Human Choionic Gonadotophin (HCG) is one of the earliest molecular substances secreted by human embryonic cells. It is a glycoprotein synthesized by syncytiotrophoblastic cells and secreted into maternal blood during pregnancy. It is composed of two subunits, α and β, of which α-peptide chain is similar to the α chain of LH, FSH and TSH, while β-peptide chain is specific. Its molecular weight is about 47,000, mainly found in blood, urine, colostrum, amniotic fluid and fetal body.

The main function of HCG is to stimulate the corpus luteum from the menstrual corpus luteum to the corpus luteum of pregnancy, while promoting the continuous secretion of estrogen and progesterone, maintaining the endometrial morphology, promoting the formation of decidua, and making the placenta grow and mature, which is crucial for maintaining pregnancy.

With the increase of the gestational week, HCG can be excreted into the urine through the blood circulation of pregnant women, so after pregnancy, the blood and urine will contain HCG. Therefore, there are two detection methods of blood HCG and urine HCG for Pregnancy Test.

So, how to choose blood HCG and urine HCG? What clinical significance does HCG have in addition to determining pregnancy?

Blood HCG and urine HCG, how should I choose?

From the convenience of inspection:

1.The Ivd Pregnancy Test Strips and stick required for urine HCG detection can be bought at the pharmacy. The detection method is simple and easy to operate, and the waiting time for knowing the result is relatively short.
2.Blood HCG needs to go to the hospital for blood test, which is not as convenient and easy to operate as urine HCG detection in general.

 

From the time of detection:

1.Urine HCG must be tested after 7 to 10 days of delayed menstruation, too early detection even if pregnant, because the HCG content in the urine rises slowly, the test paper can not respond to it, and may test negative (no pregnancy).
2.After the female conception, the blood β-HCG can be measured from the 9th to 11th day of fertilization, and the value is increased quickly in the first eight weeks of pregnancy. In other words, the blood HCG test is often detected one to two days after menopause, so that the time to confirm pregnancy can be advanced, and the corresponding preparation and countermeasures for pregnancy can be made earlier.

 

In terms of accuracy:

1.In addition to intact HCG in urine, there are many free β-HCG and its degraded fragments. The concentration of HCG in urine is related to the degree of urine concentration, and the higher the concentration, the higher the concentration of HCG, such as morning urine. Most of them are qualitative tests, and the results are judged by the naked eye, which is greatly affected by personal factors.
2.Blood HCG is mostly quantitative detection, with specific values. Through continuous monitoring, it can be distinguished from slight elevation of HCG during menstruation, non-specific elevation caused by pituitary and other lesions, ectopic pregnancy and early abortion. Qualitative urine HCG does not do this. So blood HCG is more accurate.

 

From the sense of detection:

1.Urinary HCG is only used for preliminary determination of pregnancy.
2.In addition to the judgment of Ivd early pregnancy test, blood HCG value can also be comprehensively analyzed in combination with clinical conditions and other examination results to obtain a correct judgment for multiple pregnancy, ectopic pregnancy, abnormal embryo development delay, mole, some endocrine diseases or tumors.

In addition, blood HCG values are generally higher than urine HCG values in pregnant women. In the process of detection, urine HCG is affected by many factors, such as concentration dilution caused by too much drinking water, and alcohol may also be affected, so the accuracy of blood HCG quantitative detection is better than that of urine HCG quantitative detection.

Therefore, in the detection of HCG, serum samples should be the main, urine samples as a supplement. It is recommended that after determining urine HCG (such as using early pregnancy test strips), go to the hospital as soon as possible to do blood HCG determination to make a clear diagnosis.

Clinical significance of HCG

1.Distinguish between normal and abnormal pregnancy

Based on normal HCG concentration changes, 79% of pregnancies are carried to term if the first HCG is within the normal range, and 92% of pregnancies fail if the first HCG is below normal.

In particular, ectopic pregnancy is often due to insufficient blood supply at the bed point, resulting in dysplasia of trophoblast cells, less HCG secretion, and lower than normal levels.

2.Diagnosis and treatment of abortion

Incomplete abortion, there is still placental tissue in the uterus, HCG qualitative positive, complete abortion or stillbirth HCG can be negative.

If HCG is below 2500 IU/L and gradually decreases, there is a possibility of miscarriage or stillbirth; When it is reduced to 600 IU/L, abortion is inevitable, such as the continuous decline of HCG in the blood, indicating that the abortion is ineffective, and on the contrary, it indicates that the abortion is successful.

Serum HCG should return to normal 4 days after delivery or 13 days after abortion. If this is not the case, the possibility of an anomaly should be considered.

3.Malignant mole, chorionic epithelial carcinoma and male testicular teratoma

In this case, HCG is abnormally elevated. After surgical treatment, if the treatment is effective, HCG gradually decreases to normal level. If HCG does not decrease but increases or maintains a high value, it indicates that the treatment is ineffective or relapses.

4.Others

In pregnancy hypertension, HCG is often high; HCG is generally higher in multiple pregnancies than in single pregnancies.

It is worth noting that HCG detection is not only applicable to women, the human body will secrete trace amounts of HCG regardless of women and men, regardless of pregnancy. Therefore, men may also need to be tested for HCG in some cases.

In some specific diseases, such as testicular cancer and yolk sac tumor, HCG levels may be elevated, and a positive result may appear when tested with an early pregnancy test. However, urinary HCG tests cannot be used to screen for testicular cancer, and the biggest problem is missed detection because only 20-30% of patients with testicular cancer have elevated HCG levels.

At the same time, in addition to testicular cancer, other neoplastic diseases or some unknown causes may also cause elevated HCG levels, so the diagnosis of testicular cancer cannot be completely based on urine HCG.

 

HCG Reference value:

male

< 0.5-2.43 mIU/ml

Non-pregnant woman

< 0.5-3.81 mIU/ml

Pregnant woman

0.2-1 week 5-50mIU/ml

1-2 weeks 50-500mIU/ml

2-3 weeks 100-5000mIU/ml

3-4 weeks 500-10000 mIU/ml

4-5 weeks 1000-50000mIU/ml

5-10 weeks 10000-100000 mIU/ml

6-8 weeks 15000-200000 mIU/ml

8-12 weeks 10,000-100,000 mIU/ml