Alpha-fetoprotein (AFP; synonym: α-1-fetoprotein) is an oncofetal protein (protein) that is physiologically produced in the liver, gastrointestinal tract, and yolk sac (which performs metabolic functions until the liver is formed and is the source of hematopoietic stem cells). AFP is an important parameter in prenatal diagnostics to exclude malformations of the unborn child. In addition, AFP is also important as a tumor marker. Tumor markers are substances produced naturally in the body by tumors and are detectable in the blood. They can provide an indication of a malignant (malignant) neoplasm and serve as a follow-up test in cancer aftercare.
The procedure
Material needed
- Blood serum
Preparation of the patient
- Not necessary
Disruptive factors
- In patients receiving therapy with high doses of biotin (> 5 mg/day), blood sampling should be performed at least 8 hours after the last application.
Normal value (AFP as tumor marker)
| Normal value | <7.00 ng/ml |
| Gray area | 7.1 -20 ng/ml |
Normal value (AFP in serum, in pregnancy: 14th-21st SSW)
| Normal value | 0.5-2.0 MoM* |
| Marginal | 2.0-2.5 MoM |
| Suspicion of neural tube defect | > 2.5 MoM |
* MoM” (multiple of the median) means a multiple of the median. So the average value referred to here is the median, not the mean. The MoM value relates the measured value to an average value. It thus describes how much higher or lower a measured value is in relation to an ideal value.
Indications
- Suspected hepatocellular carcinoma (liver cancer).
- Suspected bronchial carcinoma (lung cancer).
- Suspected gastrointestinal tumors (tumors of the gastrointestinal tract).
- Suspected germ cell tumors – tumors originating from the testes (testicles) or ovaries (ovaries).
- AFP screening in pregnancy (neural tube defects).
Interpretation
Interpretation of increased values
- Hepatocellular carcinoma (liver cancer; detectable in 85% of cases – levels above 1,000 ng/ml are almost always a definite indication of hepatocellular carcinoma) [1st choice tumor marker].
- Bronchial carcinoma (lung cancer; detectable in 20% of cases).
- Gastrointestinal tumors
- Germ cell tumors (testicular – detectable in 70% of cases with non-seminoma/testicular cancer (testicular carcinoma); ovarian; outside gonads).
- Liver diseases such as hepatitis (liver inflammation) or cirrhosis – connective tissue remodeling of the liver with accompanying functional impairment.
- Pregnancy
- Anencephaly (88%)
- Spina bifida (79%)
- Multiple pregnancy (20%)
- Incorrectly dated pregnancy (30%)
- Infants
Interpretation of lowered values
- Low AFP levels are considered to be indicative of trisomy 21 (Down syndrome) in the unborn child between the 14th and 20th week of gestation.
