From the Guidelines
Normal Alpha-Fetoprotein (AFP) levels in adults are typically less than 10 nanograms per milliliter (ng/mL) or 10 micrograms per liter (μg/L).
Key Points to Consider
- During pregnancy, AFP levels naturally rise, with normal ranges varying by gestational age: at 16 weeks, levels are typically 10-30 ng/mL; at 17-18 weeks, 10-40 ng/mL; and at 19-20 weeks, 10-80 ng/mL 1.
- In newborns, AFP levels are naturally high (up to 100,000 ng/mL) but gradually decrease to adult levels by age one.
- Elevated AFP levels outside these ranges may indicate liver disease, certain cancers (particularly hepatocellular carcinoma and germ cell tumors), or neural tube defects in developing fetuses.
- AFP is produced primarily by the fetal liver and yolk sac during development, and its persistence at high levels in adults often signals abnormal cell growth or liver dysfunction.
- Some individuals have serum AFP levels that are chronically mildly elevated in the range of 15-30 ng/mL, which can be considered a false-positive result 1.
- Regular monitoring of AFP levels is important for high-risk patients, such as those with cirrhosis, hepatitis B or C, or a history of relevant cancers.
Important Considerations for AFP Levels
- Benign liver disease, such as hepatitis, can elevate serum AFP levels 1.
- Certain other benign liver disorders, such as hepatic toxicity from chemotherapy, can also elevate serum AFP levels 1.
- Tumor lysis can cause a rise in serum tumor marker levels, including AFP, during the first week of chemotherapy 1.
- Hepatocellular carcinoma and other cancers can produce AFP, so elevated serum AFP is not diagnostic for germ cell tumor in patients with poorly differentiated cancers 1.
From the Research
Normal Limits for Alpha-Fetoprotein (AFP) Levels
The normal limits for Alpha-Fetoprotein (AFP) levels vary depending on the individual's age, sex, and gestational age in pregnant women.
- In normal adults, the mean AFP level is approximately 3.04 ng/ml +/- 1.9 SD, with higher levels found in men compared to women 2.
- AFP levels decline rapidly after birth, reaching undetectable levels (less than 10 ng/ml) within several months after birth 2.
- In pregnant women, the normal range of maternal serum AFP levels between 15 and 20 weeks gestation is not explicitly stated, but it is recommended that laboratories establish their own normal range for this period 3.
- Reference ranges for AFP in early pregnancy have been calculated, with the 10th and 90th percentiles determined as reference levels 4.
- In cases of premature delivery before 33 weeks' gestation and postmature delivery after 40 weeks' gestation, maternal AFP levels may be elevated 5.
- High serum AFP levels (>7 ng/ml) have been found in approximately 1.7% of primary infertile men, and are associated with older age, lower sperm concentration, and more comorbidities 6.