A person must have >10 % clonal plasma cells and any MDE to be diagnosed with myeloma. The biomarker criteria were added so that smouldering people with multiple myeloma at high risk of developing multiple myeloma could be diagnosed before organ damage occurred, so they would therefore have a better prognosis. Asymptomatic/smoldering myeloma:
Serum M protein >30 g/L (3 g/dL) or
Clonal plasma cells >10% on bone marrow biopsy and
No myeloma-related organ or tissue impairment
Monoclonal gammopathy of undetermined significance (MGUS):
Serum paraprotein <30 g/L (3 g/dL) and
Clonal plasma cells <10% on bone marrow biopsy and
No myeloma-related organ or tissue impairment or a related B-cell lymphoproliferative disorderRelated conditions include solitary plasmacytoma (a single tumor of plasma cells, typically treated with irradiation), plasma cell dyscrasia (where only the antibodies produce symptoms, e.g., AL amyloidosis), and peripheral neuropathy, organomegaly, endocrinopathy, monoclonal plasma cell disorder, and skin changes. Staging
In multiple myeloma, staging helps with prognostication but does not guide treatment decisions. The Durie-Salmon staging system was used historically and was replaced by the International Staging System (ISS), published by the International Myeloma Working Group In 2005. The revised ISS (R-ISS) was published in 2015 and incorporates cytogenetics and lactate dehydrogenase (LDH). : 1730–1 : 732–3 
Stage I: β2 microglobulin (β2M) < 3.5 mg/L, albumin ≥ 3.5 g/dL, normal cytogenetics, no elevated LDH
Stage II: Not classified under Stage I or Stage III
Stage III: β2M ≥ 5.5 mg/L and either elevated LDH or high-risk cytogenetics [t(4,14), t(14,16), and/or del(17p)]

Prevention
The risk of multiple myeloma can be reduced slightly by maintaining a normal body weight.
Several newer options are approved for the management of advanced disease:

belantamab mafodotin — a monoclonal antibody against B-cell maturation antigen (BCMA), also known as CD269, indicated for the treatment of adults with relapsed or refractory multiple myeloma who have received at least four prior therapies including an anti-CD38 monoclonal antibody, a proteasome inhibitor, and an immunomodulatory agent. carfilzomib—a proteasome inhibitor that is indicated:
as a single agent in people who have received one or more lines of therapy
in combination with dexamethasone or with lenalidomide and dexamethasone in people who have received one to three lines of therapy
daratumumab—a monoclonal antibody against CD38 indicated in people who have received at least three prior lines of therapy including a proteasome inhibitor and an immunomodulatory agent or who are double refractory to a proteasome inhibitor and an immunomodulatory agent
elotuzumab—an immunostimulatory humanized monoclonal antibody against SLAMF7 (also known as CD319) indicated in combination with lenalidomide and dexamethasone in people who have received one to three prior therapies
isatuximab—a monoclonal antibody against CD38 indicated in combination with pomalidomide and dexamethasone for the treatment of adults with multiple myeloma who have received at least two prior therapies including lenalidomide and a proteasome inhibitor.