Alpha FetoProtein (AFP) Test

Ayyan Web

Alpha-fetoprotein (AFP) is a protein produced in the liver of a developing fetus. During the development of a baby, some AFP passes through the placenta and reaches the mother’s blood. An AFP test measures the level of AFP in pregnant women during the second trimester of pregnancy.

Alpha Fetoprotein Test

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Also Known As: AFP, Total AFP, AFP-L3%, Alpha-fetoprotein (Total), Alpha-fetoprotein-L3 Percent, α1- Fetoprotein

This blood test is used to determine the levels of alpha-fetoprotein (also known as AFP or a-fetoprotein). AFP levels are often elevated above the values found in healthy individuals in cases of various malignant diseases, such as liver damage.

There is no correlation between AFP concentration and tumor size, tumor growth, stage, or degree of malignancy that has been demonstrated so far. Very high AFP values generally indicate serious liver problems. As AFP values increase during liver regeneration, moderately elevated values are found in alcohol-mediated cirrhosis of the liver and acute viral hepatitis, as well as in hepatitis B carriers.

Why to Get Tested:

When to get Tested:

all pregnant women should be offered an AFP test sometime between the 15th and 20th week of pregnancy. The test may be especially recommended if you:

  • Have a family history of birth defects
  • Are 35 years or older
  • Have diabetes

Sample Required

  1. Pregnant mother serum is needed. It is stable for 24 hours at 2 to 8 °C.
  2. Take 3 to 5 ml of blood in the disposable syringe.
    1. Keep the syringe for 15 to 30 minutes and then centrifuge for 2 to 4 minutes. In this way can get a clear serum.

Precaution for sample

  • Keep serum at 2 to 8 °C if the test is performed within 24 hours, otherwise, freeze it at -20 °C.

Normal Values

Source 1

Maternal serum level AFP
14 weeks of gestation 25.6 ng/mL (median)
16 weeks of gestation 34.8 ng/mL (median)
18 weeks of gestation 47.3 ng/mL (median)
20 weeks of gestation 64.3 ng/mL (median)
21 weeks of gestation74.9 ng/mL (median)
Fetal serum level AFP
First-trimester peak200 to 400 mg/dL
later on, fall 1% of the peak
Cord blood<5 mg/dL
Adult AFP
97% of the healthy population<8.5 ng/dL
100% of the healthy population<15.0 ng/dL

Source 2

  • Adult = <40 ng/mL (<40 mcg/L)
  • Child (<1 year) = <30 ng/mL

Increased AFP Level Seen In:

  1. Maternal serum level >2 times the median level will be seen in:
    1. Multiple gestations.
    2. Fetal death.
    3. Malformations e.g. anencephaly.
  2. Increased AFP concentration in maternal serum and amniotic fluid is seen in:
    1. open neural tube defects like anencephaly, spina bifida, omphalocele, esophageal or duodenal atresia.
    2. Threatened abortion.
    3. Fetal distress.
    4. Intrauterine death of the fetus.
    5. Fetal congenital abnormalities.
    6. Abdominal wall defects like gastroschisis.

Other Conditions Are:

  1. Renal abnormalities
  2. Cystic hygroma.
  3. Hydrops fetalis.
  4. Turner syndrome.
  5. Bowel obstruction.
  6. Twins.
  7. Feto-maternal hemorrhage.
  8. Sacrococcygeal Teratoma.

Decreased Maternal Serum AFP Is Seen In:

  1. Down syndrome (Trisomy 21).
  2. Molar pregnancy.
  3. Spontaneous abortion.
  4. overestimated gestational age.

Low Level Of AFP With An Abnormal Value Of HCG And Estriol (Triple Screening) Is Indicative Of :

  1. Trisomy 21 (Down’s syndrome).
  2. Trisomy 18 (Edwards syndrome)
  3. Or other chromosomal abnormalities.

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