How is multiple myeloma (MM) diagnosed?

Updated: May 11, 2021
  • Author: Dhaval Shah, MD; Chief Editor: Emmanuel C Besa, MD  more...
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The most widely accepted schema for the diagnosis of multiple myeloma (MM) uses particular combinations of laboratory, imaging, and procedure findings as diagnostic criteria. (See Workup.) The findings are as follows:

  • 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 (Ig) G peak of greater than 3.5 g/dL or an 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 IgM level less than 50 mg/dL, IgA level less than 100 mg/dL, or IgG level less than 600 mg/dL

The following combinations of findings are used to make the diagnosis of MM:

  • I plus b, c, or d
  • II plus b, c, or d
  • III plus a, c, or d
  • a plus b plus c
  • a plus b plus d

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