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Alpha-fetoprotein (AFP) is also known as a fetal protein. In adults, it occurs during pregnancy and in the course of certain cancers. We perform the AFP test as confirmation of miscarriage or suspected cancer. The material needed for the test is serum.
What is alpha-fetoprotein (AF)?
Alpha-fetoprotein (AF) characteristics: AFP is a fetal protein that is produced by the gallbladder. Fetal protein occurs during pregnancy (highest at XNUMX weeks; protein levels begin to decline at birth) and in some cancers. The AFP test can also be used as a screening test in a group of people at increased risk of cancer. The effectiveness of the treatment is evidenced by the decrease in the concentration of AFP. After the gallbladder disappears, protein production is taken over by the liver and digestive tract. Alpha-fetoprotein is also secreted by a neoplastic tumor that comes from an embryonic tissue.
Fetal protein testing is useful in monitoring radiochemotherapy and surgery treatments. Its low level means that the treatment is effective, while its rapid growth means that the tumor has recurred or has metastasized. Moreover, thanks to the marking of AF, it is possible to identify possible malformations of the fetus.
When do we perform alpha-fetoprotein (AF) testing?
The indications for the study are listed below.
1. Confirmation of a miscarriage.
2. Suspicion of fetal malformations.
3. The risk of cancer (hepatoblastoma, tumors of the gastrointestinal tract with liver metastases, tumors of the gonads).
4. Monitoring the treatment of gonadal tumors
5. Differentiation of neonatal inflammation and neonatal arthrosis of the biliary tract.
Preparations for the AFP (Alpha-fetoprotein) study
The AFP protein level test does not require any special preparations, as it does not cause complications and there are no contraindications for it. The test involves taking blood after puncturing a superficial vein, usually the ulnar fossa.
- Material for the AF test: serum.
- Preparation for the AF examination: fasting (at least 8 hours).
- The course of the examination: one-time blood sampling from a vein in the arm. The material is collected into a vacuum tube. In children, a small incision is made on the skin with a lancet. The downloaded material is sent further for analysis.
- Waiting time for the test result: 1 day.
- Standards: below 40 µg / l; in pregnant women: first trimester – 10 µg / l, second trimester – 300 µg / l, third trimester – 500 µg / l.
- Notes: Increased concentration of α-fetoprotein is observed in liver cancer, testicular and ovarian germ cell tumors.
The importance of alpha-fetoprotein during pregnancy
As mentioned before, fetal AF increases normally from the 10th week of pregnancy, and its highest level is observed in the 13th week of pregnancy. At the same time, there is a change in the concentration of alpha-fetoprotein in the amniotic fluid. AF is observed in the blood of a pregnant woman with a slight delay (the highest values are noticeable between 32 and 36 weeks of pregnancy). Thanks to the study of the fetal protein, it is possible to determine the condition of the child:
- elevated levels of alpha-fetoprotein in the blood of a pregnant woman – occurs in the case of baby malformations, especially nervous system abnormalities. In addition, it testifies to the threat to the child’s life and the presence of a dead fetus. In some situations, a high AF level indicates a multiple pregnancy;
- low maternal AFu level is characteristic of Down syndrome. Usually, in the first and second trimesters of pregnancy, women are screened by means of fetal ultrasound, triple test and the assessment of PAPP-A and B-hCG levels. However, between 15 and 20 weeks of pregnancy, for the purposes of prenatal diagnosis, the determination of alpha-fetoprotein in a triple test is performed next to B-hCG and estriol. Thanks to these tests, it is possible to diagnose Down’s syndrome and other defects. The sensitivity of this test may exceed 90%.
Alpha-fetoprotein in pregnancy
The determination of alpha-fetoprotein concentration is also important in oncology. Quite often, an increased level of AF indicates a malignant tumor of the liver, ovaries, testes, kidney, colon, lung or stomach. It may also mean that you are developing yolk sac cancer or neuroblastoma. A very high concentration of alpha-fetoprotein is characteristic of patients with liver cancer. The level of AF increases as the tumor grows and then decreases if the treatment is effective. Of course, there are cases where AF does not increase despite the presence of cancer.
Low alpha-fetoprotein values may, in turn, appear in a secondary liver tumor, i.e. with metastasis to another organ. In some cases, AF values below 500 µg / L indicate liver cell damage that is non-neoplastic.
In addition to the above-mentioned situations, other ailments should also be mentioned, for which a high level of AF is characteristic. We are talking about: hepatitis B, hepatitis C, alcoholic cirrhosis and cirrhosis. Patients with these conditions are recommended to have alpha-fetoprotein testing at regular intervals as they are at risk of developing hepatocellular carcinoma.
Thus, the determination of alpha-fetoprotein is performed in order to:
- controlling the effectiveness of treatment,
- monitoring of possible recurrences of liver cancer,
- diagnosis of the disease,
- checking cancer of the testicles and ovaries,
- controlling patients with chronic liver ailments.
Analysis of the AFP research results
Elevated AFP levels can mean: cancer of the gastrointestinal tract (e.g. stomach, colon or pancreas), lung cancer, tyrosinemia (a genetic disease), cirrhosis, hereditary persistence of AFP, ovarian or testicular cancer.
Alpha-fetoprotein is absent:
- in healthy people after the age of 1,
- in women with ovarian adenoma,
- in the chorion,
- in men with testicular seminoma.