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N-telopeptide (NTx) — a valuable marker of bone breakdown

By Dr. Susan E. Brown, PhD

Every day women are worried because they’ve been told that a DEXA test shows their bone density is that of an 80-year-old, or that they “must” take bone drugs.

But what worries me is that most of these women have NOT been told whether or not their bone loss is ongoing or if it occurred in the past. Knowing if your bone loss is still taking place is critical when it comes to truly understanding your risk of excessive bone loss, osteoporosis and fracture. Fortunately, a test is available that provides this information. Let’s learn about it. 

What is a NTx test? 

Bone is a living tissue made up of minerals, collagen, and many other constituents. As bone breaks down, its by-products appear in the blood and then are ultimately excreted in the urine. 

N-telopeptide or NTx is a biomarker for collagen fragments/collagen by-products released into the bloodstream and excreted in urine when bone tissue is being broken down. The NTx test measures the concentration of these biomarkers. High levels of NTx in the blood or urine indicate higher levels of byproducts and increased bone breakdown. 

When NTx tests are taken consistently for a woman diagnosed or at high risk for osteoporosis, it’s possible to understand whether her bone loss is active and/or excessive. On the other hand, NTx may show no increased breakdown, which could mean that excess bone loss is no longer taking place. Bone density as measured by DEXA only provides a static, snapshot of your bones, and doesn’t distinguish if bone loss is ongoing or not. 

The NTx test is especially valuable in monitoring the effectiveness of treatment plan for osteoporosis. For example, a decrease in NTx levels back into normal range over time may indicate that the treatment is helping to reduce bone resorption and improve bone health. 

At the Center for Better Bones, we use the Osteomark NTx urine test to determine if women are undergoing excessive bone loss.  We look to bring the urine NTx level down to the 40s, which in most cases indicates that bone breakdown has normalized. There are some cases, however, where bone breakdown is very low, but bone build-up is even lower. This condition, known as “low turnover osteoporosis,” is detected when a person has a low NTx, but is still losing significant bone (5-6%) as seen on bone density testing.

All of this is great information to have and can point to the best direction to take to restore your bone health.  Talk to your health care provider about NTx testing. Any woman concerned about her bone health would benefit from this simple test! 



Last Updated: October 22, 2023
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