AFP is a glycoprotein that comes from the liver cells of the embryo and disappears from the blood about two weeks after birth.
1.Normal value
Radioimmunoelectrophoresis AFP normal value ≤ 25 μg/L.
Radioimmunoassay AFP normal value: ≤20μg/L.
Enzyme-linked immunoassay AFP normal value: ≤25μg/L.
The most commonly used quantitative test is the radioimmunoassay (normal value 0-25ug/L)
between 25 and 400ug/L is considered low positive.
More than 400ug/L is considered as high concentration positive.
2. Analysis of the causes of high alpha-fetoprotein
① Liver cancer
It is one of the common causes of high fetoprotein. Generally, the content of fetoprotein in normal human serum is less than 20μg/L, but when hepatocellular carcinoma occurs, the function of producing this protein is restored. Therefore, people with liver cirrhosis, chronic hepatitis patients or those with liver cancer in their family should have regular checkups according to their own situation. Therefore, methemoglobin is significant for the early diagnosis of hepatocellular carcinoma.
② Pregnant women and newborns
There is also a transient elevation of AFP because AFP is a normal plasma protein component of the fetus and is the main protein of the early embryo. AFP in pregnant women is significantly elevated, usually in the third month after pregnancy, and by July-August the amount of AFP in maternal blood of pregnant women reaches its peak and is relatively stable, but it is still below 400 μg/L, and gradually after about 3 weeks after delivery It gradually returns to normal level about 3 weeks after delivery.
③ Non-malignant disease
High AFP may be associated with non-malignant diseases such as acute and chronic hepatitis, recovery from severe hepatitis, liver cirrhosis, congenital bile duct occlusion, and malformed fetus, etc. AFP may be elevated, but the magnitude of elevation is relatively small and the duration of elevation is relatively short.
④ Germ cell tumor
According to the data, about 50% of patients with germ cell tumors have positive AFP; some patients with other gastrointestinal tumors such as pancreatic cancer or lung cancer and liver cirrhosis may also have high AFP to varying degrees; in addition, male patients with AFP greater than 25μg/L should also consider the possibility of testicular cancer.
⑤ Viral hepatitis
The difference between chronic hepatitis and hepatocellular carcinoma is that the elevation is low and usually does not increase continuously, but decreases or even returns to normal after treatment.
(6) Neonatal hepatitis
Methemoglobin can be measured in 30% of neonates with hepatitis, and the incidence increases with the severity of the disease, mostly significantly. This can be differentiated from congenital bile duct atresia, in which alpha-fetoprotein is mostly normal.
(7) Other causes
Liver injury, congestive hepatomegaly, ataxia, capillary dilation, congenital tyrosinosis, pregnant women (3-6 months), and embryonal tumors of the testes or ovaries (such as seminoma, malignant teratoma, ovarian cancer, etc.) also often have elevated methemoglobin.
3.Hazards of elevated fetoprotein
① In adults, about 80% of liver cancer patients have elevated fetoprotein in serum, and the rate of positive fetoprotein in germ cell tumors is 50%. Therefore, high AFP generally indicates the development of hepatocellular carcinoma. The level of alpha-fetoprotein in normal human serum is usually less than 20 micrograms per liter, but when liver cells become cancerous, they resume the function of producing this protein, so high alpha-fetoprotein should be considered as a possibility of hepatocellular carcinoma.
② A high AFP in a pregnant woman may indicate a fetal defect. Methemoglobin is found in maternal amniotic fluid or maternal plasma and can be used for prenatal monitoring of the fetus. For example, in neural tube defects, spina bifida, and anencephaly, methemoglobin can enter the amniotic fluid from the open neural tube and cause a significant high methemoglobin in the amniotic fluid. The fetal death in the uterus and congenital defects such as teratoma may also result in high AFP in the amniotic fluid. In 85% of mothers with spina bifida and anencephaly, a high plasma AFP at 16-18 weeks of gestation is diagnostic, but must be combined with clinical experience to avoid false positive errors.
(iii) High methemoglobin may also be caused by liver injury, congestive hepatomegaly, ataxia, capillary dilation, congenital tyrosinosis, pregnancy (3-6 months), or embryonal tumors of the testes or ovaries (e.g., seminoma, malignant teratoma, ovarian cancer, etc.).
Therefore, high methemoglobin is not a good phenomenon for many people and must be brought to the attention of patients to understand the causes of high methemoglobin in combination with medical history and imaging examinations, and to treat it in time to reduce the harm caused by methemoglobin.
4.The relationship between methemoglobin and liver cancer
①Fetoprotein can be regarded as a tumor signal, which means liver cancer may be produced in the liver. Regarding the relationship between fetoprotein and liver cancer, in fact, fetoprotein can be used as an indicator to test liver cancer. However, there is no absolute relationship between the level of AFP and the size of liver cancer. There are two points to note about the relationship between AFP and liver cancer.
First, about one-third of small hepatocellular carcinomas do not have elevated AFP, so a normal AFP does not mean that there is no hepatocellular carcinoma.
Second, hepatitis itself can also cause a slight increase in AFP, and a rise in AFP due to hepatitis means that the damaged liver is regenerating, not that it is complicated by liver cancer. This type of elevated AFP due to hepatitis is usually within the range of 400 (there are exceptions, of course). It is important to note that if the AFP does not decrease after the decrease in ALT and GTR, then the possibility of hepatocellular carcinoma must be considered. In addition, the AFP value in the blood of the pregnant woman will be higher.
②Higher AFP does not indicate a larger tumor. However, if it is in the same patient, the level of AFP (compared with one’s previous value) is quite informative and can be used as an indicator of the success of treatment and whether there is tumor recurrence