The main indicators of multiple myeloma are the following: first, the proportion of bone marrow plasma cells at the time of diagnosis of myeloma, or the site of extramedullary plasma cell invasion. Second, whether the value of abnormal M protein secreted by myeloma plasma cells is elevated or decreased, whether the immunofixation electrophoresis in serum or urine is negative or positive, and the degree of decrease of serum free light chain value. Thirdly, it is also necessary to refer to the degree of anemia and renal impairment, blood calcium level, and the degree of bone destruction, especially in the bones of the limbs and the skull.