Serum C-Telopeptide, CTx
This test is used to assess the loss of bone mass (bone resorption) in cases of osteoporosis or other bone diseases such as Paget’s disease.
Throughout our lives, our bones are continually being remodelled in two steps, always beginning with the “breakdown” of a small part of bone (resorption) and followed by the replacement of the removed bone by new bone (formation). In osteoporosis, the bones are weakened because the breakdown occurs at a faster rate than the rebuilding. In Paget’s disease, both phases take place very quickly, causing pain and bone deformities. When bone is resorbed, fragments of the bone collagen are released into the bloodstream. One of these fragments is called “C-telopeptide.” The higher the C-telopeptide level in the blood, the greater the bone resorption. C-telopeptide levels decrease within a few weeks when osteoporosis is being treated successfully with drugs (bisphosphonates, etc.). Comparatively, it takes at least one to two years for the treatment effects to be seen in a bone density test.