AlphaFeto Protein (AFP) Pregnancy

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An alpha-fetoprotein (AFP) blood test checks the level of AFP in a pregnant woman's blood. AFP is a substance made in the liver of an unborn baby (fetus). The amount of AFP in the blood of a pregnant woman can help see whether the baby may have such problems as spina bifida and anencephaly. An AFP test can also be done as part of a screening test to find other chromosomal problems, such as Down syndrome (trisomy 21) or Edwards syndrome (trisomy 18). An AFP test can help find an omphalocele, a congenital problem in which some of the baby's intestines stick out through the belly wall.  
Normally, low levels of AFP can be found in the blood of a pregnant woman. No AFP (or only a very low level) is generally found in the blood of healthy men or healthy, nonpregnant women.  
The level of AFP in the blood is used in a maternal serum triple or quadruple screening test. Generally done between 15 and 20 weeks, these tests check the levels of three or four substances in a pregnant woman's blood. The triple screen checks alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), and a type of estrogen (unconjugated estriol, or uE3). The quad screen checks these substances and the level of the hormone inhibin A. The levels of these substances—along with a woman's age and other factors—help the doctor estimate the chance that the baby may have certain problems or birth defects.  
Screening tests are used to see what the chance is that your baby has a certain birth defect. If a screening test is positive, it means that your baby is more likely to have that birth defect and your doctor may want you to have a diagnostic test to make sure.  
Men, nonpregnant women, and children  
AFP is used to help detect and diagnose cancers of the liver, testes, and ovaries. It is often ordered to monitor people with chronic liver disorders such as cirrhosis or chronic hepatitis B because they have an increased lifetime risk of developing liver cancer. A doctor may order an AFP test, along with imaging studies, to try to detect liver cancer when it is in its earliest, and most treatable, stages.
If a patient has been diagnosed with hepatocellular carcinoma or another form of AFP-producing cancer, an AFP test may be ordered periodically to help monitor a patient's response to therapy and to monitor for cancer recurrence.
A relatively new test, called AFP-L3%, is sometimes also ordered to compare the amount of total AFP to the amount of one of the AFP variants called AFP-L3. The AFP-L3% test is not yet widely used in the U.S. but has gained wider acceptance in other countries such as Japan. The test is used to help evaluate the risk of developing hepatocellular carcinoma, especially in those with chronic liver disorder. An increase in the percentage of L3 to total AFP indicates an increased risk of rapidly developing this disorder and also of having less chance of survival.

A physician may order an AFP blood test when s/he:
·Check the developing baby (fetus) of a pregnant woman for brain or spinal problems (called neural tube defects). Such defects occur in about 2 out of every 1,000 pregnancies.1 The chance of a neural tube defect in a baby is not related to the mother's age. Most women whose babies have neural tube defects have no family history of these problems.  
·Check the developing baby (fetus) of a pregnant woman for Down syndrome.  
·Find certain cancers, especially cancer of the testicles, ovaries, or liver. But up to half of the people with liver cancer do not have high AFP levels.  
·suspects that someone has liver cancer or certain cancers of the testes or ovaries. Cancer may be suspected when, for example, lumps are felt in the abdominal area during a physical exam or when imaging tests detect possible tumors.  
·is monitoring a patient with chronic liver disorder for the emergence of hepatocellular carcinoma or another type of liver cancer.  
·is monitoring the effectiveness of treatment in a patient who has been diagnosed with and treated for a cancer of the liver, testes, or ovaries.  
·is monitoring for cancer recurrence.  
An AFP-L3% is sometimes ordered to help evaluate the risk of hepatocellular carcinoma when a patient has chronic liver disorder. This new test, however, is not widely used and its ultimate clinical utility has yet to be established.

Test results
An alpha-fetoprotein (AFP) blood test checks the level of AFP in a pregnant woman's blood. AFP is a substance made in the liver of a developing baby (fetus). The amount of AFP in the blood of a pregnant woman can help find certain problems with her baby.  
Normal AFP values may vary from lab to lab. Also, normal values vary with the age of the baby. A high or low AFP may mean that the age of the baby has been recorded wrong or not calculated correctly. An ultrasound may be done to check the baby's age more accurately.  
Men and nonpregnant women:
0–40 nanograms per milliliter (ng/mL) or micrograms per liter (mcg/L)

