Multiple myeloma is prone to hypercalcemia. Since myeloma cells destroy normal bone cells, a large amount of calcium contained in the bone cells will enter the bloodstream, thus easily causing hypercalcemia. If hypercalcemia occurs, it often manifests as lack of appetite, nausea, vomiting, constipation, weakness, etc. In severe cases, it may cause blurred consciousness and lethargy. When hypercalcemia is present, in addition to combined chemotherapy, large amounts of fluids need to be administered and diuretics are used to promote calcium excretion. In some cases, hemodialysis is required, which can rapidly lower calcium. Patients should also be encouraged to be as active as possible to reduce bone decalcification and to prevent and reduce hypercalcemia.