Alpha fetoprotein

and Martina Feichter, medical editor and biologist

Dr. med. Andrea Reiter is a freelance writer for the medical editorial team.

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Martina Feichter studied biology with an elective subject pharmacy in Innsbruck and also immersed herself in the world of medicinal plants. From there it was not far to other medical topics that still captivate her to this day. She trained as a journalist at the Axel Springer Academy in Hamburg and has been working for since 2007 - first as an editor and since 2012 as a freelance writer.

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Alpha-fetoprotein (more precisely: alpha-1-fetoprotein, α1-fetoprotein, AFP) is a protein that is only produced in very small quantities by the liver and intestinal cells. However, certain tumors, especially metastases of the liver, can increasingly form AFP. Read everything you need to know about the laboratory value AFP and when it is determined.

What is Alpha Fetoprotein?

Alpha-fetoprotein (AFP) is a protein that is produced in very small quantities by liver and intestinal cells and, moreover, by the embryonic yolk sac during pregnancy. AFP has a transport function for proteins in the blood of the unborn child.

Normally, AFP is therefore only detectable in the blood of children and adults in very small concentrations. However, there are tumors, such as liver metastases, that can produce a great deal of AFP. The protein is therefore also called “AFP tumor marker”.

When is the alpha-fetoprotein determined?

If a tumor in the liver is suspected, the AFP concentration in the blood is determined. AFP is also measured regularly in patients with liver cirrhosis, as they have an increased risk of liver cancer. The tumor marker is also measured to monitor the progress of a treated liver tumor. Because if it rose again, the cancer could have returned.

During pregnancy, the AFP value is measured if there is a suspicion of child malformations or developmental disorders. The concentration of AFP can then be determined in the maternal blood or in the amniotic fluid.

Alpha-fetoprotein - normal values

In healthy adults, the AFP value in the blood serum is below 20 nanograms per milliliter (ng / ml).

age	Female	masculine
up to 4 weeks	<18694.0 ng / ml	<16387.0 ng / ml
1 to 12 months	<77.0 ng / ml	<28.3 ng / ml
1 to 2 years	<11.1 ng / ml	<7.9 ng / ml
3 to 11 years	<5.6 ng / ml
12 to 17 years	<4.2 ng / ml
from 18 years	<13.4 ng / ml

The following blood values ​​for alpha-fetoprotein are usually measured during pregnancy:

Week of pregnancy (SSW)	AFP mean values
15th week of pregnancy	20.4 ng / ml
17th week of pregnancy	30.0 ng / ml
19th week of pregnancy	35.5 ng / ml
20th week of pregnancy	46.0 ng / ml
22nd week of pregnancy	58.0 ng / ml
23rd week of pregnancy	68.0 ng / ml
25th week of pregnancy	125.0 ng / ml
30th week of pregnancy	200.0 ng / ml
35 weeks	200.0 ng / ml
40th week of pregnancy	140.0 ng / ml

When is the alpha-fetoprotein low?

Too low AFP values ​​in the blood of pregnant women can indicate trisomy 21 (Down syndrome) in the unborn child. However, the value alone does not allow a diagnosis and is also subject to a technical spread. Therefore, more and more examinations must always follow in order to be able to reliably determine a possible developmental disorder of the unborn child.

When is the alpha fetoprotein increased?

Elevated AFP values ​​can be measured in the following cases:

• Liver cancer
• Liver metastases
• Inflammation of the liver caused by a virus (viral hepatitis)
• Cirrhosis of the liver
• toxic liver disease
• Testicular tumor
• Ovarian tumor
• Gastrointestinal tumor (AFP is increased in 20 percent of cases)
• Lung cancer (AFP is increased in 20 percent of cases)

If the alpha-fetoprotein is increased during pregnancy, this can indicate possible undesirable developments in the unborn child - such as spina bifida ("open back"). Even with a multiple pregnancy, the AFP level in the blood of the expectant mother can be higher than normal.

What to do if the alpha-fetoprotein is elevated

In the case of non-pregnant women, if there is an increased concentration of AFP in the blood, it must always be clarified whether the cause could be a tumor.

Further examinations are also carried out in pregnant women if the alpha-fetoprotein blood value is outside the normal range. Only the synopsis of all examination results allows a statement to be made about the state of health of the unborn child.

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