Human Chorionic Gonadotropin (HCG/hCG)

HCG/hCG/Human Chorionic Gonadotropin

HCG is a hormone that plays an important role in pregnancy, time at which its levels can vary widely. The hCG levels also vary between individuals. Outside a pregnancy, a high hCG level may be a sign of a health condition, such as cancer or liver disease, hence its importance for the clinical investigations.

HCG is a glycoprotein hormone that is normally found in the blood and urine only during pregnancy. It is secreted by the placenta. It is called "the pregnancy hormone", because of its unique role in supporting a pregnancy. During pregnancy, several hormones are involved in the proper functioning of the woman's body. HCG hormone supports the normal development of an egg in a woman's ovary, and stimulates the release of the egg during ovulation.

The early embryo tissue, which later forms part of the placenta, starts producing hCG. To maintain a pregnancy, hCG triggers the body to produce another hormone, progesterone. It can also help:

- promote the development of new blood vessels in the uterus;

- smooth the muscle cells in the middle layer of the uterine wall, which is important for maintaining pregnancy;

The hormone hCG is produced during pregnancy by cells formed in the placenta and nourishes the egg after it has been fertilized and attached to the wall of the uterus. In the first trimester of pregnancy, hCG ensures the maintenance of the corpus luteum and its secretion of estradiol and progesterone. HCG helps thicken the uterine lining to support a growing embryo and tells the body to stop menstruating. 

When does the body make hCG? 

All people have small amounts of hCG in their bodies (almost undetectable levels). The hCG levels rise fast (after conception) and continue to rise and then peak at around 10 weeks of pregnancy. After that, they gradually fall until childbirth. Once the placenta begins making hCG, it triggers the body to create more estrogen and progesteron. Together with hCG, these hormones help thicken the uterine lining and tell the body to stop menstruating (or release eggs). The correct balance of these three hormones sustains and supports the pregnancy.

A real "cocktail", made up of several chemical substances (hormones) is responsible for many less pleasant aspects of pregnancy, such as bloating, spotting, nausea and certain emotional states. Once the egg has met the sperm, the hormone hCG goes into action to amplify the production of estrogen and progesterone. At the same times, hCG suppresses the immune system, in order to support the development of the baby. 

People may be familiar with hCG because it is the hormone that pregnancy tests check for in the urine. A home test can first detect hCG levels that indicate pregnancy at about 1 to 2 weeks after conception. A doctor can also check for pregnancy by ordering a blood test to measure hCG levels. Testing the level of hCG in the blood can also help a doctor identify certain underlying health conditions, including some cancers, and check how effective cancer treatment is. HCG levels can first be detected by a blood test at about 11 days after conception and at about 12-14 days after conception by a urine test. Typically, the hCG levels will double every 72 hours. The level will reach its peak in the first 8-11 weeks, then decline and level off for the remainder of the pregnancy.

 

In rare cases, germ cell tumors or other cancers may cause the body to produce hCG. HCG can also be used as a treatment, to cause ovulation and to treat infertility in women. 

How is human chorionic gonadotropin produced?

After conception occurs, a fertilized egg travels through the fallopian tubes to the uterus. The fertilized egg (called an embryo) implants (attaches) into the wall of the uterus. This triggers the placenta to form. The placenta begins producing and releasing hCG into the blood and urine. HCG can be found in the pregnant's blood at around 11 days after conception. It takes slightly longer for hCG to appear on urine tests. 

HCG increases quickly (almost doubling every three days) for the first 8 to 10 weeks of pregnancy. Healthcare providers look at how quickly a person's hCG levels rise in early pregnancy to determine how the pregnancy and fetus are developing.

Clinical significance

Its rapid increase in serum levels immediately after conception makes HCG an excellent marker for early confirmation of pregnancy and monitoring its evolution.

Determination of serum HCG can be useful in anticipating the occurrence of spontaneous abortions, in diagnosing ectopic pregnancies or multiple pregnancies. 

The values of HCG increases in the first trimester of pregnancy and then gradually decreases towards the end of pregnancy. Significant, sudden decreases in HCG in a pregnant woman can be encountered in pregnancies that do not progress normally, in which case an immediate clinical examination is necessary. 

What level of hCG indicates pregnancy?

A urine hCG level as low as 6.3 to 12.5 U/l may be detectable by tests, indicating pregnancy. However, tests typically detect hCG levels closer to 20 to 50 U/l.

