Alpha-fetoprotein (AFP) is a protein measured during a blood test. It is primarily produced during fetal life. Its concentration then drops sharply after birth. Results outside the reference range can raise questions. Understanding what this marker is, its role, and the reasons for its variations is essential for better communication with your doctor. This article provides factual insight to help you interpret your results.

What is Alpha-fetoprotein (AFP)?

Alpha-fetoprotein is a protein belonging to the glycoprotein family. The fetus’s liver synthesizes it in large quantities during pregnancy. In adults, liver cells continue to produce it, but at a much lower level.

Role and Function of this Protein

During embryonic development, this protein plays a major role. It acts particularly in regulating the osmotic pressure of fetal blood. Furthermore, it transports various essential molecules, such as hormones or fatty acids, to the growing tissues of the fetus.

Utility of Blood Testing

AFP testing is a valuable tool in several medical contexts. In an adult or child, an elevated level can be an indicator of certain pathologies, particularly liver or tumor-related conditions. During pregnancy, its analysis in maternal blood is used for screening certain fetal developmental abnormalities.

Why Monitor Alpha-fetoprotein Levels?

Alpha-fetoprotein levels indicate general health as they are linked to several body systems. Its variations can indeed reflect liver activity, the presence of certain tumor processes, or the proper course of fetal development. This illustrates the interconnectedness of biological systems.

A Marker Used for Decades

AFP was first identified in 1956. Its utility as a tumor marker, particularly for primary liver cancer, was established in the 1970s. Since then, research has refined its predictive value in monitoring chronic liver diseases.

Importance of Screening and Follow-up

A persistent abnormality in AFP levels should not be ignored. For example, an uninvestigated elevation could delay the diagnosis of a liver pathology. Early detection, especially in the context of liver disease monitoring, is important for management.

Interpretation in Context

It should be noted that approximately 2 to 3% of the adult population may present a slight elevation of AFP without an associated serious pathology. This increase is often related to non-tumor liver diseases, such as hepatitis or cirrhosis. The interpretation of results must therefore always be done in a global clinical context.

How to Interpret Your Test Results?

A laboratory results sheet presents precise information. Here’s how to read it.

Example of result:

• ALPHA-FETOPROTEIN (AFP)
• Result: 7.2 ng/mL
• Reference values: < 10 ng/mL

Understanding Units and Codes

The abbreviation “ng/mL” means nanograms per milliliter. This is the most common unit of measurement for AFP. Some laboratories may use other units, such as kU/L (kilo-units per liter).

Laboratories often use color codes. Red indicates a result outside the norm, while green or the absence of color indicates a normal value. Symbols like arrows (↑ or ↓) or an asterisk (*) can also draw attention.

What are Reference Values?

Each laboratory establishes its own reference values. They depend on the local population and the analysis method. Typically, these intervals represent the values found in 95% of a large sample of healthy people.

Checklist for Reading Your Analysis

To quickly analyze your AFP results, follow these steps:

• Verify that the name on the document is yours.
• Locate the line corresponding to AFP, your result, and its unit.
• Identify the indicated reference range.
• Compare your value to this range.
• Note the presence of any color codes or symbols.
• Read any comments from the biologist.
• Check the date of collection.

What are the Pathologies Linked to Alpha-fetoprotein?

An abnormal AFP level can be associated with different clinical situations, whether it’s a high level or, in the context of pregnancy, a low level.

Pathologies Associated with High AFP Levels

Hepatocellular Carcinoma

This primary liver cancer is the most known cause of marked AFP elevation, observed in 60 to 70% of cases. The proliferation of cancer cells reactivates the production of this protein, which is normally low in adults. Symptoms may include weight loss, abdominal pain, or a palpable mass. Diagnosis relies on imaging (ultrasound, CT scan, MRI) and sometimes a biopsy.

Germ Cell Tumors

Certain testicular or ovarian tumors, originating from embryonic cells, can produce large quantities of AFP. Symptoms include a testicular mass or pelvic pain. The assessment combines imaging, the measurement of other markers (such as β-hCG), and tumor analysis.

