Human chorionic gonadotropin (hCG) is a glycoprotein hormone produced by placental trophoblastic cells during pregnancy. It is composed of two subunits, alpha and beta, with the unique beta subunit being the earliest marker of pregnancy. hCG functions to maintain the corpus luteum until 6-8 weeks and stimulate progesterone secretion to support the pregnancy. It also stimulates fetal testosterone production and inhibits maternal immunorejection of the fetus. Normal hCG levels are detectable after 6-8 days and double every two days until 10 weeks, peaking at 10,000 by the second trimester. Abnormally high levels can indicate multiple fetuses, molar pregnancy, or germ cell tumors, while

1. Human chorionic gonadotropin
(hCG)
Omar Aljabri
(Master student in the Department of Laboratories, King
Saud University, Riyadh.)

2. STRUCTURE
hCG is a glycoprotein Molecular weight is 36000-40000 daltons.
The HCG is produced by the placental trophoblastic cells made of two
subunits, alpha, and beta.
α-HCG, produced by cytotrophoblasts, structurally resembles
follicle-stimulating hormone, leutinizing hormone, and thyroid-
stimulating hormone.
β-HCG, made by syncitiotrophoblasts, has a unique structure,
making it the earliest characteristic clinical marker of pregnancy.

4. Function HCG
1. rescue and maintenance of corpus luteum till 6-8 weeks of pregnancy.
2. stimulus for the secretion of progesteron by the corpus luteum.
3. It stimulate Leyding cells of the male fetus to produce testosterone
4. inhibit the maternal process of immunorejection of the fetus as a homograft.
5. Stimulates both adrenal and placental steroidogenesis.
6. Stimulates maternal thyroid because of its thyrotrophic activity.

5. NORMAL LEVEL HCG
Men = < 5.0 mIU/mL
Non Pregnant women = < 5.0
mIU/ mL
1. HCG is detectable after 6 to 8
days.
2. The HCG doubles every two
days until 10 weeks.
3. By second trimester the peak
level is 10,000 (800 ng/mL)

7. High levels of hCG
Multiple Fetuses
Molar pregnancy.
Choriocarcinoma.
Germ cell tumors of ovary and testes
HCG may be produced in primary liver cell carcinoma
Medication

8. Low HCG level
In an early pregnancy as estimated by the last menstrual period.
An ectopic pregnancy
Death of the baby
Miscarriage (spontaneous abortion)