Alpha-fetoprotein (AFP) in children, adults and the pregnancy

Synonyms: Alpha-fetoprotein, AFP, alpha-Fetoprotein, AFP.

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Scientific editor: M. Merkusheva, PSPbGMU them. Acad. Pavlov, general medicine.
October, 2018.

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Overview

Tumor markers - specific elements that appear in human biological fluids on a background of benign and malignant processes. Among them may be hormones and enzymes, but the most common proteins, such as alpha-fetoprotein (AFP).

AFP is produced by cells of the ovum in the body of a pregnant woman, but can also be detected in a child or a man. He points to the likelihood of developing a malignant process and allows you to diagnose cancer at an early stage. Also blood test AFP contributes to assessing the effectiveness of cancer treatment, detect early metastasis and indicates the status of the fetus during pregnancy. t. d.

At the moment, two hundred medicine known tumor markers. One of them, AFP, the macromolecule is a protein to which is attached a component carbohydrate or fat. AFP produced by malignant cells, and then enters the bloodstream, where its level may be determined by the ELISA immunoenzymatic assay.

Regular research AFP pregnant woman's blood allows you to control some immune responses of the maternal organism. Since alpha-fetoprotein during pregnancy is made by the embryo, the immunity expectant mother often equates a fetus with a foreign agent and tries to attack him. That is why an increased AFP in pregnant women should be considered as the norm, and its low values, on the contrary, may be indicative of fetal malformations.

AFP tumor marker is also defined in the body of adults and children, as in the liver begins to produce before birth (during the period of embryonic development) and throughout life. The measure is one of the main criteria in the diagnosis of liver cancer and pathologies of the gastrointestinal tract. AFP significance lies in the fact that he has an independent anti-tumor activity - may bind and remove the malignant cells of the liver, uterus, respiratory tract, mammary gland, and so on. d.

The half-life of AFP is about 5 days. Therefore, tumor marker research for several weeks after chemotherapy, radiation therapy or surgical procedures allows you to monitor the effectiveness of treatment. If the level of the AFP continues to increase, the unfavorable prognosis for the patient. If the intensity of AFP reducing low, then the body of the patient may remain particles or tumor metastasis process began.

Biomaterial for AFP is a serum. But occasionally may be used and other biological media: secret lung pleural cavity, bile, urine, ascitic or amniotic fluid.

testimony

AFP tumor marker in the blood is investigated for the following reasons:

• Diagnosis of primary hepatocellular carcinoma (liver cancer);
• high risk of liver cancer (hepatic cirrhosis, chronic hepatitis);
• suspicion of cancer (testicular teratoblastomy confirmation of diagnosis, low-grade tumors);
• predicting the probability of cancer metastasis to the liver;
• definition of anticancer therapy;
• screening for removal of malignant tissue quality after radical surgery;
• prediction of the clinical picture of the disease, its progression, the likelihood of relapse or remission;
• diagnosis of lung diseases, liver, uterus, mammary glands and t. d .;
• monitoring and development of the fetus in the second trimester of pregnancy.

To research and interpret the results of an obstetrician-gynecologist, oncologist, and other narrow specialists as needed.

interpretation of results

Important! Norms vary depending on the reagents and equipment used in a particular laboratory. Therefore, when interpreting the results it is necessary to use standards adopted precisely in the lab where to be tested. It is also necessary to pay attention to the units.

These Invitro Laboratory¹:

Girls and nonpregnant women	Boys and men
age:	IU / ml	ng / ml	age:	IU / ml	ng / ml
to 4.3 weeks	not more than 15740	no more 18963.86	to 4.3 weeks	not more than 13600	16385,54
from 4 weeks to a year	not more than 64.3	not more than 77.47	from 4 weeks to a year	not more than 23.5	28,31
on-year and older	not more than 7.29	not more than 8.78	on-year and older	not more than 7.29	8,78

Helix laboratory data¹:

Floor	Age	Values ​​IU / ml	ng / ml
Male	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

Important! Interpretation of the results is always carried out comprehensively. An accurate diagnosis on the basis of only one analysis impossible.

