The AFP tumor marker in the blood is examined for the following reasons:
- Diagnosis of primary hepatocellular carcinoma (liver cancer);
- high risk of developing a liver tumor (with cirrhosis, chronic hepatitis);
- suspected oncological disease (confirmation of the diagnosis of teratoblastoma of the testis, low-grade tumors);
- predicting the likelihood of liver cancer metastasis;
- determination of antitumor therapy;
- screening for the quality of removal of malignant tissues after radical surgery;
- prediction of the clinical picture of the disease, its progression, the likelihood of relapse or remission;
- diagnosis of diseases of the lungs, liver, uterus, mammary glands, etc .;
- monitoring the condition and development of the fetus in the second trimester of pregnancy.
The obstetrician-gynecologist, oncologist and other narrow specialists are referred to the study and interpreted the results as necessary.
|Pregnancy week||Indicator (U / ml)|
The amount of AFP is determined by adding special reagents to the serum isolated from venous blood. Due to the fact that different laboratories can use different chemicals and equipment, each research center relies on its own averaged indicators, so the norm may vary slightly.
An analysis of alpha-fetoprotein is recommended for all pregnant women with gestational age up to 12 weeks. Repeated analyzes are prescribed if the first were with abnormalities. Strict indications for the analysis are some conditions in pregnant women:
- the child is conceived from blood relatives;
- the birth of a previous child with a malformation or hereditary pathology;
- the first birth of a woman after the age of 35;
- the negative impact on the body of a pregnant woman of various physical factors (poisons, radiation, etc.);
- the presence in the past of infertility in a couple, miscarriages (spontaneous), stillbirths;
- taking shortly before pregnancy or in the early stages of gestation of drugs with toxic effects on the fetus;
- the presence of a hereditary pathology or genetic mutation in future mothers and fathers;
- X-ray examination of a woman in early pregnancy.
Information A woman’s blood is taken from a vein. To determine the result, 10 ml is needed. After the material for analysis is taken, it is sent to laboratory assistants to determine the concentration of AFP.
Before you come to blood sampling points for alpha-fetoprotein analysis, you should follow a few simple conditions so that the results are as accurate and informative as possible:
- 10-14 days before the test, you must refuse to take any medications, because they, accumulating in the blood and internal organs of a woman, can cause distorted results of the analysis for fetal protein;
- 1 day before the test, fatty, fried, salty, spicy foods and alcoholic beverages should be excluded from the diet;
- 1-2 days before the analysis on AFP it is necessary to limit as much as possible any physical activities (including carrying weights, general cleaning of the house, etc.);
- the last meal before the analysis should be in the evening, no later than 21.00;
- in the morning, on the day of analysis, it is allowed to use only purified water, not more than 100-200 ml, so as not to reduce the true concentration of protein in the mother’s blood;
- AFP analysis should be taken in the morning, a few hours after waking up, so the laboratory should be as close as possible to the woman’s place of residence.
What is alpha fetoprotein?
The physiological parameters of AFP detected in the blood range from 10 ng / ml to 8 IU / ml.
IU / ml * 1,21 = ng / ml;
ng / ml * 0,83 = IU / ml.
To standardize the indicator and analyze deviations, the value of MoM (multiples of median – English), or the multiplicity factor of the median was introduced – the average value of the marker value, characteristic for a certain period of normal (ascending).
MoM allows you to compare the values of the analysis made during pregnancy at different periods, as well as use data from various laboratories.
Normally, the AFP level is in the range of 0,5 – 2,5 MoM.
The data obtained may vary depending on the biochemical methods used.
There are two ways to determine:
For research is used:
- the liquid part of the blood is plasma or serum;
- fluid located between the pleura (pleural);
- ascitic (taken from the abdominal cavity);
- cystic contents;
- fluid located in the uterine cavity (amniotic).
What is AFP and what is its role in pregnancy?
AFP indicators increased with:
- malignant tumors of the liver, gall bladder and ducts;
- neoplasms from pancreatic tissue;
- cancer of the stomach, large intestine;
- malignant processes in the tissues of the broncho-pulmonary system;
- with cancer of the genital glands of men and women (testicles and ovaries);
- tumor metastases to other organs.
The increase in AFP is provided by non-oncological processes:
- cirrhotic changes in the liver;
- acute, latent (latent) and chronic infectious hepatitis;
- chronic stage II alcoholism, in which liver functions are severely impaired;
- with chronic diseases of the hepatic-biliary system, leading to the development of chronic liver failure syndrome.
