Human chorionic gonadotrophin (hCG)
Indications for chorionic gonadotrophin (hCG) test:
- Early diagnosis of pregnancy
- Monitoring the effectiveness of the therapy and diagnosis of recurrence of trophoblastic tumors, testcular or placentar choriocarcinoma, chorioadenoma, seminomas
Human chorionic gonadotrophin (hCG) is a glycoprotein hormone consisting of 2 subunits — α and β, ecovalence related. α-Subunit is identical to α-subunit of luteinizing and follicle-stimulating hormone and pituitary thyrotropin. β-subunit is specific for chorionic gonadotrophin (hCG).
Human chorionic gonadotrophin (hCG) contains neuraminic acid, the amount of which in proportion to its activity: the biological activity of cleavage chorionic gonadotrophin (hCG) disappears. hCG-specific antiserum interacts only with β-subunit.
The norm of human chorionic gonadotrophin (hCG) is not higher than 5 IU/ml in men and nonpregnant women.
Human chorionic gonadotrophin (hCG) is produced physiologically in syncytiotrophoblast of the placenta, it is found in maternal serum at 6-10 days after fertilization and more in 1-2 days in urine. The concentration of chorionic gonadotrophin (hCG) in amniotic fluid correlated with serum, but much less.
The level of chorionic gonadotrophin (hCG) increases until the end of the first trimester of pregnancy, reaching a maximum at 40-80 days, and then decreases. The decrease of chorionic gonadotrophin (hCG) is observed in an ectopic pregnancy and threatened abortion (lower than in normal pregnancy). In men and non-pregnant women increasing the level of chorionic gonadotrophin (hCG) is a reliable sign of malignancy.
Increasing the concentration of chorionic gonadotrophin (hCG) detected at molar pregnancy, choriocarcinoma, seminoma, the ovary and testicles teratoma formation, patients with lung cancer (14% of cases), gastrointestinal tract cancer (60%), genitourinary (30%), colon and rectum cancer (25-77%, depending on the tumor size). Trophoblastic neoplasms both benign and malignant, cause an increasing of chorionic gonadotrophin (hCG) level.
The greatest number of chorionic gonadotrophin (hCG) is produced during chorionepithelioma — the most malignant tumors. It should be noted that, along with high malignancy, chorionepithelioma is one of the few localizations of tumors, which if timely diagnosis and chemotherapy treatment can lead to complete recovery in the absence of metastases (in 95% of cases) and in patients with metastases (in 83%).
The sensitivity of this marker for the testis and placenta carcinomas - 100%, in chorioadenoma - 97%, in non-seminomatous germinomas - 48-86%, and seminoma tumors - 7-14%.
Some tumors produce only single subunit of chorionic gonadotrophin (hCG). It was revealed that in pancreatic adenocarcinoma case are discovered mostly free α-subunit. Chorionic gonadotrophin (hCG) false-positive reactions possible in hemolysis and lipemia.