How to transfer ng / ml IU / ml, and vice versa for AFP:

• IU / ml = 0.83 * ng / ml
• ng / ml = IU / ml / 0.83

Factors affecting the result

• Patients blacks marked the high content of alpha-fetoprotein and the representatives of the Mongolian, on the contrary, decreased.
• Against the background of some endocrine abnormalities may be determined by analysis of false positive results in the AFP.
• Receiving Monoclonal Antibodies
• Insulin-dependent diabetes reduces the AFP in the blood of pregnant

Increasing values

Elevated levels of alpha-fetoprotein in non-pregnant women, children and men can point to the following malignancies:

• hepatocellular carcinoma, hepatoblastoma (malignant neoplasms of the liver);
• liver metastases;
• oncology pancreas, colon or sigmoid colon, lung, uterus and appendages, breast, gallbladder and bile channels, as well as squamous cell cancer of the esophagus;
• germinogennye pathological formations in the testes or ovaries;
• embryonal tumors (teratomas);
• acute or chronic liver disease (hepatitis, alcohol intoxication, failure, cirrhosis, jaundice);
• liver injury, surgery;
• nephrolithiasis;
• biliary tract blockage;
• tyrosinemia (congenital inability to cleave the amino acid tyrosine);
• ataxia-telangiectasia (Louis-Bar syndrome) - noninflammatory increase in small vessels and cerebellar ataxia.

Important! About malignant processes indicates excess AFP norm in a few dozen times. In primary cancer substance concentration of more than 10 IU observed in 95% of patients, and in half of the cases already fixed ejection tumor marker for the quarter before the first symptoms.

low AFP

Reducing the level of AFP in the dynamics are often indicative of effective chemotherapy carcinomas².

Low levels of AFP in patients with type 2 diabetes mellitus is associated with increased risk of developing hepatocellular carcinoma³.

AFP in pregnant women

Typically, the tumor marker AFP in pregnancy is rarely determined individually. Most often, research is being conducted as part of the triple screening, along with free estriol and hCG. In pregnant women, this method makes it possible to diagnose cancer pathology of the uterus and appendages, breast and liver evils of child development. Also it allows you to predict the development of preeclampsia: Extremely high level of AFP in the blood of women in the 2nd trimester of pregnancy is a risk factor for preeclampsia⁴. Beginning in the 10 th week of an expectant mother is gradually increased AFP levels. By week, its norm is:

Gestational age:	Values ​​IU / ml	Values ​​ng / ml
up to 12 weeks	less than 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 the results is always carried out comprehensively. An accurate diagnosis on the basis of only one analysis impossible.

Maximum concentration of alpha-fetoprotein reaches to week 34, after which it starts to decrease levels.

Low AFP during pregnancy

Too low value of the indicator shows the following deviations:

• hypotrophy (insufficient supply);
• hypoxia (lack of oxygen);
• Down's syndrome;
• Edwards syndrome (trisomy of chromosome 18)
• Patau syndrome (trisomy of the 13th chromosome)
• missed abortion;
• intrauterine death;
• diabetes or gestational diabetes in pregnant women;
• obesity of various types;
• low placenta previa;
• endocrine disorders.

High AFP in pregnant women

Elevated levels of AFP in more than 2-3 times observed for the following diseases:

• anencephaly (gross pathology formation of the cranial bones and brain hemispheres);
• hydrocephalus;
• malformation of the spine (spina bifida);
• liver and kidney malformations in the embryo;
• atresia of the esophagus or intestine;
• omphalocele, gastroschisis (abdominal wall defect)
• teratocarcinoma (cancer) of the yolk sac;
• Pathology of the placenta;
• encephalocele (craniocerebral hernia);
• risk of miscarriage or premature delivery;
• large fruit;
• multiple pregnancy and so on. d.

Important: for the diagnosis of pathology of fetal development is necessary to know the exact date of pregnancy.
AFP level alone can not serve as a criterion for diagnosis.

Preparation for analysis

The biomaterial for the study: blood serum.

Method of sampling: the antecubital vein venipuncture.

Recommended time of collecting the material: the morning from 7.00 to 10.00.

Mandatory conditions: strict fasting.

Other requirements for preparation for standard analysis:

• yesterday at a dinner not to eat heavy, spicy, fatty, acidic and spicy foods;
• per day deleted reception alcohol, soft drinks (or Eleutherococcus tinctures ginseng, energy) drugs;
• Daily limit exercise and heavy lifting, to avoid emotional stress;
• 2-3 hours to stop smoking;
• a few hours to go to ordinary water, eliminate the use of tea, coffee, juices and so on. d.

Additionally:

• the blood does not pass after physiotherapy procedures: massage, electrophoresis, exercise, etc .;.
• the test is carried out before baseline surveys (ultrasound, MRI, X-ray, fluoroscopy), as well as other minimally invasive or instrumental diagnostic and treatment procedures.

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sources:

• 1. The reference ranges are made in laboratories Invitro and Helix.
• 2. L.A.Danilova, prof. blood, urine and other human biological fluids at different ages - SpetsLit, 2014.
• 3. Yang S. Lower alpha fetoprotein and higher risk of hepatocellular carcinoma, study from the type 2 diabetes mellitus patients. - Pubmed, 2018.
• 4. Long W. Second-trimester Maternal Serum Screening Biomarkers in the Risk Assessment for Preeclampsia. - Pubmed, 2018.