Abstract
Background: The free β subunit of human chorionic gonadotropin (free β-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 (Eu3+) chelates only.
Methods: We developed a two-site, one-step assay using two monoclonal antibodies (MAbs) against free β subunit and β subunit with Eu3+ 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 β-hCG concentrations measured using the current assay in 999 maternal serum samples correlated well with those obtained by samarium (Sm3+)-labeled DELFIA free hCGβ assay (r=0.987). The medians for 8–20 weeks for maternal serum free β-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 β-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.
Clin Chem Lab Med 2010;48:109–14.
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