Diagnostic Schema:
I = Plasmacytoma on tissue biopsy 
II = Bone marrow with greater than 30% plasma cells 
III = Monoclonal globulin spike on serum protein electrophoresis, with an immunoglobulin G (IgG) peak of greater than 3.5 g/dL or an immunoglobulin A (IgA) peak of greater than 2 g/dL, or urine protein electrophoresis (in the presence of amyloidosis) result of greater than 1 g/24 h 
a = Bone marrow with 10-30% plasma cells 
b = Monoclonal globulin spike present but less than category III 
c = Lytic bone lesions 
d = Residual normal immunoglobulin M (IgM) level of less than 50 mg/dL, IgA level of less than 100 mg/dL, or IgG level of less than 600 mg/dL