An important criterion for developing diseases is an increase in AFP in obstetric and gynecological practice.
AFP level increased with:
- multiple pregnancy;
- necrotic processes of the liver tissue in a developing child (under the influence of viral diseases);
- embryonic malformations leading to the formation of anencephaly (absence of the cerebral hemispheres, soft tissues of the head and bones), defects (crevices) of the spine, the appearance of umbilical hernias, renal failure of the child, defective muscle formation and aponeurosis of the abdominal wall of the developing fetus;
- other variants of pathological developmental disorders.
In some diseases, a decrease in the content of alpha-fetoprotein is also possible. Pathological processes in a pregnant woman lead to this condition. A decrease in AFP background may occur when:
- the development of Down syndrome in a child;
- malformations accompanied by developmental delay;
- fetal death of the fetus;
- beginning abortion;
- “False” pregnancy;
- cystic drift (vesicular growth of chorionic villi);
Please note: during pregnancy, AFP is determined as an additional method when performing prenatal screening, certainly against the background of basic diagnostic procedures.
Lotin Alexander, medical observer
At different stages of pregnancy, the concentration of alpha-fetoprotein in a woman’s body will be different. Measurement is performed in international units per 1 ml of patient’s blood (IU / ml).
|Pregnancy, weeks||The minimum concentration of AFP, IU / ml||The maximum concentration of AFP, IU / ml|
|1 – 13||0,5||15|
|14 – 16||15||60|
|17 – 20||15||95|
|21 – 24||27||125|
|25 – 28||52||140|
|29 – 30||67||150|
|31 – 32||100||250|
|33 – 42||The analysis is not carried out due to lack of information|
In the early stages, AFP will be detected in minimal quantities, because the embryo is still small and practically does not secrete this protein. The maximum concentration is found to be normal at 32 weeks, when the processes of tissue development in the baby are completed and only growth, an increase in size begins.
More often with pregnancy pathology, you can find an increase in AFP in the mother’s blood. This can indicate many violations, so a woman doctor should warn in advance that additional research methods may be necessary – ultrasound, determination of the level of hCG (human chorionic gonadotropin) in the blood, amniocentesis (amniotic fluid test), etc.
An insufficient concentration of AFP in the mother’s blood is slightly less than excessive and also indicates a number of pathologies in the fetus.
Analysis of AFP during pregnancy: norms and deviations
If with small deviations from the norm you can not worry, since they are most often caused by errors in determining the number of obstetric weeks of pregnancy or by the specifics of the study in a particular laboratory, then significant differences can indicate serious pathologies. Under the close attention of doctors, women with reduced alpha-fetoprotein and increased hCG are included – they are at risk for Down syndrome in the fetus.
High AFP during pregnancy is more common than low. An anomaly occurs for a number of reasons:
- multiple births;
- large fruit;
- underdevelopment of various systems and organs of the child;
- transmission of viral infection from mother to fetus;
- umbilical hernia;
- non-growth of the abdominal wall in the baby;
- chromosomal pathology;
- high degree obesity in a pregnant woman;
- cystic drift;
- hydrocephalus in the fetus;
- risk of miscarriage.
If the protein level is elevated, this does not necessarily mean a serious pathology for the development of the child. In 20% of patients, AFP rises at 15–16 weeks due to Rhesus conflict, toxicosis, or fetal hypoxia. To clarify the diagnosis, you will need to re-do a study on the content of alpha-fetoprotein, conduct an ultrasound, analysis for hCG and amniocentesis.
A decrease in the content of alpha-fetoprotein is quite rare and is provoked by the following factors:
- threat of miscarriage in 1 trimester;
- cystic drift;
- abnormalities in the development of the embryo;
- gene pathologies;
- frozen pregnancy.
The main function of alpha protein is protective. It is he who prevents the aggressive effect of the immunity of the pregnant woman on the developing body of the child. A marker protein is involved in preventing the immune rejection reaction. Also, AFP performs a transport function in the fetus, performing oxygen transfer.
