What is the normal value of alpha-fetoprotein (AFP)?

The human body consists of numerous types of cells, and many substances circulating in the body can serve as indicators of cancer development. For example, alpha-fetoprotein (AFP) is a biomarker that can reflect the presence of hepatocellular carcinoma (HCC). In healthy individuals, AFP is typically undetectable or present only at very low levels; however, its concentration may rise significantly in cases of liver cancer. So, what constitutes the normal reference range for AFP? The following section addresses this question.

What Is the Normal Reference Range for Alpha-Fetoprotein (AFP)?

Generally, the normal reference range for AFP is <25 μg/L (equivalent to <25 ng/mL). As AFP serves as a tumor marker for multiple malignancies—most notably primary hepatocellular carcinoma—it is a glycoprotein primarily synthesized by fetal hepatocytes. During active hepatitis or hepatic cell regeneration, AFP levels may increase to varying degrees. Under physiological conditions, AFP concentrations rise during pregnancy. In contrast, elevated serum AFP levels in adults are associated with primary hepatocellular carcinoma (60–70% of cases), testicular cancer, ovarian tumors, malignant teratomas, pancreatic cancer, gastric cancer, and other malignancies. Therefore, AFP results must be interpreted in conjunction with other liver function tests, as well as imaging studies such as abdominal ultrasound and CT scans.

Additional Information: Causes of Elevated Alpha-Fetoprotein (AFP)

1. Hepatocellular Carcinoma (HCC)

AFP levels often begin rising approximately eight months before clinical symptoms of HCC appear. Individuals with cirrhosis, chronic hepatitis, or a family history of liver cancer should undergo regular AFP screening based on their individual risk profile. Epidemiological data indicate that approximately 80% of adult HCC patients exhibit elevated serum AFP levels.

2. Pregnancy

AFP levels typically rise markedly beginning around the third month of gestation, peaking and stabilizing between the seventh and eighth months of pregnancy. Additionally, mild-to-moderate AFP elevation (usually 50–300 μg/L) may occur during active chronic hepatitis; however, unlike in HCC, such elevations tend to be modest and transient rather than persistently progressive.

3. Fetal Neural Tube Defects

AFP measurement in amniotic fluid or maternal plasma is used for prenatal screening. In cases of neural tube defects—including spina bifida and anencephaly—AFP leaks from the exposed neural tissue into the amniotic fluid, resulting in abnormally elevated amniotic AFP concentrations.

The above provides an overview of the normal reference range for alpha-fetoprotein (AFP). We hope this information is helpful to you.