Chronic Hepatitis and Cirrhosis

Chronic inflammation and regeneration of liver cells, as in cases of viral hepatitis or cirrhosis, can cause a moderate elevation of AFP. This increase is generally less than 100 ng/mL. Monitoring these diseases includes a complete liver panel and regular imaging examinations.

Pathologies Associated with Low AFP Levels During Pregnancy

Trisomy 21 (Down Syndrome)

During the second trimester of pregnancy, an abnormally low alpha-fetoprotein (AFP) level in maternal blood indicates an increased risk of trisomy 21 for the fetus. Medical professionals incorporate this marker into a global risk calculation with other markers and ultrasound data. If the medical team deems the risk high, they may propose additional tests such as circulating fetal DNA testing or amniocentesis.

Situations Associated with High AFP Levels During Pregnancy

Neural Tube Defects

Conversely to trisomy 21, a high AFP level in maternal serum can indicate a risk of neural tube defect in the fetus (e.g., spina bifida). In this case, more AFP passes into the maternal circulation. A detailed morphological ultrasound is then essential to confirm or rule out the anomaly.

Advice and Medical Follow-up

The course of action depends on the AFP level and the clinical context.

Follow-up Schedule According to AFP Level

• Slightly Elevated AFP (10-20 ng/mL): A simple blood test in 1 to 3 months is often recommended. If the level remains stable, more spaced-out monitoring may be considered.
• Moderately Elevated AFP (20-200 ng/mL): A specialized consultation (hepatologist, oncologist) and liver imaging are generally necessary to search for a cause.
• Highly Elevated AFP (>200 ng/mL): A complete and urgent assessment is essential to establish a precise diagnosis and begin rapid management.
• During Pregnancy: Follow-up is defined by the obstetrician according to prenatal screening protocols and the results of other examinations.

Supportive Measures for Liver Health

No diet can directly normalize AFP levels. However, if the elevation is related to liver disease, adopting a good lifestyle is essential to support liver function.

• Limit or eliminate alcohol consumption.
• Adopt a balanced diet, rich in fruits, vegetables, and good quality fats (Mediterranean diet type).
• Maintain regular physical activity and a healthy weight.
• Avoid self-medication, as some medications can be toxic to the liver. Discuss any supplement intake with your doctor.

When to Consult a Specialist?

A prompt consultation is justified if:

• Your AFP level exceeds 100 ng/mL without a known cause.
• Your level progressively increases over several successive tests.
• You present unusual symptoms (fatigue, jaundice, abdominal pain).
• You are pregnant and prenatal screening reveals a significant anomaly.

Simple monitoring, prescribed by your general practitioner, may be sufficient if the elevation is minimal, stable, and an initial assessment has revealed nothing concerning.

Frequently Asked Questions About Alpha-fetoprotein

Is an Elevated AFP Always a Sign of Cancer?

No, absolutely not. Many benign situations can increase it, such as hepatitis, cirrhosis, or even liver regeneration after an injury. A high level is a signal that triggers investigations, but it is not a diagnosis in itself.

Can Certain Medications Influence AFP Levels?

No medication directly affects AFP production. However, treatments that affect the liver can indirectly cause drug-induced hepatitis and thus moderately raise AFP. Conversely, the effectiveness of a treatment for liver cancer is often followed by a decrease in AFP levels.

Why is AFP Sometimes Measured in Amniotic Fluid?

Measuring AFP in amniotic fluid, obtained by amniocentesis, is much more accurate than maternal blood testing for the diagnosis of certain fetal anomalies. It is offered in specific situations, after discussion with the medical team.

Can Alpha-fetoprotein Be Used to Monitor Treatment Effectiveness?

Yes. It is a very important tool for monitoring patients treated for hepatocellular carcinoma or germ cell tumors. A significant decrease in the level after treatment is a sign of a good response. Conversely, a re-increase may indicate a recurrence.

How Do AFP Levels Evolve During a Normal Pregnancy?

Values gradually increase, reach a peak around the 32nd week of pregnancy, and then decrease until delivery. After birth, the level rapidly drops in the mother and returns to normal within a few weeks.

Additional resources

• To deepen your knowledge of this blood marker, click here.
• To extend your knowledge and decipher other markers, more articles are available here.

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