Markers of bone turnover, measured in blood or urine, correlate with changes in the metabolic activity of bone.

The rate of bone remodelling is important. With ageing, the quantum of bone removed/ resorbed and the amount replaced/ formed becomes increasingly imbalanced. Consequently, the more bone remodelling units that are active at any one time, or the greater the activity of individual units, the greater the overall rate of bone loss.

Bone turnover markers are probably predictive of the rate of bone loss and could help determine the efficacy of treatment.