Biochemical markers of bone turnover include markers of bone resorption which are produced by osteoclasts during bone resorption and markers of bone formation which are produced by osteoblasts during bone formation (Table1). Recently, ELISA based methods have been developed for measurement of other markers such as Osteoprotegerin and RANK ligand. They are proteins synthesised by osteoblasts and are seen to influence osteoclast formation, activation and bone resorption. Bone markers help to assess the overall rate of bone resorption or formation. But they cannot identify the type of bone or location of altered bone metabolism.