The primary source of isolation of this marker is the corpus luteum, located in the tissues of the ovary. After 5 weeks of an existing pregnancy, the baby’s emerging body begins to self-release AFP
The content of alpha-fetoprotein increases simultaneously both in the blood of the fetus and in the blood of his mother. Diagnostically valuable is the 12-16 week gestational age. The highest AFP value is characteristic for 32-34 weeks of pregnancy, then a slow decrease in value occurs.
After the birth of a child and the achievement of one year of life, the AFP indicator reaches the figures of an adult. A variety of techniques define different standards, which must be taken into account when decoding the values.
AFP in pregnant women
A blood test to determine the level of AFP for pregnant women can be prescribed along with an analysis for hCG. It will give the most accurate results at 16-18 weeks, but diagnostics can be prescribed earlier or later than this date.
Triple biochemical screening, including tests for alpha-fetoprotein, hCG and estriol, is performed to exclude fetal abnormalities: chromosomal abnormalities, organ defects, etc. The examination is not prescribed for all pregnant women, but if desired, a woman can undergo it on her own initiative. AFP analysis is required in such cases:
- blood relationship of parents;
- mother’s age is more than 35 years;
- miscarriages, stillbirths, history of infertility treatment;
- taking a woman toxic drugs to the fetus;
- the presence of genetic pathologies in parents;
- exposure to the body of a pregnant woman poisons, chemicals, etc .;
- radiography at the beginning of pregnancy;
- the presence in the family of a child with developmental defects.
|Gestational age:||Values, ME / ml||Values, ng / ml|
|up to 12 weeks||less 15||less 18,07|
|from 13 to 15 weeks||15 – 60||18,07 – 72,29|
|from 15 to 19 weeks||15 – 95||18,07 – 114,46|
|from 20 to 24 weeks||27 – 125||32,53 – 150,6|
|from 25 to 27 weeks||52 – 140||62,65 – 168,67|
|from 28 to 30 weeks||67 – 150||80,72 – 180,72|
|from 31 to 32 weeks||100 – 250||120,48 – 301,2|
Important! Interpretation of results is always carried out comprehensively. It is not possible to make an accurate diagnosis based on just one analysis.
Alpha-fetoprotein reaches its maximum concentration by 34 weeks, after which its level begins to decline.
An increased level of AFP is more than 2-3 times observed in the following diseases:
- anencephaly (gross pathology of the formation of cranial bones and cerebral hemispheres);
- malformation of the spine (spina bifida);
- malformations of the kidneys and liver in the embryo;
- atresia of the esophagus or intestines;
- umbilical hernia, gastroschisis (defect of the anterior abdominal wall),
- teratocarcinoma (cancer) of the yolk sac;
- pathology of the placenta;
- encephalocele (craniocerebral hernia);
- risk of miscarriage or premature delivery;
- large fruit;
- multiple pregnancy, etc.
Important: for the diagnosis of fetal development pathology, it is necessary to know the exact gestational age. The AFP level alone cannot serve as a diagnostic criterion.
Interpretation of results
Important! Standards vary depending on the reagents and equipment used in each particular laboratory. Therefore, when interpreting the results, it is necessary to use the standards adopted in the laboratory where the analysis was submitted. It is also necessary to pay attention to units of measure.
|Girls and non-pregnant women||Boys and Men|
|age:||IU / ml||ng / ml||age:||IU / ml||ng / ml|
|up to 4,3 weeks||no more 15740||no more 18963,86||up to 4,3 weeks||no more 13600||16385,54|
|from 4 weeks to a year||no more 64,3||no more 77,47||from 4 weeks to a year||no more 23,5||28,31|
|from a year and older||no more 7,29||no more 8,78||from a year and older||no more 7,29||8,78|
|Age||Values, ME / ml||ng / ml|
|Less than 1 month||0,5 – 13600 IU / ml||0,6 – 16385,54|
|1 – 12 months||0,5 – 23,5 IU / ml||0,6 – 28,31|
|More than 1 year||0,9 – 6,67 IU / ml||1 – 8,04|
|Female||Less than 1 month||0,5 – 15740 IU / ml||0,6 – 18963,86|
|1 – 12 months||0,5 – 64.3 IU / ml||0,6 – 77,47|
|More than 1 year||0,9 – 6,67 IU / ml||1 – 8,04|
How to convert ng / ml to IU / ml and vice versa for AFP:
Factors of influence on the result
- In patients of the Negroid race, an increased content of alpha-fetoprotein is noted, and in representatives of the Mongoloid race, on the contrary, it is reduced.
