C-telopeptide (C-terminal telopeptide of type 1 collagen (CTx)) – is a marker for bone resorption. It is used as a monitoring tool for anti-resorptive therapies. Some of these therapies include bisphosphonates and hormone replacement therapy in postmenopausal women and people with low bone mass (osteopenia).
Procollagen type 1 N-terminal propeptide – Is a marker for bone formation made by osteoblasts. The test reflects rate of and bone formation and may be ordered along with bone resorption marker such as C or N-telopeptide. It is the most sensitive marker of bone formation and particularly useful for monitoring bone formation therapies and anti-resorptive therapies. It is also recommended that the test be performed at baseline before starting osteoporosis therapy and again 3 to 6 months later.
N-telopeptide (N-terminal telopeptide of type 1 collagen (NTx)) – This is a peptide fragment from the amino terminal end of the protein matrix. It is another marker used to monitor therapy.