HCG (human chorionic gonadotropin) is often called the “pregnancy hormone”, because it is responsible for the regulation of hormonal processes in the female body during the period of gestation. Due to HCG pregnancy test a woman may easily find out whether she is pregnant. However, HCG blood test is prescribed not only to women, but also to men. So, what is HCG test and why is it useful?
HCG: Its Role in the Body and the Essence of the Test
Human chorionic gonadotropin is a hormone that is produced by a component of a fertilized egg – plasmodiotrophoblast. After implantation to the wall of the uterus, HCG stimulates the development of the placenta. But one should know that this hormone is also produced in cancerous diseases (both in women and men). So, the HCG analysis is also used to diagnose oncology. The question of whether HCG is the cause or consequence of cancer remains open. Therefore, in some countries it is illegal to sell drugs for homeopathic and dietary preparations containing HCG without doctor’s prescription.
HCG consists of alpha (a) and beta (b) units. The first one is identical to luteinizing and thyroid-stimulating hormone; the second one is unique for human chorionic gonadotropin. Therefore, its indicators are of decisive importance in laboratory analysis. In plasma, the beta-unit is detected approximately 6-8 days after the fertilization has occurred. After 7 days after delivery, the chorionic gonadotropin should no longer be found in urine and blood.
HCG Performs the Following Functions:
- contributes to the preservation of the yellow body; accelerates the production of progesterone and estrogen – in the first weeks of pregnancy;
- stimulates the function of the sexual glands and adrenal glands in the fetus;
- prepares the mother’s immune system;
- stimulates Leydig cells that produce testosterone in male embryos.
An increase in HCG may indicate pregnancy, but an increase in hormone concentration also indicates an abnormality of the fetus, diabetes in the mother or even cancer. Comparing the hormone levels at different periods of pregnancy, the doctor can identify an ectopic pregnancy.
In men, an increase in the level of this hormone can be triggered by tumours, including teratoma and pulpy testis. Decrease of the level of HCG is also fraught with consequences. Its indicators differ in different categories of patients.
Types of HCG Analyzes
In medical practice, two analyzes on HCG are known: the determination of total HCG and the determination of free beta-HCG. They are used for different purposes.
A total blood HCG test is used for early diagnosis of pregnancy, when an urine test is not yet able to determine the result. In the absence of pathologies, the level of the hormone in the first weeks of pregnancy is doubled every 2 days. The maximum is reached by 10-11 weeks. Then the concentration of HCG gradually decreases.
In the second trimester of pregnancy, the total HCG analysis is administered as part of prenatal screening, the so-called triple or quadruple test.
Free b-HCG Blood Test
Such an analysis is indicative in the diagnosis of trophoblastic (molar pregnancy, chorionic carcinoma) and testicular (oncology of testicles) neoplasms.
In addition, it is used in the screening of the first and second trimester of pregnancy to assess the risk of Down’s and Edwards’ syndrome in the fetus. A positive result of the analysis puts a woman at risk. At the same time, it is not an absolute indicator of the development of chromosomal abnormalities of the fetus. Pregnant women are advised to make free beta-HCG test at 8-13 and 15-20 weeks. Age over 35 years old, Down’s disease in the anamnesis, congenital malformations and hereditary diseases in close relatives, irradiation are special indications for the purpose of the HCG pregnancy test.
Early Diagnosis of Pregnancy: Determining the Level of HCG
What is HCG?
HCG (human chorionic gonadotropin) is a special hormone of pregnancy, which is an important indicator of the development of pregnancy and its deviations. Chorionic gonadotropin produces chorion cells (embryonic membranes) immediately after its attachment to the uterine wall. Based on the HCG pregnancy test, the doctor determines the presence of chorionic tissue in the body, and hence, the onset of pregnancy in a woman.
When Can HCG Pregnancy Test Be Done?
The level of chorionic gonadotropin in the blood is the most reliable method of determining pregnancy in the early stages. Chorionic gonadotropin appears in the body of a woman from 5 to 6 days after fertilization. A common rapid test for pregnancy, which every woman can use at home, is also based on the presence of chorionic gonadotropin in the urine. Still, the required level of this hormone in the urine to diagnose pregnancy is reached a few days later.
