Alpha fetoprotein. AFP analysis during pregnancy and in other cases.

Reference values

For children, men and non-pregnant women, normal values ​​are presented in the table.

For pregnant women, depending on the stage of pregnancy, normal values ​​are presented in the table.

Alpha-fetoprotein refers to the so-called embryonic proteins, which are synthesized by embryonic cells.
AFP performs many important functions, ensuring the full development of the fetus. Alpha-fetoprotein enters the blood of a pregnant woman through the placenta (the “baby place” that forms during pregnancy and connects the mother and fetus, providing the baby with essential nutrients) and from the amniotic fluid (amniotic fluid, which plays an important role in the metabolism of nutrients and fetal protection). Accordingly, with an increase in the concentration of fetal alpha-fetoprotein, its values ​​in the mother’s blood increase, increasing from the 10th week of pregnancy and reaching maximum values ​​by the 32-34th week. Alpha-fetoprotein testing in pregnant women is carried out as part of a “triple test” together with hCG (human chorionic gonadotropin) and E3 (free estriol) in the second trimester of pregnancy (between 15 and 20 weeks) to identify the risk of abnormal development of the fetus.

An embryonic protein that indicates the condition of the fetus during pregnancy and is a tumor marker for an adult.

Synonyms Russian

AFP.

English synonyms

Alfa-Fetoprotein, AFP, Maternal Serum Alpha-Fetoprotein (MS-AFP), AFP Tumor Marker.

Research method

Solid-phase chemiluminescent enzyme-linked immunosorbent assay (“sandwich” method).

Determination range: 0.5 - 50000 IU/ml.

Units

IU/ml (international unit per milliliter).

What biomaterial can be used for research?

Venous blood.

How to properly prepare for research?

• Do not smoke for 30 minutes before the test.

General information about the study

Alpha-fetoprotein is a glycoprotein that is produced in the fetal yolk sac, liver and intestinal epithelium of the fetus. The molecular weight of the protein is about 70,000 daltons, its half-life is 5-7 days. In the fetal body, it performs the functions of adult albumin: it transports certain substances necessary for the development of the fetus, binds estrogens, limiting their effect on the developing body, and protects against the negative effects of the mother’s immune system.

Alpha-fetoprotein takes an active part in the full development of the fetus, and its level should correspond to gestational age (the age of the fetus from the moment of fertilization). The maximum content of this protein in the blood and amniotic fluid of the fetus is observed at the 13th week, and in the mother’s blood it gradually increases from the 10th week of pregnancy and reaches a maximum at 30-32 weeks. 8-12 months after birth, the level of AFP in the child’s blood decreases to a trace amount, as in adults.

Alpha-fetoprotein enters the mother's body through the placenta. Its level depends on the condition of the gastrointestinal tract, fetal kidneys and placental barrier. In this regard, AFP is used as a nonspecific marker of fetal condition and obstetric pathology. Combined tests for AFP, human chorionic gonadotropin and estriol (the so-called triple test) at 15-20 weeks of pregnancy are used to check the fetus for developmental defects and chromosomal abnormalities, but are not absolute indicators of pathology or normal fetal development. In this case, it is very important to know exactly the gestational age of the fetus, since the level of AFP in the blood differs at different weeks of pregnancy.

In the adult body, alpha-fetoprotein is absent or found in minimal quantities. A moderate increase in its level can be caused by liver pathology, and a significant increase can be caused by a poorly differentiated tumor - this is due to the fact that some cancerous tumors acquire the properties of embryonic tissues and, accordingly, the ability to synthesize proteins that are characteristic of the early stages of development of the body. A sharp increase in AFP is mainly detected in cancer of the liver and gonads.

In primary hepatocellular carcinoma, an increase in AFP in half of the patients can be detected 1-3 months before the clinical manifestations of the disease. Although the size of the tumor, the intensity of growth, the stage of the process and the degree of malignancy are not proportional to the amount of alpha-fetoprotein in the blood. With progressive germ cell nonseminoma (tumor of the gonads), determining the level of AFP and human chorionic gonadotropin is important for assessing the chances of survival of patients.

What is the research used for?

• For prenatal diagnosis of pathologies of fetal development: disorders of the neural tube, anencephaly (severe developmental defect in which the fetus is missing part of the brain), chromosomal abnormalities.
• To detect primary hepatocellular carcinoma (liver cancer).
• To detect testicular teratoblastoma (germ cell nonseminoma).
• For the diagnosis of poorly differentiated tumors.
• For the diagnosis of metastases of tumors of various localizations in the liver.
• To evaluate the effectiveness of treatment for certain cancers and to monitor their course.

When is the study scheduled?

