title: Establishment, value assignment, and characterization of new WHO reference reagents for six molecular forms of human chorionic gonadotropin.
abstract: BACKGROUND
  The International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) established a Working Group to investigate means of improving the comparability of immunoassays for human chorionic gonadotropin (hCG), which was selected as a prototype glycoprotein analyte. The Working Group identified development of unambiguous nomenclature and production of new highly purified International Reference Reagents calibrated in substance concentrations as its primary objectives.
  
  
  METHODS
  Preparations of intact hCG, nicked hCG, hCG beta-subunit, nicked hCG beta-subunit, hCG alpha-subunit, and hCG beta-core fragment were purified from a crude urinary hCG preparation, ampouled, lyophilized, and assigned values in substance concentrations (mol/L). Value assignment and accelerated degradation studies were carried out in accordance with WHO protocols for International Reference Reagents.
  
  
  RESULTS
  The ampouled standards were assigned final values based on the recovery of immunoreactive material after reconstitution. The degradation studies showed that the standards were highly stable.
  
  
  CONCLUSIONS
  The nomenclature of hCG-related molecules and immunoassays has been adopted by the IFCC, and the standards prepared and characterized by the Working Group have been formally adopted by the WHO as the First International Reference Reagents for six hCG-related molecules. These developments will enable better understanding of what assays for hCG measure and should ultimately help to improve the clinical application of these assays.
authors.affiliation: National Institute for Biological Standards and Control, Potters Bar, Herts, UK.
authors.forename: Adrian
authors.initials: A
authors.lastname: Bristow
authors.forename: Peter
authors.initials: P
authors.lastname: Berger
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Bidart
authors.forename: Steven
authors.initials: S
authors.lastname: Birken
authors.forename: Robert
authors.initials: R
authors.lastname: Norman
authors.forename: Ulf-Håkan
authors.initials: UH
authors.lastname: Stenman
authors.forename: Catharine
authors.initials: C
authors.lastname: Sturgeon
mesh_terms: D006063:Chorionic Gonadotropin / Q000032:analysis / Q000592:standards*; D006801:Humans; D007118:Immunoassay / Q000592:standards; D021122:Protein Subunits / Q000032:analysis / Q000592:standards; D012015:Reference Standards; D009626:Terminology as Topic; D014944:World Health Organization
chemical_list: D006063:Chorionic Gonadotropin; D021122:Protein Subunits