title: Measurements of chromogranin B can serve as a complement to chromogranin A.
abstract: OBJECTIVE
  CgA has been shown to be an excellent marker for neuroendocrine tumours. However, there are two major drawbacks with CgA measurements; elevated levels are common in patients with decreased renal function and in patients on treatment with proton pump inhibitors. These problems are not seen with CgB measurements. We have recently presented the development of 13 region-specific radioimmunoassays for measurements of CgB. A region-specific assay was identified, which measured higher concentrations of CgB than the other assays and seemed to be very useful as a marker for neuroendocrine tumours. The aim of the present study was therefore to further explore the diagnostic potential of this assay in the clinical management of patients with neuroendocrine tumours.
  
  
  METHODS
  Measurements of CgB with two methods were compared with CgA in plasma samples from patients investigated for neuroendocrine tumours (N=86), patients with decreased renal function (N=35) and patients on treatment with proton pump inhibitors (N=29).
  
  
  RESULTS
  The diagnostic sensitivity for the new CgB assay was almost as good as that for CgA. Furthermore, with CgB measurements we could avoid the falsely elevated levels of CgA found in patients with decreased renal function and treatment with proton pump inhibitors.
  
  
  CONCLUSIONS
  We conclude that the new CgB assay can serve as a complement to CgA measurements as an important tumour marker for neuroendocrine tumours.
authors.affiliation: Department of Medical Sciences, Clinical Chemistry, University Hospital, SE-751 85 Uppsala, Sweden. mats.stridsberg@akademiska.se <mats.stridsberg@akademiska.se>
authors.forename: Mats
authors.initials: M
authors.lastname: Stridsberg
authors.forename: Barbro
authors.initials: B
authors.lastname: Eriksson
authors.forename: Bengt
authors.initials: B
authors.lastname: Fellström
authors.forename: Gudjon
authors.initials: G
authors.lastname: Kristiansson
authors.forename: Eva
authors.initials: E
authors.lastname: Tiensuu Janson
mesh_terms: D014408:Biomarkers, Tumor / Q000097:blood*; D002276:Carcinoid Tumor / Q000097:blood; D053379:Chromogranin A / Q000097:blood*; D053378:Chromogranin B / Q000097:blood*; D006801:Humans; D018358:Neuroendocrine Tumors / Q000097:blood; D010190:Pancreatic Neoplasms / Q000097:blood; D011863:Radioimmunoassay
chemical_list: D014408:Biomarkers, Tumor; D053379:Chromogranin A; D053378:Chromogranin B