Bone markers in multiple myeloma

Bone disease, a hallmark of multiple myeloma occurs in the majority of the patients, is associated with bone pain, fractures, hypercalcemia and has major impacts on quality of life. Myeloma is characterized by a unique form of bone disease with osteolytic bone destruction that is not followed by reactive bone formation, resulting in extensive lytic lesions. This review will focus on the pathophysiology of osteoclast activation and osteoblast inhibition in multiple myeloma and on biochemical markers of bone turnover. Since osteolytic lesions do not rapidly heal in myeloma, X-rays cannot reflect the activity of bone disease during antimyeloma treatment. Activity in bone turnover does not parallel changes in monoclonal protein levels. Thus, there is a need for biochemical markers reflecting disease activity in bone. The utility, prognostic implications and limitations of classical and novel markers of bone remodeling (e.g. ICTP, NTx, TRACP-5b, osteoprotegerin, sRANKL) will be discussed in this overview.