Differences in total human chorionic gonadotropin immunoassay analytical specificity and ability to measure human chorionic gonadotropin in gestational trophoblastic disease and germ cell tumors.
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).
Harvey
Richard A
RA
Charing Cross Gestational Trophoblastic Disease Centre, Charing Cross Campus of Imperial College Healthcare NHS Trust, London, United Kingdom.
Mitchell
Hugh D C
HD
Stenman
Ulf-Håkan
UH
Blankenstein
M A
MA
Nustad
Kjell
K
Stieber
Petra
P
Stewart
Wilson
W
Savage
Philip M
PM
Seckl
Michael J
MJ
Braunstein
Glenn D
GD
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
D006063:Chorionic Gonadotropin