In the absence of any pathology, during the first weeks of pregnancy the hormone level doubles every 2 days. Its maximum concentration is reached by 10-11 weeks of pregnancy. After 11 weeks, the level of the hormone gradually decreases.
An increase in the level of chorionic gonadotropin during pregnancy can occur in the following cases:
- multiple pregnancy;
- toxicosis, gestosis;
- diabetes in the mother;
- pathologies of the fetus, Down’s syndrome, multiple developmental defects;
- incorrectly established term of pregnancy;
- reception of synthetic gestogens, etc.
High HCG values can also be seen within a week after the abortion procedure. A high level of hormone after a mini-abortion indicates a progressive pregnancy.
A low level of chorionic gonadotropin in pregnancy can mean the wrong setting of the gestational age or be a sign of serious violations such as:
- ectopic pregnancy;
- undeveloped pregnancy;
- delay in fetal development;
- the threat of spontaneous abortion;
- chronic placental insufficiency;
- fetal death (in the II-III trimester of pregnancy).
According to the results of HCG pregnancy test it is possible to determine the presence of some abnormalities of fetal development, but the exact diagnosis cannot be made. The study only reveals women who are at risk. In this case, women will need to make a serious additional examination.
What Role Does HCG Hormone Play in the Human Body?
Apart from determining pregnancy, the level of this hormone can show the nature of the course of pregnancy and the presence of multiple pregnancies.
The most important task of the chorionic gonadotropin is to maintain the pregnancy itself. Under its control, the main hormones of pregnancy are synthesized: estrogen and progesterone. In the first trimester, until the placenta is fully formed (up to 16 weeks), the chorionic gonadotropin maintains the normal functional activity of the yellow body, namely, the production of progesterone.
Another important function of chorionic gonadotropin is to stimulate ovulation and maintain the vitality of the yellow body.
When Does the Doctor Prescribe HCG Test?
It’s clear that HCG pregnancy test is used for detecting pregnancy. But HCG level is also useful for the following:
- for the detection of amenorrhea;
- exclusion of the possibility of ectopic pregnancy;
- assessment of the completeness of induced abortion;
- for the dynamic observation of pregnancy;
- when there is a threat of miscarriage and suspicion of an undeveloped pregnancy;
- for the diagnosis of tumors – chorionepithelioma, molar pregnancy;
- for prenatal diagnosis of malformations of the fetus.
- for diagnosis of testicular tumors.
How to Pass the HCG Pregnancy Test Correctly?
For the HCG pregnancy test the doctor takes the blood from the vein, preferably in the morning and on an empty stomach. The laboratory test is recommended not earlier than 4-5 days of menstruation delay. It can also be repeated after 2-3 days to clarify the results. To identify the pathology of the fetus in pregnant women, HCG blood test should be repeated from 14 to 18 weeks of pregnancy.
In the complex diagnosis of malformations of the fetus, it is also recommended to pass tests for the determination of the following markers: AFP (alpha-fetoprotein), E3 (unconjugated oestriol), and ultrasound.
HCG Pregnancy Test or Urine Test? What Is Better?
Pregnancy tests from pharmacies really help a lot in such an important matter as clarifying the fact of pregnancy. At the same time, they can’t determine the level of HCG in the blood. You can only indirectly judge about the increase in the level of this hormone.
In addition, HCG pregnancy test allows you to learn about pregnancy much earlier than an ordinary pregnancy test.
The fact is that by making a pregnancy test, we actually determine whether there is an increase in HCG in the urine. At the same time we have no idea about its level in our blood. Thus, we cannot be sure about the duration of pregnancy with such an ordinary test.
But that’s not all. Due to HCG pregnancy test, we know the exact level of the hormone in the blood. Since the increase in the level of HCG in the blood begins to occur much earlier than a similar increase in the urine of a woman, it is possible to clarify the fact of pregnancy with HCG pregnancy test much faster.
In other words, HCG pregnancy test gives us the correct answer a few days earlier than the test from the pharmacy.