Monoclonal gammopathy of undetermined significance and smoldering multiple myeloma

Robert A. Kyle, S. Vincent Rajkumar

Research output: Contribution to journalReview article

16 Scopus citations


Monoclonal gammopathy of undetermined significance (MGUS) is characterized by the presence of a serum monoclonal (M) protein level less than 3 g/dL, less than 10% clonal plasma cells in the bone marrow, and the absence of hypercalcemia, renal insufficiency, anemia, or bone lesions attributable to a clonal plasma cell disorder. Patients may be tested for a monoclonal gammopathy by serum protein electrophoresis, immunofixation, and the free light chain (FLC) assay. The prevalence of MGUS is 3% for persons more than 50 years of age and 5% in those more than 70 years of age. The risk of progression to multiple myeloma or a related disorder is 1% per year. The size and type of M protein, the number of bone marrow plasma cells, and the results of the FLC ratio are independent risk factors for progression. Smoldering multiple myeloma (SMM) is a more advanced premalignant phase than MGUS and is characterized by more than 3 g/dL of serum M protein, more than 10% clonal plasma cells in the bone marrow, or both, with no evidence of end-organ damage.

Original languageEnglish (US)
Pages (from-to)62-69
Number of pages8
JournalCurrent Hematologic Malignancy Reports
Issue number2
StatePublished - Apr 1 2010



  • Plasma cell disorders

ASJC Scopus subject areas

  • Hematology
  • Oncology
  • Cancer Research

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