- Against the background of some endocrine pathologies, false-positive results of an AFP analysis can be determined.
- Reception of monoclonal antibodies
- Insulin-dependent diabetes reduces AFP in the blood of a pregnant woman
What pathological conditions are accompanied by an increase in AFP?
Elevated levels of alpha-fetoprotein in non-pregnant women, children and men may indicate the following malignant processes:
- hepatocellular carcinoma, hepatoblastoma (malignant neoplasms of the liver);
- hepatic metastases;
- oncology of the pancreas, colon or sigmoid colon, lungs, uterus and appendages, breast, gall bladder and bile ducts, as well as squamous cell carcinoma of the esophagus;
- germinogenic pathological formations in testicles or ovaries;
- embryonic tumors (teratomas);
- acute or chronic liver pathologies (hepatitis, alcohol intoxication, insufficiency, cirrhosis, jaundice);
- liver trauma, surgery;
- kidney stone disease;
- blockage of the bile duct;
- tyrosinemia (congenital inability to break down the tyrosine amino acid);
- ataxia-telangiectasia (Louis-Bar syndrome) – non-inflammatory enlargement of small vessels and cerebellar ataxia.
Important! Malignant processes are indicated by the excess of the AFP norm by several tens of times. In primary cancer, a substance concentration of more than 10 IU is observed in 95% of patients, and in half of the cases, the oncomarker emission is recorded already a quarter before the first symptoms of the disease.
A decrease in AFP level in dynamics often indicates effective chemotherapy for carcinomas2.
Low levels of AFP in patients with type 2 diabetes mellitus are associated with an increased risk of hepatocellular carcinoma3.
Too low an indicator indicates the following deviations:
- malnutrition (malnutrition);
- hypoxia (oxygen starvation);
- Down syndrome;
- Edwards syndrome (trisomy on the 18th chromosome),
- Patau syndrome (trisomy on the 13th chromosome),
- missed abortion;
- intrauterine death;
- diabetes or gestational diabetes in a pregnant woman;
- obesity of various types;
- low placenta previa;
- endocrine disorders.
Oncomarkers are specific elements that appear in human biological fluids against the background of the development of benign and malignant processes. Among them there may be hormones and enzymes, but the most common proteins are, for example, alpha-fetoprotein (AFP).
AFP is produced by the cells of the fetal egg in the body of a pregnant woman, but can also be detected in a child or man. It indicates the likelihood of developing a malignant process and allows you to diagnose cancer at an early stage. Also, a blood test for AFP helps to evaluate the effectiveness of antitumor treatment, reveals early metastases and indicates the condition of the fetus during pregnancy. etc.
At the moment, medicine knows two hundred tumor markers. One of them, AFP, is a protein macromolecule to which a component of carbohydrate or fat is attached. AFP is produced by malignant cells, after which it enters the bloodstream, where its level can be determined using enzyme-linked immunosorbent assay ELISA.
A regular AFP test of the blood of a pregnant woman allows you to control some of the immune reactions of the mother’s body. Since alpha-fetoprotein is produced by the embryo during pregnancy, the immunity of the expectant mother often identifies the fetus with a foreign agent and tries to attack it. That is why increased AFP in pregnant women should be considered the norm, and its low values, on the contrary, may indicate fetal malformations.
The AFP tumor marker is also determined in the body of adults and children, since it begins to be produced in the liver before birth (during embryonic development) and throughout life. Therefore, this indicator is one of the main criteria in the diagnosis of oncological pathologies of the liver and organs of the gastrointestinal tract.
The half-life of AFP is about 5 days. Therefore, the study of the tumor marker for several weeks after chemotherapy, radiation therapy or surgical procedures allows you to control the effectiveness of the treatment. If the level of alpha-fetoprotein continues to increase, then the prognosis for the patient is poor. If the intensity of AFP decrease is low, then the patient’s body may have left tumor particles or the process of metastasis has begun.
Serum is the biomaterial for AFP. But periodically, other biological media can be used: the secret of the pleural cavity of the lungs, bile, urine, ascitic or amniotic fluid.
Preparation for analysis
Research biomaterial: blood serum.
Fence method: venipuncture of the ulnar vein.
Recommended collection time: morning hours from 7.00 to 10.00.
Mandatory conditions: strictly on an empty stomach.
Other requirements for preparation for analysis are standard: