title: Characterization of neuropathies associated with elevated IgM serum levels.
abstract: BACKGROUND
  In contrast to the IgM monoclonal gammopathies the neuropathy associated with polyclonal IgM gammopathy has not been well characterized.
  
  
  OBJECTIVE
  To characterize the neuropathy in patients with elevated serum IgM.
  
  
  METHODS
  Retrospective review.
  
  
  METHODS
  Academically based neuropathy center.
  
  
  METHODS
  45 patients with elevated quantitative immunoglobulin M were identified.
  
  
  METHODS
  Patients are described with regard to clinical phenotype, electrodiagnostic features of demyelination or focality, presence of IgM monoclonal gammopathy, and presence of autoantibody activity.
  
  
  RESULTS
  Elevated IgM levels occurred in 45 (11.5%) of 391 patients. Of these, 24 (53%) had polyclonal gammopathy and 21 (47%) had an IgM monoclonal gammopathy. Anti-nerve antibodies occurred in 14/21 (67%) of patients with monoclonal gammopathy, as compared to 1/24 (4%) with polyclonal gammopathy. Clinically, most patients in all groups had a predominantly large fiber sensory neuropathy. Thirty patients underwent electrodiagnostic testing. Of these, 22/30 (73%) fulfilled at least one published criteria for CIDP, including 92% of the monoclonal gammopathy patients and 59% of the polyclonal gammopathy patients. Fifteen of the 30 patients had evidence of focality or multifocality, with 14 of these 15 showing evidence of demyelination.
  
  
  CONCLUSIONS
  Monoclonal and polyclonal IgM patients have similar distributions of neuropathy phenotypes. Neuropathy in association with elevated serum IgM, with or without monoclonal gammopathy or autoantibody activity, is more likely to be demyelinating or multifocal. Serum quantitative IgM level and immunofixation in neuropathy patients may aid in identification of an immune mediated or a demyelinating component.
authors.affiliation: Peripheral Neuropathy Center, Department of Neurology, Weill Medical College of Cornell University, 635 Madison Ave., Suite 400, New York, NY 10022, USA. argoldfarb@juno.com
authors.forename: Adina R
authors.initials: AR
authors.lastname: Goldfarb
authors.forename: Howard W
authors.initials: HW
authors.lastname: Sander
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Brannagan
authors.forename: Paul
authors.initials: P
authors.lastname: Magda
authors.forename: Norman
authors.initials: N
authors.lastname: Latov
mesh_terms: D000911:Antibodies, Monoclonal / Q000097:blood / Q000276:immunology; D001323:Autoantibodies / Q000097:blood / Q000276:immunology; D004568:Electrodiagnosis; D006801:Humans; D007075:Immunoglobulin M / Q000097:blood* / Q000276:immunology*; D009186:Myelin Sheath / Q000276:immunology / Q000473:pathology; D009413:Nerve Fibers, Myelinated / Q000276:immunology / Q000473:pathology; D010265:Paraproteinemias / Q000097:blood / Q000276:immunology; D010525:Peripheral Nerves / Q000276:immunology / Q000473:pathology / Q000503:physiopathology; D010523:Peripheral Nervous System Diseases / Q000097:blood* / Q000175:diagnosis / Q000276:immunology*; D010641:Phenotype; D011129:Polyradiculoneuropathy / Q000097:blood* / Q000175:diagnosis / Q000276:immunology*; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D015854:Up-Regulation / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D001323:Autoantibodies; D007075:Immunoglobulin M