HCG in urine and blood: the role of the hormone. How to determine the level of hCG. The norm of hCG in the urine during pregnancy

Women planning a baby try to discern the first signs or symptoms of pregnancy long before they actually should appear. Many expectant mothers begin to do tests almost immediately after the alleged ovulation, so they want to quickly see the treasured two stripes. But today, the most accurate way to determine pregnancy in the early stages is to test for hCG. The growth rate of this hormone is influenced by various factors. We will talk about how hCG in urine increases after conception, in our article. Be sure to dwell on when to start doing pregnancy tests at home and how else you can find out the level of this hormone in the body.

What is hCG?

The full name of this hormone is: chronic human gonadotropin. It begins to be produced by chorionic cells in the first hours of pregnancy - immediately after implantation of the embryo. This usually happens a week after the actual fertilization of the egg.

In its chemical structure, hCG consists of alpha (α) and beta (β) subunits. The latter value is unique to this hormone. It is in the presence of hCG in the blood or urine tests, namely the beta subunit, that implies the implantation of an egg into the uterine wall. This is the basis for home pregnancy tests.

If a woman is not pregnant, chronic gonadotropin is absent in the body. As an exception, it can be produced by various malignant tumors, both in women and in men.

The role of the hormone in the body of a woman

In the normal state, hCG in the urine is absent. But a blood test can show the presence of this hormone in the body, but its concentration is not more than 5 mU / ml. Active growth of hCG occurs on the 6-8th day after fertilization. It plays the following role in a woman’s body:

1. Participates in the development and supports the functionality of the placenta, contributes to an increase in the chorionic villi.
2. It prevents resorption and ensures the activity of the corpus luteum up to 12 weeks of gestation, while the placenta will not independently produce progesterone and estrogen in the required volume. Without these hormones, a successful pregnancy outcome is impossible.
3. Prevents miscarriages in the early stages as a result of a negative reaction of the body to a foreign organism inside the uterus. This is especially true if the Rh factor of the embryo is different from the mother.

The level of hCG should normally correspond to the gestational age. Deviation of the indicator in one direction or another is the reason for a thorough examination of the mother and fetus.

How does hCG increase during pregnancy?

With the successful development of pregnancy, an intensive growth of chorionic gonadotropin is observed in dynamics. From 6-8 days to 11 weeks of gestation, this indicator increases several thousand times, and then gradually decreases. A sharp decrease in the value of the indicator or a slowdown in growth may indicate a miscarriage or an ectopic pregnancy.

An increased level of hCG in the urine may indicate that the woman has not set the gestational age correctly, or may be one of the signs of the following conditions in the body:

• multiple pregnancy (hCG growth above normal is proportional to the number of embryos);
• fetal chromosomal abnormalities (while lowering the plasma protein-A level of PAPP-A);
• with a disease of the future mother with diabetes;
• with the development of late toxicosis (gestosis);
• taking a woman some synthetic hormonal drugs.

Determination of hCG level in the blood

The presence of chorionic gonadotropin in the body can be determined both by urinalysis and by blood analysis. In the first case, the study is most often performed at home with the help of pregnancy tests. Analysis for the determination of hCG in serum is carried out exclusively in the laboratory.

For research, a woman takes blood from a vein on an empty stomach in the morning. The last meal on the eve should be no later than 6 pm. Before taking the test, it is not recommended to drink coffee, tea and other drinks. In addition, the patient is advised to refrain from:

• alcohol
• oily and spicy foods;
• physical activity;
• sexual contact.

If a woman takes any medications, including hormones, she must inform the laboratory assistant about this. The result of the analysis can usually be obtained within two hours after delivery.

Urinary HCG in pregnancy

Analysis to determine the value of chorionic gonadotropin allows you to establish the fact of pregnancy. Its accuracy reaches 98%. This is the easiest pregnancy test. In other cases, it is carried out after an artificial termination of pregnancy, with suspected development of a tumor in the body, dysfunctional bleeding in the uterus.

