Free Beta-human Chorionic Gonadotropin (β-hCG), Serum

hCG is a glycoprotein composed of two noncovalently linked subunits, α and β, and is produced by syncytio-trophoblast cells of the placenta. The free β-hCG subunit can derive from three sources, direct trophoblast cell production, dissociation of hCG into free α- and free β-subunits, and by macrophage or neutrophil enzymes nicking the hCG molecule. The free β-hCG subunit corresponds to only about 0.3-4% of the total hCG. Total hCG and free β-hCG are the most sensitive single analytes in screening for Down’s syndrome.

In Down’s syndrome, free β-hCG subunit levels are significantly increased during the first trimester. A reasonably efficient screening can be performed as early as between 9 and 15 wks of gestation.

1 ml Serum Stability: 7 Days at 2-8 °C > 7 Days at -20 °C

Avoid grossly haemolysed or grossly lipemic samples. Avoid repeated freeze/thaw cycles.

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