Some of the biomarkers associated with bone formation and resorption are shown in Table 2.
Table 2. Markers of Bone Formation and Resorption.| Markers of Bone Formation | Markers of Bone Resorption |
| Osteocalcin | Deoxypyridinoline Alkaline phosphatase |
| Procollagen type 1 N-terminal propeptide | C-telopeptide (C-terminal telopeptide of type 1 collagen (CTx)) |
| Bone specific alkaline phosphatase (ALP) isoenzymes | N-telopeptide (N-terminal telopeptide of type 1 collagen (NTx)) |
| Type 1 collagen telopeptides Propeptide of type 1 procollagen | Tartrate-resistant acid phosphatase (TRAP) |
These biomarkers can be found in blood and urine, they measure the products of osteoblasts (bone forming cells) or they may measure collagen breakdown products that reflect bone resorption, such as deoxypyridinolines or C- or N-terminal telopeptides. Although the biomarkers are commonly used in clinical trials, their clinical usefulness is limited due to individual patient variability.
The most useful biomarkers are those that predict bone resorption and are used as a predictor of fracture risk and monitor treatment but should not be used to diagnose osteoporosis. A decrease in resorption markers usually reflects a reduction in bone building activity. If the biomarkers are used for monitoring it is important to obtain a baseline value before treatment, then recheck every 3 to 6 months until stable.
