Beta-chorionic gonadotropin in blood

Reference values (norm) for the concentration of beta-chorionic gonadotropin in the blood serum: adults - up to 5 IU/ml; during pregnancy 7-10 days - more than 15 IU/ml, 30 days - 100-5000 IU/ml, 10 weeks - 50,000-140,000 IU/ml, 16 weeks - 10,000-50,000 IU/ml. Half-life is on average 2.8 days.

Human chorionic gonadotropin is a hormone consisting of two subunits, alpha and beta, non-covalently linked to each other; the alpha subunit is identical to the alpha subunit of LH, FSH and TSH, the beta subunit is specific to human chorionic gonadotropin.

Beta-chorionic gonadotropin is a glycoprotein secreted by the syncytial layer of the trophoblast during pregnancy. It maintains the activity and existence of the corpus luteum, stimulates the development of the embryoblast. It is excreted in the urine. Detection of beta-chorionic gonadotropin in the blood serum is a method for early diagnosis of pregnancy and pathology of its development. In oncology, the determination of beta-chorionic gonadotropin is used to monitor the treatment of trophoblastic and germ cell tumors. The half-life of beta-chorionic gonadotropin is 3 days. In men and non-pregnant women, a pathological increase in the concentration of beta-chorionic gonadotropin is a sign of a malignant tumor.

Diseases and conditions in which the concentration of beta-chorionic gonadotropin in the blood changes

Increased concentration

• Pregnancy
• Germ cell tumors (chorionepithelioma)
• Hydatidiform mole
• Fetal neural tube defects, Down syndrome
• In case of incomplete removal of the fertilized egg during an abortion
• Trophoblastic tumor
• Testicular teratoma
• Multiple pregnancy
• Menopause
• Endocrine disorders
• Seminoma

Decreased concentration

• A decrease in concentration relative to the pregnancy phase indicates the presence of:
  • ectopic pregnancy;
  • damage to the placenta during
  • pregnancy;
  • threat of miscarriage

The sensitivity of β-hCG determination in blood in ovarian and placental carcinoma is 100%, in chorionadenoma - 97%, in non-seminomatous germinomas - 48-86%, in seminoma - 7-14%. Increased concentration of β-chorionic gonadotropin is observed in 100% of patients with trophoblast tumors and in 70% of patients with non-seminomatous testicular tumors containing syncytiotrophoblast elements.

Testicular germinomas are among the most common oncological diseases in young men (20-34 years). Since the histological type of the tumor may change during therapy, it is recommended to perform a combined determination of β-CG and AFP in germinomas. Seminomas, dysgerminomas and differentiated teratomas are always AFP-negative, pure yolk sac tumors are always AFP-positive, while carcinomas or combined tumors, depending on the mass of endodermal structures, can be either AFP-positive or AFP-negative. Thus, for germinomas, β-CG is a more important marker than AFP. Combined determination of AFP and β-CG is especially indicated during the treatment of germinomas. The profiles of these two markers may not coincide. The AFP concentration decreases to normal values within 5 days after radical surgery, reflecting a decrease in the total tumor mass. After chemotherapy or radiotherapy, on the contrary, the AFP concentration will reflect only a decrease in the number of AFP-producing cells, and since the cellular composition of germinomas is mixed, the determination of β-CG is necessary to assess the effectiveness of therapy.

The combined determination of AFP and β-hCG allows achieving a sensitivity of 86% in the diagnosis of relapses of non-seminomatous testicular tumors. An increasing concentration of AFP and/or β-hCG indicates (often several months earlier than other diagnostic methods) tumor progression and, therefore, the need to change treatment. Initially high values of AFP and β-hCG in the blood indicate a poor prognosis.

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