Beta-Human Chorionic Gonadotropin (β-hCG), Serum/Plasma

Human Chorionic Gonadotropin (hCG) is a glycoprotein composed of two noncovalently linked subunits, α and ß, and is produced in large quantities by the syncytio-trophoblast during pregnancy and in the
course of certain malignancies, e.g., molar pregnancy, choriocarcinoma, and testicular cancer. The α-subunit is identical to that of LH, FSH, and TSH. The ß-subunit, however, is hormone-specific. Therefore, antibodies for hCG immunoassays are generally produced against the ß-subunit of hCG so as to overcome problems of cross-reactivity with other glycoprotein hormones. Maternal serum hCG peaks at 8–10 wks and then declines to reach a plateau at 18–20 wks of gestation.

β-hCG is used as a marker of pregnancy. In case of a weak positive result it is advised to take a second sample after 48 Hrs; the doubling time for β-hCG. This test is also useful in helping diagnose ectopic pregnancies, multiple pregnancies and in predicting spontaneous abortion. During the second trimester, it is used along with other parameters, to assess the risk of carrying a child with Down's syndrome and other abnormalities (see Prenatal Maternal Triple and Quadruple Screens). β-hCG is also used as a tumour marker in the case of molar pregnancy, choriocarcinoma, and testicular cancer.

1 ml Serum 1 ml Na2, K3-EDTA or Li, Na, NH4+-Heparin, Sodium Citrate, or Fluoride/Potassium Oxalate Plasma Stability: 3 Days at 2-8 °C 12 Months at -20 °C

Freeze only once. State LMP. Do not test grossly haemolysed samples.

Non-pregnant women: Up to 5.3 mIU/mL Weeks of Gestation: 3 Weeks: 5.8 - 71.2 mIU/mL 4 Weeks: 9.5 - 750 mIU/mL 5 Weeks: 217 - 7138 mIU/mL 6 Weeks: 158 - 31795 mIU/mL 7 Weeks: 3697 - 163563 mIU/mL 8 Weeks: 32065 - 149571 mIU/mL 9 Weeks: 63803 - 151410 mIU/mL 10 Weeks: 46509 - 186977 mIU/mL 12 Weeks: 27832 - 210612 mIU/mL 14 Weeks: 13950 - 62530 mIU/mL 15 Weeks: 12039 - 70971 mIU/mL 16 Weeks: 9040 - 56451 mIU/mL 17 Weeks: 8175 - 55868 mIU/mL 18 Weeks: 8099 - 58176 mIU/mL