What are the clinical applications of C-terminal telopeptide testing?

Updated: Feb 18, 2020
  • Author: Carlos Solano Loran, MD; Chief Editor: Eric B Staros, MD  more...
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Answer

Answer

In addition to the traditional evaluation of bone mineral density, biochemical markers of bone resorption provide additional predictive information on a patient’s fracture risk. Preventive therapy with antiresorptive agents is warranted for patients with low BMD or high marker values, because they would be at risk for osteoporosis.

Although results of prospective studies assessing the relationship between the rate of bone loss and biochemical markers of bone turnover have been conflicting, the following guidelines apply to the use of bone markers in prediction of fragility fractures:

  • Bone resorption markers elevated more than +2 SD/T score more than 2 above the premenopausal normal range is associated with approximately 2-fold increase in osteoporotic fracture risk.

  • In selected patients whose clinical risk factors and BMD assessment are not sufficient to allow treatment decision, resorption markers can be used to assess fracture risk. [4]

  • A high level of bone turnover marker (T score >3) is highly suggestive of alternative metabolic bone diseases, including malignancy, in patients with osteoporosis.

  • Normal values are reference values derived from the evaluation of healthy, premenopausal women aged 30-45 years.

A study by Massera et al indicated that to a limited degree, C-telopeptide of type I collagen (CTX) levels positively correspond to the risk of hip fracture in postmenopausal women. Linear spline analysis demonstrated the association, but only for CTX levels up to the middle-upper range. Levels beyond this, however, corresponded to marginally nonsignificant risk reductions. [5]

 

See also the Fracture Index WITH known Bone Mineral Density (BMD) calculator.

The lists below summarize recommendations for monitoring antiresorptive treatment in postmenopausal women with osteoporosis, using bone markers.

Types of marker include the following:

  • Bone resorption - Urine NTX, serum CTX, or urine CTX

  • Bone formation - Bone-specific alkaline phosphatase or osteocalcin (use 1 marker or 1 resorption and 1 formation marker.)

Intervals of measurement include the following:

  • Resorption markers - Prior to starting treatment and 3 or 6 months after treatment initiation

  • Formation markers - Prior to starting treatment and 6 months after treatment initiation


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