How do I interpret my NTx score? (2024)

Was your Dxa scan done on a Norland brand scanner? I’m guessing this because they used to report T-scores out to two decimals while other brands only report to 1decimal. Also their older scanners did not calculate a total hip score.

Why is this important?

If it was done in an older Norland scanner using the Norland 2001 normal database, the T-scores at the femur neck reported out much lower than they would be on the same day if scanned on a Hologic or GE Lunar device.

In reply to dxaguru's comment

In reply to AndreaMary's comment

In reply to bobbcat63's comment

Hi Bobbcat & AndreaMary,

Re (AndreaMary): "From what I’ve read, petite size can skew the numbers to make things look worse.".........

Re (Bobbcat): "I do wonder about my body size and how bad those T-score numbers really are.".........

From the University of Illinois blog :

❝ How Do You Know If You Have a Small Frame?

Determining frame size: To determine your body frame size, measure the wrist with a tape measure. Measure your height without shoes. Check your wrist size based on your height below. Having a small frame is considered to be a risk factor for osteoporosis.

Women:

height under 5'2"

small = wrist size less than 5.5"

medium = wrist size 5.5" to 5.75"

large = wrist size over 5.75"

height 5'2" to 5' 5"

small = wrist size less than 6"

medium = wrist size 6" to 6.25"

large = wrist size over 6.25"

height over 5' 5"

small = wrist size less than 6.25"

medium = wrist size 6.25" to 6.5"

large = wrist size over 6.5"

Men:

height over 5' 5"

small = wrist size 5.5" to 6.5"

medium = wrist size 6.5" to 7.5"

large = wrist size over 7.5"

University of Illinois Extension | University of Illinois at Urbana-Champaign | College of ACES ❞

Source: unfortunately, the link to the University of Illinois "lost its wheels" .........

As proxy, the following link via the University of Washington :

https://medlineplus.gov/ency/imagepages/17182.htm.........

All The Best,

Vicuña

If you have a wrist size of 5.

and height of 5 feet are you considered small frame?

Like BobbCat, I find the matter confusing. My dexa numbers would make it seem I am frail beyond belief, but I am an active mountain biker and runner without any fractures at all. Even yesterday, I rode hard for 2 hours and crashed hard 3 times, landing on wrists, and once with a handlebar so hard into my breast bone that I have a totally blue & dark red bruised right breast today (hilarious, colorful, but not broken), yet look at my dexa numbers on 11-5-20 (10 days ago) from a GE machine at a specialist's office: wrist/forearm -3.9; lumbar spine -4.2; hips/dual femur -2.1.

Those numbers are stupefying when I think if how often I go tumbling during trail running and biking. Last Nov. 2019, I had a dexa on a Hologic that gave the hips a -3.2 and spine -4.6. And that doctor failed to call and tell me about it until July 2020, and then failed to prescribe any meds. So how did I "improve" over a year in the hips from -3.2 to -2.1 without any Rx? And in the lumbar spine from 4.6 to 4.2?

Unless. . . AndreaMary has it right, and my size is affecting the dexa. My height is 5'0, my weight is 105, and my wrist is 5-1/8".

I didn't believe the first dexa results and switched doctors. I am going with the Tymlos treatment because I feel I must err on the side of caution if I want to keep riding hard, running hard, carrying my half of the canoe down to the water, and generally tumbling my way through my recreational time. But my lumbar xray showed absolutely no fractures or arthritic changes, and I had a straight spine with good spacing between vertebra. I am not a person who engages in worthless denial, but I am having difficulty believing that I have severe osteoporosis of the wrist and spine. It makes no sense.

If someone has specific reading material on how specifically small size affects bone density diagnostic results, I sure wish you would post it. I have found lots of literature that states generally that size extremes appear to affect results from a dexa, but it seems that specific examples are always in the heavier extremes. I have found nothing that says anything about tiny bones.

