title: Determination of median levels of the free beta subunit of human chorionic gonadotropin in women from Mainland China using a new time-resolved fluoroimmunoassay.
abstract: 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.
authors: School of Biotechnology, Southern Medical University, Guangzhou, Guangdong Province, PR China.
authors: Yong-Ping
authors: YP
authors: Tang
authors: Ying-Song
authors: YS
authors: Wu
authors: Ai-Hua
authors: AH
authors: Yin
authors: Wei-Wen
authors: WW
authors: Xu
authors: Peng-Hui
authors: PH
authors: Yuan
authors: Ming
authors: M
authors: Li
mesh_terms: 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
chemical_list: D018997:Chorionic Gonadotropin, beta Subunit, Human; D005063:Europium