Women 15–18 weeks pregnant:
10-150 ng/mL or mcg/L


In pregnant women, the amount of AFP gradually rises starting in the 14th week of pregnancy. It continues to rise until a month or two before giving birth, then it slowly decreases. Values are generally slightly higher for black women than they are for white women. Values are slightly lower for Asian women than they are for white women. An accurate estimate of the age of the baby is needed to understand the AFP value correctly.  
The normal range of AFP values is adjusted for each woman's age, weight, and race; whether she has diabetes that needs injections of insulin; and the age of her baby (gestational age). If the age of the baby is changed after an ultrasound, the AFP must then be adjusted as well. Each woman and her doctor need to look at the range of AFP values that is normal for her when she has an AFP test.  
High values  
In a pregnant woman, high alpha-fetoprotein values can mean:  
·The age (gestational age) of the baby is wrong.  
·The woman is pregnant with more than one baby, such as twins or triplets.  
·The baby has a neural tube defect.  
·The baby's intestines or other abdominal organs are outside the body (called an abdominal wall defect or omphalocele). Surgery after birth will be needed to correct the problem.  
·The baby is not alive.  
In a nonpregnant adult, high alpha-fetoprotein values can mean:  
·Cancer of the liver, testicles, or ovaries is present.  
·Liver disorder, such as cirrhosis or hepatitis, is present.  
·Alcohol abuse is present.  
Low values  
In a pregnant woman, a low level of alpha-fetoprotein can mean:  
·The age (gestational age) of the baby is wrong.  
·The baby has Down syndrome.  
In a nonpregnant adult, alpha-fetoprotein is not normally present.  

Increased AFP levels may indicate the presence of cancer, most commonly liver cancer, cancer of the ovary, and germ cell tumor of the testes. However, not every liver, ovary, or testes cancer will produce significant quantities of AFP. Elevated levels may be sometimes seen with other cancers such as stomach, colon, lung, breast, and lymphoma, although it is rarely ordered to evaluate these conditions. Other disorders such as cirrhosis and hepatitis can also cause increased levels.
When AFP is used as a monitoring tool, decreasing levels indicate a response to treatment. If concentrations after cancer treatment do not significantly decrease, usually to normal or near normal levels, then some of the tumor tissue may still be present. If concentrations begin to increase, then it is likely that the cancer is recurring. If AFP levels are not elevated prior to treatment, then the test will not generally be useful to monitor the effectiveness of treatment or to monitor for recurrence.
When the AFP concentrations of people with chronic liver disorder go from moderately elevated to greatly elevated, their risk of developing liver cancer increases. When total AFP and AFP-L3% are significantly elevated, then the affected person has an increased risk of having or developing hepatocellular carcinoma in the next year or two. However, both AFP and AFP-L3% concentrations can be elevated, and fluctuate, in people with chronic hepatitis and cirrhosis. In these cases, a sharp increase in AFP is more important than the actual numerical value of the test result.

Also you should know
The test result is very dependent on accurate determination of the gestational age of the fetus. If the gestational age of the fetus has not been accurately determined, the results may be either falsely high or low.
In multiple gestation pregnancies, calculation of the risk of Down syndrome or Edwards syndrome is difficult. For twin pregnancies, a "pseudorisk" can be calculated comparing results to normal results in other twin pregnancies. For higher gestation pregnancies, risk cannot be calculated from these tests.
Evaluation of the risk of open neural tube defects in twin pregnancies can be determined, although it is not as effective as in singleton pregnancies.
If you have had a First Trimester Screen, then a triple/quad screen (second trimester screening) is not performed because the risks for Down syndrome and Edwards syndrome have already been assessed. However, if you and your doctor wish to use the results of both first and second trimester screening to assess the risk of chromosome abnormalities, then integrated or sequential screening may be employed. For more on these, see the article on First Trimester Screening.

Things that may affect the results of your test include:  
·If there is more than one baby (fetus). This increases the level of AFP in the blood.  
·If you have gestational diabetes.  
·If you smoke. This increases the level of AFP in the blood.  
·If you had a medical test that used radioactive tracers in the past 2 weeks.  

Down syndrome (DS) is a chromosomal abnormality, also called trisomy 21, that affects about 1 in 800 live births. People with DS have an extra copy of part or all of chromosome 21. Most affected children have some retardation of growth and development. The risk of carrying a fetus with Down syndrome increases with the mother's age, especially in women over 40 years old. For more information, visit the National Down Syndrome Society.

Neural tube defects are serious birth defects: the brain, spinal cord, or their coverings do not develop completely. There are three kinds of neural tube defects:
·Anencephaly: incomplete development of the brain and the skull  
·Encephalocele: a hole in the skull through which brain tissue protrudes  
·Spina bifida: the most common neural tube defect, in which the spine does not close properly during early pregnancy (For more information on spina bifida, visit the Spina Bifida Association of America.)  
To help prevent formation of a neural tube defect the U.S. Public Health Service recommends that all women of childbearing age should take 0.4 mg of folic acid daily.

Edwards syndrome (trisomy 18) is a condition in which there are 3 copies of chromosome 18. The risk of carrying a fetus with Edwards syndrome also increases with maternal age. Edwards syndrome is associated with multiple abnormalities and is usually fatal, with live-born infants rarely living beyond one year of age. The frequency of this abnormality is much less than Down syndrome, occurring in only 1 in 3000 live births. For more information, see the Trisomy 18 Foundation web site.



 
 
 
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All information on this page is intended for your general knowledge only and does not provide medical advice, diagnosis or treatment.