Comparison of 2 commercially available human chorionic gonadotropin immunoassays used in the management of gestational trophoblastic neoplasia.
OBJECTIVE
To compare serum human chorionic gonadotropin (hCG) titers using 2 commercially available hCG immunoassays in patients with gestational trophoblastic neoplasia (GTN).


METHODS
A total of 213 serum samples from 39 patients with uneventful moles and 697 serum samples from 17 patients with low-risk and high-risk GTN were obtained and subsequently measured with both the hCG C-terminal (hCG-CTP) and DPC Immulite 2000 tests.


RESULTS
In patients with uneventful moles and GTN, serum hCG levels recorded using the hCG-CTP and DPC Immulite 2000 tests correlated well (r2 = 0.936 and r2 = 0.958). However, the serum hCG titers measured using the DPC Immulite 2000 assay were approximately 2.5- and 2.7-fold higher than those measured with the hCG-CTP test (p < 0.0001) when lower titers of hCG (< 40 mIU/mL) were tested. In addition, 3 and 1 patient, respectivelyl, with uneventful mole and GTN obtained positive results with the DPC Immulite 2000 test (3.0-4.2 mIU/mL) after demonstrating undetectable hCG levels with the hCG-CTP test (< 1.0 mIU/mL).


CONCLUSIONS
At the lower levels of hCG, a few discrepancies between hCG titers measured using the 2 commercial immunoassays arose and may be attributed to the existence of hCG-related molecules. However, these hCG metabolites disappeared rapidly, the clinical importance of which remains unclear.
Matsui
Hideo
H
Department of Obstetric and Gynecology, Narita Cross Hospital, 90-1 Iida-cho Narita, Chiba 286-8523, Japan. hmatsui@naritasekijyuji.jp
Kihara
Maki
M
Usui
Hirokazu
H
Tate
Shinichi
S
Mitsuhashi
Akira
A
Shozu
Makio
M
D006063:Chorionic Gonadotropin / Q000097:blood*; D005260:Female; D031901:Gestational Trophoblastic Disease / Q000175:diagnosis*; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation*; D011247:Pregnancy
D006063:Chorionic Gonadotropin