Note: People taking bisphophonates should read the special advisory on a potential complication of bisphosphonate therapy.

Many patients with myeloma develop bone disease. Bone disease can cause the bones to become thinner and weaker (osteoporosis), and it can make holes appear in the bone (lytic lesions). The weakened bone that results is more likely to break under minor pressure or injury (pathologic fracture). The bones most commonly affected are the axial skeleton (spine, pelvis, ribs, and skull) and the upper ends of the long bones of the arms and legs. Myeloma cells cause bone disease by sending signals to certain bone cells called osteoclasts, causing them to break down bone. In addition to giving rise to bone disease, this process also releases calcium; if this release happens too quickly, a condition called hypercalcemia can occur. Both myeloma bone disease and hypercalcemia can be treated with a group of drugs called bisphosphonates.