title: Do acetylcholine receptor and striated muscle antibodies predict the presence of thymoma in patients with myasthenia gravis?
abstract: BACKGROUND
  Acetylcholine receptor (AChR) and striated muscle antibodies (StrAbs) are found frequently in myasthenia gravis (MG) patients with thymoma. In this study we aimed to determine the positive predictive value (PPV) and negative predictive value (NPV) of these antibodies for thymoma in patients with MG.
  
  
  METHODS
  Antibody findings, thymic histology, and onset age were reviewed for 1141 patients with MG. PPV and NPV of these antibodies for thymoma were determined.
  
  
  RESULTS
  The PPV of AChR binding antibodies plus StrAbs was highest (50.0%) with onset before the age of 40 years. The PPV of all antibodies was low (<9%) after age 40. Higher StrAb levels did not increase the PPV. The NPV of AChR binding antibodies was high (99.7%) for all ages.
  
  
  CONCLUSIONS
  Patients without AChR binding antibody are not likely to have a thymoma. StrAbs and AChR binding antibodies are not diagnostic for thymoma, but in early-onset MG their presence should raise the clinical suspicion for thymoma.
authors.affiliation: Neuromuscular Section, Division of Neurology, Department of Medicine, Duke University Medical Center, DUMC 3403, Durham, North Carolina, 27710, USA.
authors.forename: Emily
authors.initials: E
authors.lastname: Choi Decroos
authors.forename: Lisa D
authors.initials: LD
authors.lastname: Hobson-Webb
authors.forename: Vern C
authors.initials: VC
authors.lastname: Juel
authors.forename: Janice M
authors.initials: JM
authors.lastname: Massey
authors.forename: Donald B
authors.initials: DB
authors.lastname: Sanders
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D000906:Antibodies / Q000097:blood* / Q000276:immunology; D001323:Autoantibodies / Q000097:blood; D015415:Biomarkers / Q000097:blood; D002648:Child; D002675:Child, Preschool; D015897:Comorbidity; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D054792:Muscle, Striated / Q000276:immunology*; D009157:Myasthenia Gravis / Q000453:epidemiology*; D011950:Receptors, Cholinergic / Q000276:immunology*; D012189:Retrospective Studies; D013945:Thymoma / Q000175:diagnosis / Q000453:epidemiology* / Q000276:immunology; D013953:Thymus Neoplasms / Q000175:diagnosis / Q000453:epidemiology* / Q000276:immunology; D055815:Young Adult
chemical_list: D000906:Antibodies; D001323:Autoantibodies; D015415:Biomarkers; D011950:Receptors, Cholinergic; C051931:myasthenia gravis anti-skeletal muscle antibody
keywords: acetylcholine receptor antibody; myasthenia gravis predictive value; striated muscle antibody; thymoma