Human Chorionic Gonadotropin (hCG)

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Background

Human chorionic gonadotropin (hCG) is the basis for all pregnancy tests.1 It is mainly produced by the syncytiotrophoblast cells of the placenta during pregnancy and can also be seen in gestational trophoblastic diseases (choriocarcinoma, hydatidiform mole) and testicular germ cell malignancies.1,2,3,7 It has been shown that the hCG produced through the majority of normal pregnancy is a smaller molecule than the hCG produced in choriocarcinomas and malignancies, due to four double sized O-linked oligosaccharide side chains of the molecule.8 Lesser differences are also found on the N-linked oligosaccharides.8 This larger molecule is named choriocarcinoma hCG, or hyperglycosylated hCG (hCG-H).

hCG-H is a cytokine-like molecule3 produced by stem cytotrophoblast cells, which are invasive cells that are active during implantation of the blastocyst in pregnancy.1,2,3 A monoclonal antibody (antibody B152) has been generated that has 0% cross-reactivity with regular hCG.9 An automated chemiluminescence assay is now marketed by Nichols Institute Diagnostics using B152 and an anti-β tracer antibody.3 This allows us to determine the immunoreactivity of hCG-H in urine and serum samples. Many studies have now shown hCG-H to be the most predominant form of hCG in early pregnancy. 1,3,4,5,6

Since there is such as high proportion of hCG-H in the first weeks of pregnancy, it is being studied to determine its significance as a marker of early pregnancy. This paper will review studies determining the effectiveness of using hCG-H to monitor pregnancy outcome, as well as studies researching the sensitivities of commercial pregnancy tests to hCG-H.

Scope of literature review

Research for this literature review was done using Web of ...

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...For pregnancy detection, companies producing at home detection tests may want to incorporate detection of hCG-H for greater accuracy in their results. This would allow for optimal detection of pregnancy even before the time of missed menses. For hCG-H testing to be used to clinically determine pregnancy outcome, other laboratories would need to evaluate their own set of data to be able to properly determine if the 13ug/L cut off point found by Sutton-Riley et al. (2006) is viable. Studies would have to take many factors into account including age, race, overall health, and so on, to properly determine what normal values are. Detecting hyperglycosylated human chorionic gonadotropin is changing the way we now look at pregnancies and pregnancy loss. With further research, its full applications in pregnancy outcome and detection are becoming closer to being realized.
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