How quickly does hCG rise?

During pregnancy, hCG levels typically double every 24 hours during the first 2 months and peak at week 10.

What is a normal hCG level when not pregnant?

In people who are not pregnant, hCG levels are exceptionally low to undetectable. However, some experts approximate that hCG levels may increase in natal females with age, increases up to 14 U/l. Certain cancers may also cause increases in hCG levels.

HCG levels unrelated to pregnancy

Normal levels of hCG are typically undetectable in females who are not pregnant and in males.

Higher levels can sometimes point to an underlying health problem, such as:

- some cancers, including cancer of the liver, stomach, pancreas, lung, breast, or skin

- germ cell tumors of the ovary and testicles, which may be benign or malignant

- cirrhosis

- stomach ulcers

- inflammatory bowel disease

HCG as medication

Generic name: human chorionic gonadotropin (HCG) (injectable)
Drug class: Gonadotropins

Doctors sometimes prescribe hCG to combat the symptoms of conditions such as hypogonadism, in which the testes do not produce enough testosterone, sperm, or both.

What happens if missing a dose?

The doctor should be contacted if missing a dose of HCG.

What happens if overdosing?

Seeking emergency medical attention is what to do if thinking that too much of this medicine was used. An overdose of HCG is not expected to produce life-threatening symptoms, though.

What should I avoid?

The doctor's instructions should be followed about any restrictions on food, beverages, or activity while using HCG.

HCG side effects

Using HCG must be stopped and emergency medical help should be sought if having any of these signs of an allergic reaction: hives, difficulty breathing, swelling of the face/lips/tongue/throat.

The doctor must be called immediately if having any of these signs of a blood clot: pain, warmth, redness, numbness, or tingling in the arm or leg; confusion, extreme dizziness, or severe headache.

How is hCG used for fertility?

HCG injections can increase the chances of becoming pregnant when used with IVF (in-vitro fertilization) or IUI (intrauterine insemination). It works by inducing ovulation (when ovaries release an egg). If there is a history of infertility, monitoring hCG levels early in pregnancy can help the healthcare providers determine if a successful pregnancy has occurred.

Before using HCG as medication

This medication should not be used if the patient have ever had an allergic reaction to HCG, or if the patient has: 

- early puberty (also called precocious puberty); 

- a hormone-related cancer (such as prostate cancer);

- cancer or a tumour of the breast, ovary, or uterus;

- certain types of ovarian cysts;

- uncontrolled thyroid or adrenal dysfunction;

- a cancer or tumour of the hypothalamus or pituitary gland in the brain;

- vaginal bleeding without a known cause; or

- if the person is currently pregnant.

Before receiving HCG, the doctor must be called if the patient is allergic to this drugs or if the patient has: a thyroid or adrenal gland disorder, an ovarian cyst, unexplained vaginal bleeding, heart disease, kidney disease, epilepsy, migraines, or asthma.

If a patient is having any of these conditions, a dose adjustment may be needed and special tests, to safely use HCG.

Although HCG can help becoming pregnant, HCG should not be used if the patient is already pregnant. The patient should tell the doctor right away if becoming pregnant during treatment. The doctor should be told if the woman is breast-feeding a baby before using HCG.

Warnings

HCG is given as an injection under the skin or into a muscle. If using HCG at home, the doctor, nurse, or pharmacist will give the specific instructions on how and where to inject this medicine. One must not self-inject HCG if not fully understanding how to give the injection and properly dispose of used needles and syringes.

HCG can place the patient at higher risk for a blood clot. The doctor must be called if having any of these signs of a blood clot: pain, warmth, redness, numbness, or tingling in the arm or leg; confusion, extreme dizziness, or severe headache.

Some women using this medicine have developed a condition called ovarian hyperstimulation syndrome (OHSS), especially after the first treatment cycle. OHSS can be a life-threatening condition. The doctor must be called right away if having any symptoms of OHSS: severe pelvic pain, swelling of the hands or legs, stomach pain and swelling, shortness of breath, weight gain, diarrhea, nausea or vomiting, or if urinating less than normal.

HCG can cause early puberty in young boys. The doctor must be called if a boy using this medicine shows early signs of puberty, such as a deepened voice, pubic hair growth, and increased acne or sweating. 

Less serious side effects from HCG may include:

- headache;

- feeling restless or irritable;

- mild swelling or water weight gain;

- depression;

- feeling tired;

- breast tenderness or swelling; or

- pain, swelling, or irritation where the injection is given..

