title: Differences in total human chorionic gonadotropin immunoassay analytical specificity and ability to measure human chorionic gonadotropin in gestational trophoblastic disease and germ cell tumors.
abstract: OBJECTIVE
  To determine the ability of several radioimmunoassays and commercial two-site immunoassays to detect the first World Health Organization International Reference Reagents (IRRs) for 6 defined human chorionic gonadotropin (hCG) variants and to compare their performance in measuring hCG in sera from patients with gestational trophoblastic disease (GTD) and germ cell tumors (GCTs) of the testis or ovary.
  
  
  METHODS
  The reactivity of the different assays with the 6 IRRs together with the current fourth International Standard (IS, 75/589) was tested using 5 commercial two-site assays as well as 2 competitive polyclonal radioimmunoassays (RIAs) and a competitive monoclonal immunoassay. Individual samples from 41 patients (19 GCT and 22 GTD) with high circulating levels of hCG (range, 718-6,055,000 IU/L) were diluted and measured using the various immunoassays.
  
  
  RESULTS
  The results of 4 GCT patient samples varied markedly among the assays, including 1 sample that was grossly underestimated by 3 of the commercial assays.
  
  
  CONCLUSIONS
  Comparison of each assay's reactivity to the variant isoforms revealed that recognition of the isoforms was highly variable, particularly for hCGbeta and hCGbeta core fragment (hCGbetacf).
authors.affiliation: Charing Cross Gestational Trophoblastic Disease Centre, Charing Cross Campus of Imperial College Healthcare NHS Trust, London, United Kingdom.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Harvey
authors.forename: Hugh D C
authors.initials: HD
authors.lastname: Mitchell
authors.forename: Ulf-Håkan
authors.initials: UH
authors.lastname: Stenman
authors.forename: M A
authors.initials: MA
authors.lastname: Blankenstein
authors.forename: Kjell
authors.initials: K
authors.lastname: Nustad
authors.forename: Petra
authors.initials: P
authors.lastname: Stieber
authors.forename: Wilson
authors.initials: W
authors.lastname: Stewart
authors.forename: Philip M
authors.initials: PM
authors.lastname: Savage
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Seckl
authors.forename: Glenn D
authors.initials: GD
authors.lastname: Braunstein
mesh_terms: D000328:Adult; D000368:Aged; D002822:Choriocarcinoma / Q000097:blood*; D006063:Chorionic Gonadotropin / Q000097:blood*; D005260:Female; D006801:Humans; D002820:Hydatidiform Mole, Invasive / Q000097:blood*; D007118:Immunoassay / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009373:Neoplasms, Germ Cell and Embryonal / Q000097:blood*; D010051:Ovarian Neoplasms / Q000097:blood; D011247:Pregnancy; D013736:Testicular Neoplasms / Q000097:blood; D014594:Uterine Neoplasms / Q000097:blood
chemical_list: D006063:Chorionic Gonadotropin