

Considerations Before Testing

Remove any metal that will interfere with the test.

Don’t take calcium  or other mineral supplements 24 hours before the test. It can show a false higher density.

Don’t have the test if you are pregnant.

 

Problems

This test isn’t perfect. It is possible to have errors. So how do you get the most reliable results?

The reason results may not be accurate is twofold. First, in a few states, technologists giving the test are not required to be certified. You might want to check with yours. Many only receive the training to use the machine given by the manufacturer. The radiologist also does not require training. This is slowly changing as more states seek to improve testing reliability.

Secondly, machines vary. Different machines can give slightly different results. Make sure you use the exact same machine for the most reliable results.

Improper hip rotation can cause 10% error in measurement. Always make sure they use the same hip and position it the same way. Rotation of too much or too little will incorrectly show a higher density.

Drawing the bone borders incorrectly can incorrectly show gain or loss.

All variables should be the same. Even your vitamin D levels can affect the results, so always get it at the same time of year.

Arthritis in the bone scanned can cause a false high density.

False positives can show in those with small frames.

 

 

 FRAX test

This test evaluates your risk of fracture within the next 10 years.

Your bone QUALITY is just as important as the density of your bone. Over half the people with osteoporosis don’t fracture and many people with normal bone density do.

The FRAX test combines your osteoporosis risk factors plus your chances of falling (due to muscle weakness, poor balance and poor coordination). Then calculates your risk.

There are online FRAX tests available.

 

Other Tests

There are other available tests, but they are used less often. They may show various markers, but they don’t usually determine the cause for the marker.

However, since DXA are only done every 2 years, these other tests have the ability to show effectiveness earlier to evaluate treatment whether it be drugs, diet or exercise.

-VFA – Vertebral Fracture Assessment – Checks for spinal fractures you may not know you have. Used for low trauma fractures, loss of height, stooped posture.

-Regular x-rays – can show fractures and VERY low density, but can’t be used to diagnose or measure severity.

 

Other Lab Tests

These check for chemicals in your blood and urine that are markers for bone formation and breakdown. Be aware, your insurance may or may not pay for these tests.

-NTx- N-telopeptide of crosslinked type I collagen. Urine test that measures your rate of bone loss and can be used to evaluate your therapy.  High levels mean rapid bone loss.

-Calcium in blood test – High levels mean bone is being lost. Calcium is in the body but not getting into the bone. (not absorbing calcium)

-Serum bone specific alkaline phosphatase – blood test – This is an enzyme produced by bone building. Indicates whether building is happening. Recommended if you are taking bisphosphonates. Elevated levels can indicate other serious conditions.

-Vitamin D Level – If you have low D levels your body can’t use calcium

You may also ask your doctor about testing for other reasons for bone loss. These include thyroid health, Celiac disease, overactive parathyroid, RA, various medications, etc.

 

Those are the basic tests. You will most likely be having the DXA scan at some point.  So if you are positive for low bone density, osteoporosis, or just want to get ahead of it before it happens, what can you do?

We’ll discuss some options next time.

*I am not a doctor or healthcare professional. I am learning along with you. Please consult your doctor to discuss your options.

If you have personal experience with bone loss, please share your wisdom with us, so that we can all benefit.

 

Some Resources:

Better Bones /testing

Diagnosing Osteoporosis

Schneider, Diane. The Complete Book of Bone Health.

Simpson, Lani. Dr. Lani’s No-Nonsense Bone Health Guide.

State Legislative & Regulatory Activity

Urinary N-telopeptide: The New Diagnostic Test for Osteoporosis

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