Using HCG can increase the woman's chances of having a multiple pregnancy (twins, triplets, quadruplets, etc). A multiple pregnancy is a high-risk pregnancy for the mother and for the babies. The doctor's instructions about any special care that may be needed should be followed during the pregnancy. 

How should HCG be used?

HCG must be used exactly as prescribed by the doctor. It must not be used in larger amounts or for longer than recommended. Directions on the prescription label should be followed.

Each disposable needle should only be used once. Used needles should be thrown away in a puncture-proof container (the pharmacist should be asked where getting one and how to dispose of the needles). This container should be kept out of the reach of children and pets.

To be sure HCG is helping the patient's condition, the doctor will need to check the subject on a regular basis. No scheduled appointments should be missed.

Some brands of HCG come in powder form with a separate liquid that one must mix together and draw into a syringe. Other brands are provided in single-dose prefilled syringes.

The medication should not be used if it has changed colours or if the liquid has any particles in it. In this case, the patient must call the doctor for a new prescription. Unmixed HCG should be stored at room temperature away from light, moisture, and heat. After mixing the HCG, it must be kept in the refrigerator until the patient is ready for the injection. Any mixed medicine that have not been used within 30 days after mixing should be thrown away.

What other drugs will affect HCG?

There may be other drugs that can interact with HCG. The doctor must be informed about all the prescription and over-the-counter medications that the patient uses. This includes vitamins, minerals, herbal products, and drugs prescribed by other doctors. It is not advisable to start using a new medication without telling it to the doctor.

How do pregnancy tests work?

Pregnancy tests (like urine tests, which can be done at home), are designed to detect changes in the level of the hCG hormone using a scientific technique. HCG can be detected in either blood or urine. However, a blood test is more accurate, because it can detect smaller amounts of hCG. 

HCG is a large molecule, made up of two separate components: alpha hCG and beta hCG. A pregnancy test comes with antibodies to detect the alpha hCG part and the beta hCG part. So, if a home pregnancy test shows that one is pregnant, it means that the hCG hormone in the urine is sandwiched by the antibodies on the strip that have been smeared on, so this component of the test triggers the release of a colored substance, creating that dark line that indicates a positive pregnancy test result.

Even though home pregnancy tests detect the hCG hormone in the urine, to determine whether or not one is pregnant, such tests cannot actually tell you how much hCG is present. It is important to go to the gynecologist to confirm the result with other tests. The fetus is usually visible on a transvaginal ultrasound when the hCG values are above 1500 units. When the beta hCG value is above 4000 units, the fetus is also visible on an abdominal ultrasound.

How hCG levels are tested?

An at-home pregnancy test will be positive if hCG is detected in the urine. A urine hCG test is performed by either urinating on a chemical strip or placing a drop of urine on a chemical strip. At-home urine tests typically require higher hCG levels to return a positive result.

It should be kept in mind that a low hCG level doesn't diagnose anything. It's just a tool to detect potential issues. If the healthcare provider is concerned about the hCG level, the levels should be tested again in two or three days. Then, the results will be compared, in order to get a better picture of what's going on with the pregnancy.

hCG testing

Level of the hCG hormone can first be detected through a blood test, at about 11 days after conception, and through a urine test (pregnancy test), at about 12-14 days after conception.

Normally, hCG levels will double at every 48-72 hours. Its levels will reach a "peak" in the first 8-11 weeks of pregnancy, and then the level will begin to decrease and at some point, human chorionic gonadotropin will remain at the same level for the rest of the pregnancy.

hCG Levels

While getting further along in pregnancy and the hCG level gets higher, the time it takes to double can increase to about every 96 hours.

A normal pregnancy may have low hCG levels and result in a perfectly healthy baby. The results from an ultrasound after 5 - 6 weeks gestation are much more accurate than using hCG numbers.

An hCG level of less than 5 mIU/mL is considered negative for pregnancy, and anything above 25 mIU/mL is considered positive for pregnancy.

An hCG level between 6 and 24 mIU/mL is considered a grey area, and it's likely needed to be retested to see if the levels rise to confirm a pregnancy.

The hCG hormone is measured in milli-international units per milliliter (mIU/mL).

A transvaginal ultrasound should be able to show at least a gestational sac once the hCG levels have reached between 1,000 - 2,000 mIU/mL. Because levels can differentiate so much and conception dating can be wrong, a diagnosis should not be made by ultrasound findings until the hCG level has reached at least 2,000 mIU/mL.

