title: Monoclonal gammopathy of undetermined significance and smoldering multiple myeloma.
abstract: 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.
authors.affiliation: Department of Medicine, Laboratory Medicine & Pathology, College of Medicine Mayo Clinic, Rochester, MN 55905, USA. Kyle.robert@mayo.edu
authors.forename: Robert A
authors.initials: RA
authors.lastname: Kyle
authors.forename: S Vincent
authors.initials: SV
authors.lastname: Rajkumar
mesh_terms: D003937:Diagnosis, Differential; D018450:Disease Progression; D006801:Humans; D008998:Monoclonal Gammopathy of Undetermined Significance / Q000473:pathology*; D009101:Multiple Myeloma / Q000473:pathology*; D011379:Prognosis; D018570:Risk Assessment; D012307:Risk Factors