title: Automated two-site immunofluorescent assay for the measurement of serum chromogranin A.
abstract: OBJECTIVE
  Chromogranin A (CgA) is the best-characterized biological marker common to neuroendocrine tumours and is therefore recommended for their diagnosis. The measurement of serum CgA is of great importance for reaching an early diagnosis and thus reducing the delay before treatment is instigated. The Kryptor CgA assay is the first fully automated assay available. The aim of this study was to evaluate its analytical performance.
  
  
  METHODS
  The imprecision and linearity of the Kryptor CgA assay were evaluated. This assay was compared with the Cis Bio CgA RIA assay in 78 serum samples. Its clinical utility was assessed in serum from 229 patients.
  
  
  RESULTS
  The study performed on imprecision of Kryptor measurements showed intra- and inter-run CVs ≤ 5%. The study of linearity showed a satisfactory recovery rate for CgA concentrations up to 1200 μg/L. The Kryptor and RIA assays agreed well on the basis of the cut-off values provided by the two manufacturers. The Bland and Altman plot of the values obtained (range: 20-5560 μg/L) provided a mean difference of -10.1 μg/L (SD: 116). The clinical sensitivities of Kryptor CgA for diagnosis of pheochromocytoma and paraganglioma (n 20) and gastroenteropancreatic NETs (n 17) were respectively 100 and 94%.
  
  
  CONCLUSIONS
  The Kryptor assay for CgA shows reliable analytical and clinical characteristics and allows a fast delivery of results.
authors.affiliation: Department of Clinical Chemistry, Hôpital Cochin, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris, France. Electronic address: theodora.popovici@cch.aphp.fr.
authors.forename: Théodora
authors.initials: T
authors.lastname: Popovici
authors.affiliation: Department of Clinical Chemistry, Hôpital Cochin, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris, France. Electronic address: baptiste.moreira@gmail.com.
authors.forename: Baptiste
authors.initials: B
authors.lastname: Moreira
authors.affiliation: Department of Cellular Biology, Hôpital Saint-Louis, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris, France. Electronic address: marie-helene.schlageter@sls.aphp.fr.
authors.forename: Marie-Hélène
authors.initials: MH
authors.lastname: Schlageter
authors.affiliation: Department of Clinical Chemistry, Hôpital Cochin, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris, France. Electronic address: phuong-nhi.bories@cch.aphp.fr.
authors.forename: Phuong-Nhi
authors.initials: PN
authors.lastname: Bories
mesh_terms: D014408:Biomarkers, Tumor / Q000097:blood; D053379:Chromogranin A / Q000097:blood*; D005455:Fluorescent Antibody Technique / Q000379:methods*; D006801:Humans; D018358:Neuroendocrine Tumors / Q000097:blood; D015203:Reproducibility of Results
chemical_list: D014408:Biomarkers, Tumor; D053379:Chromogranin A
keywords: Automated assay; CgA; Chromogranin A; ENETS; European Neuroendocrine Tumor Society; GEP; Kryptor; NANETS; NET; Neuroendocrine tumour; North American Neuroendocrine Tumor Society; PPI; UK and Ireland Neuroendocrine Tumour Society; UKINETS; chromogranin A; gastro-entero-pancreatic; neuroendocrine tumour; proton pump inhibitors