(Or maybe it's irrelevant, and having tiny bones means you have less bone mass to lose? ) I'll appreciate any reference material anyone can post.

In reply to Betty76's comment

Hi Betty & PamRea,

Re (Betty): "If you have a wrist size of 5.

and height of 5 feet are you considered small frame? ".........

Re (PamRea): "My height is 5'0, my weight is 105, and my wrist is 5-1/8". ".........

According to the aforementioned data__height under 5'2";

small = wrist size less than 5.5"__so, apparently, a small frame.........

Note: the data within the university blogosphere via NIH Library of Medicine. Hence, a legit source, in my opinion.........

Good Tidings,

Vicuña

P.S. PamRea & Betty & Bobbcat & AndreaMary

Ay Yai Yai, Betty, beaucoup hurricanes in your neck of the woods. Stay safe.........

Welcome to Inspire, PamRea.........

The endocrinologist, Endodoc, once roamed in these parts (currently in hiatus). His archival post a bit lengthy, though worthwhile, in my opinion. If pressed for time, simply scroll down to the eighth and last paragraph, which shine a light on "small bones" :

❝ Most patients and most otherwise good physicians who never specifically studied bone metabolism are unaware of the fact that DXA machines do not actually measure BMD. I realize that sounds bizarre, but it is true. If you look at the units for your BMD values on DXA, they are grams per square centimeter (g/cm2). There is no universe where mass/area equals density. D=M/V, in other words, density equals mass over volume. The DXA measures your BMC (bone mineral content), based on the level of x-rays that reach the detector. More mineral in the path of the beam, less x-rays make it to the detector = higher BMC. Less mineral in the path of the beam, more x-rays make it to the detector = lower BMC.

If DXA machines divided the BMC they actually measure by the volume of the bone scanned, the units would be g/cm3, it would actually be measuring density, and we wouldn't be having this discussion. However, they divide the BMC by the area of the ROI (region of Interest) that the DXA and/or DXA tech puts over the image of your bone; hence, the units are g/cm2. If you've ever seen your hip scan, you will see a rectangle that represents the ROI for the femoral neck sub-region. You will see a smaller square box, either close to the rectangle or touching/partially within the rectangle - that's the ROI for the Ward's triangle sub-region.

The problem with DXA being an areal measurement as opposed to a true volumetric measurement is that, as a result, it systematically over-estimates BMD on individuals whose bones are larger than average (think: those 5'10" gals with the the big wrists who played rugby in college), and systematically under-estimates BMD in individuals whose bones are more petite than average (think: those 5'2" gals withthe small wrists and ankles who did ballet in college).

The other things that most otherwise good and smart physicians don't appear to understand is that the definition of osteoporosis is an increased risk of having a fracture. Honest. It is not just having a T-score in some bone that is -2.5 or less. Since 2003, physicians are supposed to be relying on the FRAX calculator (http://www.shef.ac.uk/FRAX/tool.jsp?locationValue=9) or the FORE-FRC calculator (riskcalculator.fore.org), both of which calculate one's 10-year risk of having both 1) an major osteoporotic fracture, and 2) a hip fracture.

If you use one of these to calculate your risk, all you will need to know is your age, gender, height, weight, femoral neck BMD value in g/cm2 and the machine type (e.g., hologic or GE-Lunar or Norland) for FRAX, and your Femoral Neck T-score (for FORE-FRC), as well as if you have experienced a fracture, have rheumatoid arthritis, if either parent fractured a hip, if you are currently taking steroids, if you smoke, and if you drink more than 3 alcoholic drinks per day. For past fractures, they are asking about past osteoporotic fractures. This can simply be defined as any fracture not resulting from major trauma after age 45 with the exception of fractures of the face, skull, fingers, hands, toes, feet, or knee caps.

