A high immunoglobulin IgG depends first on the degree of high. If IgG is greater than 35g/L and M protein is present in the serum, there is a possibility of multiple myeloma. Multiple myeloma is mainly a malignant clonal disease of plasma cells, which is caused by the increase of a single immunoglobulin, resulting in the inhibition of the synthesis of multiple immunoglobulins, thus causing a series of symptoms, which may also result in an increase of IgG. There is also, for example, macroglobulinemia, which has clonal proliferation of plasma cells and lymphocytes in the bone marrow, and the M protein is IgM without bone destruction, which is different from IgM multiple myeloma. Therefore, it is better to do a bone marrow aspiration to see if there are myeloma cells inside the bone marrow, and if it is greater than 30%, the diagnosis of multiple myeloma can be confirmed.