• When examining a patient with a high risk of developing a tumor (liver cirrhosis, chronic hepatitis, alpha-antitrypsin deficiency).
• If tumor metastasis to the liver is suspected.
• When examining a patient with a neoplasm of the gonads.
• Before, during and after treatment for certain cancers.
• When monitoring the condition in the postoperative period of patients who had a tumor removed.
• In the second trimester of pregnancy (between the 15th and 21st weeks of gestation).
• When examining pregnant women who underwent amniocentesis and chorionic villus sampling in early pregnancy.

What do the results mean?

Reference values

Causes of increased alpha-fetoprotein levels

Oncological diseases:

• hepatocellular carcinoma (liver cancer) (in 70-95% of cases),
• germ cell nonseminoma (testicular cancer),
• liver metastases (in 9%),
• tumors of other localizations (lung, intestinal, stomach, kidney, breast, pancreas cancer),
• embryonal tumors (teratomas).

Other pathological conditions:

• acute or chronic active hepatitis (moderate and short-term increase in the rate),
• primary biliary cirrhosis,
• alcoholic liver disease,
• liver injury (or surgery),
• congenital tyrosinemia,
• ataxia-telangiectasia,
• Wiskott–Aldrich syndrome.

Obstetric pathology:

• fetal neural tube defects (spina bifida, anecephaly) (80-90%),

• developmental disorder of the urinary system (congenital nephrosis, polycystic kidney disease, absence of a kidney, obstruction),
• atresia of the esophagus or intestines,
• umbilical hernia,
• gastroschisis (defect of the anterior abdominal wall),
• fetal teratoma,
• cystic hygroma,
• hydrocephalus,
• fetal distress,
• threatened abortion,
• pathology of the placenta,
• multiple pregnancy,
• incomplete osteogenesis.

Reasons for low alpha-fetoprotein levels:

• Down syndrome (trisomy 21),
• Edwards syndrome (trisomy 18 chromosome),
• Patau syndrome (trisomy 13 chromosome),
• intrauterine fetal death,
• hydatidiform mole,
• pregnancy obesity.

A decrease in AFP levels after tumor removal is considered a favorable sign and indicates the effectiveness of treatment.

What can influence the result?

• The patient's use of monoclonal antibody medications may change the test result.
• Among representatives of the Negroid race, maternal AFP is 10-15% higher than the average, while among Mongoloids it is lower.
• Insulin-dependent diabetes leads to a decrease in AFP in the blood of a pregnant woman.

Important Notes

• To use the test in diagnosing obstetric pathology, it is necessary to accurately know the gestational age of the fetus. The level of alpha-fetoprotein alone cannot serve as a criterion for diagnosing fetal development disorders. If deviations in ACE levels are detected, it is necessary to comprehensively examine the pregnant woman using ultrasound diagnostics and other laboratory methods.
• If the AFP level is elevated in a pregnant woman and there are no pathological changes on ultrasound and amniocentesis, it is necessary to keep in mind the high likelihood of developing disorders (for example, premature birth, low birth weight of the child, fetal death).
• The use of AFP for cancer screening in the general population is not recommended.
• Patients taking high doses of biotin (>5 mg/day) should be tested no earlier than 8 hours after taking the drug.

Reasons for the decrease in alpha-fetoprotein in the blood of pregnant women

• Down syndrome in the fetus,
• delayed fetal development,
• fetal death
• false pregnancy.

AFP is used as a tumor marker in adult men and non-pregnant women.
As the tumor process develops, cancer cells begin to synthesize alpha-fetoprotein, so an increase in its concentration in the blood indicates the presence of a malignant neoplasm. Alpha-fetoprotein was first described as a human tumor-associated protein in 1964. It was then discovered that elevations of alpha-fetoprotein above the values ​​typically found in healthy individuals occur in several malignant diseases such as testicular cancer, liver cancer (primary hepatocellular carcinoma), with metastases of other tumors to the liver.

Patients with liver cirrhosis (a disorder of the liver structure, manifested by functional failure), chronic hepatitis B and C are at risk of developing liver cancer. The determination of alpha-fetoprotein in them is of great practical importance.

The level of alpha-fetoprotein in liver cancer and testicular cancer well reflects the dynamics of therapy. A significant decrease in alpha-fetoprotein after chemotherapy indicates the effectiveness of treatment.

Sources:

1. Rodriguez-Diaz JL, Rosas-Camargo V, Vega-Vega O, Morales-Espinosa D, Mendez-Reguera A, Martínez-Tlahuel JL, et al. Clinical and pathological factors associated with the development of hepatocellular carcinoma in patients with hepatitis virus-related cirrhosis: a long-term follow-up study. Clin Oncol (R Coll Radiol) 2007; 19:197-203.
2. Chereshnev V.A., Rodionov S.Yu., Cherkasov V.A., Malyutina N.N., Orlov O.A. Alpha fetoprotein. Ekaterinburg: Ural Branch of the Russian Academy of Sciences, 2004. 376 p.
3. N. Salesi, B. Di Cocco, F. Alghisi, F. Calabretta, G. Bossone. Testis cancer markers. Clinical use. Minerva Med. 2002 Oct; 93(5):365-9.