For analysis, a morning dose of urine is given to the laboratory. The concentration of hCG in it is determined using special reagents. Based on the results of the analysis, one can judge the presence and estimated gestational age. If there are deviations up or down, the doctor should prescribe an additional ultrasound of the pelvic organs and blood donation for hCG.

Preparation for laboratory analysis

Analysis for the determination of hCG in urine can be considered reliable if the following conditions were met before it was performed:

• refusal of sexual activity at least 12 hours before delivery of the material to the laboratory;
• use for the collection of biomaterial sterile container;
• urine delivery to the laboratory within 2 hours after collection.

For analysis, it is necessary to collect an average portion of morning urine. Before this, it is necessary to carry out hygiene procedures, and close the vagina with a swab. This will avoid the secretion in the urine. On the eve of delivery, it is recommended to abandon the use of products that stain the color of biological fluid, such as beets.

The norm of hCG in the urine in the days after ovulation

It is not advisable to take an analysis to detect chorionic gonadotropin in urine earlier than 7 days after the alleged ovulation. Even if fertilization has already occurred, the concentration of the hormone in the body will be too low. On average, on the 8th day, the egg is attached to the walls of the uterus, as a result of which the level of hCG rises sharply. Even the most sensitive tests can determine pregnancy at this time.

How the level of hCG in the urine changes by days, you can find out from the table.

Thus, already in the first week after ovulation, the concentration of homon in the urine increases at least 10 times. On the 42nd day from conception, hCG in the urine can reach 128,000 mU / ml. The highest concentration of the hormone in the urine is usually observed at 8-9 weeks of gestation.

What if the hCG level is below normal?

In such a situation, you should immediately consult a doctor. Low hCG in the urine during pregnancy may mean that the gestational age is incorrect. A gynecologist will examine the patient and give direction to an ultrasound examination. This will allow you to evaluate which week of gestation corresponds to the development of the embryo. Perhaps ovulation was late and, therefore, fertilization occurred a few days later than the expected date. In this case, the ultrasound will show that the woman has absolutely no need to worry.

In addition to the incorrect determination of the gestational age, a low level of hCG can also indicate serious violations in the body:

• ectopic pregnancy;
• anembryony;
• intrauterine growth retardation;
• the threat of spontaneous abortion;
• placental insufficiency;
• fetal death of the fetus (after 24 weeks of gestation).

If the reason for the decrease in chorionic gonadotropin is the threat of spontaneous abortion, the doctor prescribes hormone therapy to the woman, which increases the chances of the embryo to survive.

Determination of hCG at home

To find out if there is a pregnancy or not, it is not necessary to run to the laboratory. This can be done at home. The detection of the hCG beta subunit in the body is based on special pregnancy tests. They have different sensitivity (from 10 mU / ml and higher). Thus, if you start from the data in the table above, pregnancy can be detected even before the delay of menstruation, starting from day 7 after ovulation.

At the heart of every pregnancy test is the reaction of the reagent with urine. If the hCG hormone is present in the body, the reagent will react by the appearance of a second strip on the test. In the early stages of pregnancy, false-negative results are possible. This happens when implantation has already occurred, and the test does not show the second strip. In fact, you do not need to be upset in advance. It is possible that ovulation occurred later, and the sensitivity of the test is too high to determine an early pregnancy. For this reason, doctors do not recommend performing home tests until menstruation is delayed.

Pregnancy tests

The pharmaceutical industry offers consumers several types of home tests:

1. Stripes. This is the simplest and most affordable test model. A hCG sensitive reagent is applied to one side of such a strip. When performing the test, it should be lowered into a jar of morning urine to the indicated level, and then put on a flat surface. You can evaluate the result in 5 minutes.
2. Jet. Such a test does not need to be lowered into a container with urine, it is enough to substitute it under the stream during morning urination.
3. Electronic (digital) test. It has the highest sensitivity and can show a pregnancy for a period of 1-2 weeks (7-14 days after ovulation). The test result can be seen on the scoreboard.

It is worth noting that hCG in the urine by the day does not show any of the tests presented. The most accurate result can be obtained only after passing laboratory tests.