Alpha fetoprotein

Fetal alpha globulin; AFP

Blood test

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Definition

Alpha fetoprotein (AFP) is a protein produced by the liver and yolk sac of a developing baby during pregnancy. AFP levels go down soon after birth. It is likely that AFP has no normal function in adults.

A test can be done to measure the amount of AFP in your blood.

How the Test is Performed

A blood sample is needed. Most of the time, blood is typically drawn from a vein located on the inside of the elbow or the back of the hand.

How to Prepare for the Test

You do not need to take any special steps to prepare.

How the Test will Feel

You may feel slight pain or a sting when the needle is inserted. You may also feel some throbbing at the site after the blood is drawn.

Why the Test is Performed

Your health care provider may order this test to:

  • Screen for problems in the baby during pregnancy. (The test is done as part of a larger set of blood tests called quadruple screen.)
  • Diagnose certain liver disorders.
  • Screen for and monitor some cancers.

Normal Results

The normal values in males or nonpregnant females are 0.7 to 9.3 ng/mL (0.7 to 9.3 µg/L).

The examples above are common measurements for results of these tests. Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your provider about the meaning of your specific test results.

What Abnormal Results Mean

Greater than normal levels of AFP may be due to:

References

Dugoff L, Wapner RJ. Prenatal diagnosis of congenital disorders. In: Lockwood CJ, Copel JA, Dugoff L et al, eds. Creasy and Resnik's Maternal-Fetal Medicine: Principles and Practice. 9th ed. Philadelphia, PA: Elsevier; 2023:chap 30.

Lee P, Jain S, Pincus MR, et al. Diagnosis and management of cancer using serologic and other body fluid markers. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 76.

Russo ML, Mahoney R, Driscoll DA, Al-Kouatly H. Genetic screening and diagnosis. In: Landon MB, Galan HL, Jauniaux ERM, et al, eds. Gabbe's Obstetrics: Normal and Problem Pregnancies. 9th ed. Philadelphia, PA: Elsevier; 2025:chap 12.

GO

Review Date: 8/18/2025

Reviewed By: LaQuita Martinez, MD, Department of Obstetrics and Gynecology, Emory Johns Creek Hospital, Alpharetta, GA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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