3.How to prepare and how is the analysis carried out?

How to prepare for an AFP test

You do not need to prepare before your AFP test.

Pregnant women are weighed because... Test results also depend on weight. They also vary by age, gestational age, and race.

How is AFP analysis performed?

An AFP test is performed after taking blood from a vein. Blood sampling from a vein is carried out according to a standard procedure.

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Indications for examination

Knowing that the AFP tumor marker is a protein formation that helps to identify a dangerous pathology long before its clinical detection and the manifestation of any symptoms, in some cases you should undergo an examination.
The main indications for testing for cancer markers are:

• Genetic predisposition to cancer.
• Chronic liver diseases, hepatitis of all types, symptoms of cirrhosis.
• Suspicions of the presence of seals in the body.
• Precancerous conditions.
• Detected benign tumors with a high risk of degeneration into malignant ones.
• Monitoring the progress of treatment and after its completion in order to predict relapse.
• After removal of the pathological neoplasm.
• To predict the risk of metastasis of harmful pathologies.

It is also necessary for pregnant women to find out what the AFP tumor marker shows. In this case, the typical situation is when its level is high. This is due to the fact that the embryo is perceived by the body as a foreign body, and it tries to defend itself. But if Alpha protein is reduced, pathologies in the fetus should be suspected, for example, Down syndrome, trisomy and many others. At the same time, exceeding an already high level of protein also indicates problems with the development of the fetus, including the risk of intrauterine death.

4.Risks and what can affect the result?

Risks of AFP analysis

If you are donating blood for an alpha-fetoprotein test, then possible risks may only be associated with taking blood from a vein. In particular, the appearance of bruises at the site of blood sampling and inflammation of the vein (phlebitis). Warm compresses several times a day will relieve phlebitis. If you are taking blood thinning medications, you may bleed at the puncture site.

What can affect the results of an AFP analysis?

Alpha-fetoprotein levels may become abnormal if:

• A woman carries more than one child;
• The woman has gestational diabetes;
• The patient smokes. Smoking increases AFP levels.

What is AFP and for what reasons does its rate change?

It is known that the AFP tumor marker is a protein substance that is produced by embryonic cells in the body of a developing fetus, liver cells in adults and tumor cells if a tumor is formed.
Consult an Israeli specialist
Unlike others, this substance is always present in the body in certain quantities. Its decrease or increase in the body of an adult in relation to the norm is a signal of a possible neoplasm in the body, which can be either benign or malignant. If AFP protein decreases in a pregnant woman, fetal pathologies are likely to occur.

An increase or decrease in the level of this substance is not an unambiguous diagnosis, but is a vector for further action.

Taking into account the characteristics, tumor markers are divided into two types - specific and non-specific. In the first case, an increase in its quantity indicates the development of pathology, that is, it is produced by a tumor. In the second, the protein is synthesized by healthy liver cells to protect the body, and in the event of the development of a malignant process, their number sharply increases in order to attack harmful formations.

Thus, it can be concluded that AF-protein has anti-cancer effects.

Requirements for preparing the patient before taking the test

Testing for AFP tumor marker is what is called cancer prevention through early detection and initiation of treatment, and will be effective if properly prepared.

There are no special requirements for the patient, but these recommendations must be followed:

It is believed that the best time for the procedure is the morning period from 8 to 12 hours.

Women should consult their doctor about the best day for testing based on their menstrual cycle.

When to check the AFP tumor marker level in pregnant women and during lactation, the doctor determines, choosing the optimal period and giving individual recommendations for preparation.

What is comprehensive screening?

To get a complete picture of your baby's health, your doctor will look at the results of the first trimester screening, which included an assessment of NUT (nuchal translucency thickness), and the results of the second trimester screening, which included an AFP test.

This is sometimes called comprehensive screening.

By evaluating the results of prenatal ultrasounds and blood tests, your doctor can try to determine whether your baby is at risk for developing abnormalities. These may include a neural tube defect such as spina bifida or chromosomal disorders such as Down syndrome (trisomy 21) and Edwards syndrome (trisomy 18).

When is alpha-fetoprotein tested?

Alpha protein testing is usually done in the second trimester between 16 and 18 weeks.

Typically, a biochemical blood test as part of screening includes three more indicators in addition to AFP: the hCG hormone, inhibin A, and free estriol. This analysis is also called the quadruple test.