The other thing to know about these calculators (which, while very similar do not always give exactly the same risk numbers) is that "high risk" meaning osteoporosis is generally accepted to be if one's 10-year risk of any major fracture is at least 20%, or if one's 10-year risk of hip fracture is at least 3.0%. Now, most folks might tend to agree that that if they had a 1/5 risk of a major fracture over 10 years that's a high risk, but many might not think that having a 3% risk of a hip fracture over 10 years (i.e., a 97% likelihood of NOT breaking your hip over the next 10 years) that that's a "high risk" worth worrying about. FYI, the "3.0%" figure comes from a Canadian study that established the cost-effectiveness of treating varying risk levels for SOCIETY (i.e., the Canadian government). Assuming the approved drugs reduce the risk by about 35% on average, and given the costs of BPs, it is worthwhile for a country to treat everyone who has at least 3% risk of hip fracture over 10 years. But this might not be the best thing for every individual patient.....

Try playing with the calculators. You will see that a 50 yo with a femoral neck T-score of -2.6 and no other risk factors can have very low risk, whereas an 88 yo with at least 1 risk factor can have a high risk of fracture with a T-score of -1.1.

Because of the confound of bone size on DXA, many smallish women have t-scores of < -2.0 when they are at their peak BMD at age 25. So if their T-score is -2.5 at the time they enter the menopause, it's likely (absent other risk factors, like bone toxic drugs or diseases) to represent an approximation of their peak bone mass. Most non-expert physicians, however, make the idiotic assumption that "everyone starts at average" (trust me, half are above and half are below, and with DXA it's only the big-boned folks who are above), so they interpret your baseline T-score of -2.5 at age 50 as if you've already lost 2.5 SD [standard deviations] of your bone mass. This is absurd. ❞

Source: https://www.inspire.com/windblown/journal/forteo-results/reply/1478797/.........

Sincerely,

Vicuña

In reply to Vicuna's comment

Bonjour Bobbcat,

A reference range of NTx values on your lab test results?.........

As per Quest Diagnostics, only a range for males and premenopausal women within their site (I have no commercial nexus with Quest Diagnostics) :

❝ Reference Range(s)

Collagen Cross-Linked N-Telopeptide (NTx), 24-Hour Urine

Male

18-29 Years5-88 nM BCE/mM creat

30-39 Years7-51 nM BCE/mM creat

40-49 Years5-47 nM BCE/mM creat

50-60 Years6-43 nM BCE/mM creat

Female

Premenopausal5-79 nM BCE/mM creat

Results are primarily used for monitoring the response to therapy. A value within the premenopausal reference range does not rule out osteoporosis nor the need for therapy.

Clinical Significance

Collagen Cross-Linked N-Telopeptide (NTx), 24-Hour Urine -

NTx is useful to assess bone resorption in patients with metabolic bone disease and monitor therapy to slow or halt osteoporotic bone loss. A decline of 30% or more of NTx over a six-month period suggests effective therapy. ❞ .........

Source: https://testdirectory.questdiagnostics.com/test/test-detail/36421/?cc=MASTER.........

Onward,

Vicuña

In reply to Vicuna's comment

Although I am post-menopausal, I'm thinking my score of 43 seems pretty good. Do you think I could go as far as to say I'm not losing bone at a bad rate?

Thank you for your help with my questions Vicuna!

Buon Giorno Bobbcat,

In a surreal universe, I would answer your inquiry wily nily, without rhyme nor reason.........

Now back to reality. I'm not a doctor. Nor am I some hifalutin PhD researcher on the up and up. Ahh, haha. Just my notion that the NTx Reference Range might be designated on your lab report. Ever ask your doctor about the significance, if any, of your NTx score?.........

The most intelligent thing I can say: "I don't know." I can also recommend a book, or at least, the following Abstract, hot off the press :

Osteoporosis Markers (2020)

https://www.ncbi.nlm.nih.gov/books/NBK559306/#!po=1.31579.........

Good Night

Cheers

Vicuña

In reply to Vicuna's comment

Unfortunately, the only reference range I've been able to find is pre menopausal. I will definitely take a look at the book you recommended.

Thanks again for your help!

Cindy