Determination of median levels of the free beta subunit of human chorionic gonadotropin in women from Mainland China using a new time-resolved fluoroimmunoassay.
BACKGROUND
The free beta subunit of human chorionic gonadotropin (free beta-hCG) is an important serum marker for biochemical screening. Its weekly median value varies with ethnicity. Most of the fluorometers for lanthanide chelates are designed for the detection of signals from europium (Eu(3+)) chelates only.


METHODS
We developed a two-site, one-step assay using two monoclonal antibodies (MAbs) against free beta subunit and beta subunit with Eu(3+) chelates as labels. Using the present assay, we evaluated 24,634 normal serum samples in Chinese pregnant women during 8-20 weeks of gestation.


RESULTS
The detection limit using this assay was <0.05 ng/mL. The within-run and between-run imprecision was <6.0% and 7.0% using control material. Free beta-hCG concentrations measured using the current assay in 999 maternal serum samples correlated well with those obtained by samarium (Sm(3+))-labeled DELFIA free hCGbeta assay (r=0.987). The medians for 8-20 weeks for maternal serum free beta-hCG were higher in the women from mainland China compared to reports from other countries.


CONCLUSIONS
The present assay is suitable for use in biochemical screening of women in mainland China. Our study on the median concentrations of free beta-hCG will help establish reference values that are specific for ethnic populations from the Chinese mainland. These will be useful for studying the importance of ethnic factors in biochemical screening.
Tang
Yong-Ping
YP
School of Biotechnology, Southern Medical University, Guangzhou, Guangdong Province, PR China.
Wu
Ying-Song
YS
Yin
Ai-Hua
AH
Xu
Wei-Wen
WW
Yuan
Peng-Hui
PH
Li
Ming
M
D002681:China; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood*; D003429:Cross Reactions; D005063:Europium / Q000737:chemistry; D005260:Female; D015200:Fluoroimmunoassay / Q000379:methods*; D005865:Gestational Age; D006801:Humans; D057230:Limit of Detection; D011247:Pregnancy; D012016:Reference Values; D013997:Time Factors
D018997:Chorionic Gonadotropin, beta Subunit, Human; D005063:Europium