A single reading is not enough information for most diagnoses. When there is a question regarding the health of the pregnancy, multiple testings of hCG done a couple of days apart give a more accurate assessment of the situation.

The hCG levels should not be used to date a pregnancy since these numbers can vary so widely.

There are two common types of hCG tests. A qualitative test detects if hCG is present in the blood. A quantitative test (or beta) measures the amount of hCG actually present in the blood.

Types of hCG Tests

There are two common types of hCG tests; these are different types of blood tests to detect hCG:

- A qualitative test detects whether human chorionic gonadotropin is present in the blood; it doesn't specify the amount, just that there is hCG;

- A quantitative (or beta-hCG) test measures the amount of human chorionic gonadotropin that is actually present in the blood; the results are in milli-international units of hCG per milliliter of blood (mIU/mL).

 A positive test referring to beta-hCG test means that the woman is pregnant, and a negative test referring to beta-hCG test means that there is no pregnancy. 

Should hCG levels be checked regularly? How often is hCG level tested in pregnancy?

It's not common for doctors to routinely check the hCG levels unless the patient is showing signs of a potential problem. HCG levels are typically not checked more than once or twice during pregnancy. 

Healthcare providers check hCG levels in the first trimester, but usually don't need to check again. The hCG level may be rechecked if there is bleeding, experiencing severe cramping, or having a history of miscarriage.

If initial hCG levels are lower than the average, hCG levels are to be tested again in a few days. Assessing hCG levels is done sequentially, testing several days apart and comparing levels. 

Some prenatal genetic tests use hCG levels to check for the possibility of a fetus having a congenital disorder. 

Total serum HCG: too low or too high values

Low hCG levels in pregnancy 

During pregnancy, low levels of hCG are not always a cause of concern. This finding may only indicate that there could be a health issue to investigate.

Other times, low hCG can point to a more serious problem. 

Low hCG can also indicate that the fetus is not growing appropriately. 

What do too low hCG levels mean?

A low or declining hCG level can mean many things and should be rechecked within 48-72 hours to see how the level is changing. A low level may indicate:

- an incorrect calculation of the due date (miscalculation of pregnancy dating, of last menstrual period);

- possible miscarriage (losing of pregnancy);

- blighted ovum/pregnancy (pregnancy with no embrion); 

- an ectopic pregnancy (extrauterine pregnancy).

If the hCG is low for the gestational age of the pregnancy, the healthcare provider will recheck the pregnant's hCG levels in two or three days or perform an ultrasound to get a better look at the uterus.

High hCG levels in pregnancy

As with low levels, high levels of hCG do not necessarily indicate a problem with a pregnancy. Some people simply have higher levels. 

If a woman has high hCG levels, it could point to twins or triplets, though only a scan can confirm this.

What do too high hCG levels mean?

A high level of the hCG hormone can mean many things and should be rechecked within 48-72 hours to evaluate changes in the level. A high level can mean:

- miscalculation of the pregnancy dating (miscalculation of last menstrual period);

- molar pregnancy (the placenta and the fetus do not develop correctly);

- multiple pregnancy (several fetuses; twins, triplets or more);

- abnormal growths on the uterus.

What are normal hCG levels by week in pregnancy?

Note that the following values represent Beta hCG reference values. 

Human chorionic gonadotropin is produced only during pregnancy, almost exclusively in the placenta. Levels of the hCG hormone, which is detected in the mother's blood and urine, increase dramatically in the first trimester and can contribute to nausea and vomiting associated with pregnancy. Here are the beta hCG values, depending on the week of pregnancy (gestational age: by convention, pregnancies are measured in weeks, starting with the first day of the woman's last menstruation).

HCG levels in pregnancy

hCG levels can vary widely from one pregnant person to another. A test measures hCG in units per liter (U/l).

Typical levels of hCG throughout pregnancy are: 

Week since last menstrual period        Standard hCG range (U/l)

4                                                           0-750

5                                                          200-7,000

6                                                          200-32,000

7                                                          3,000-160,000

8-12                                                    32,000-210,000

13-16                                                  9,000-210,000

16-29                                                  1,400-53,000

29-41                                                  940-60,000

During the first 8 weeks of pregnancy, concentrations of hCG in the blood and urine usually double every 24 hours. 

Levels of the hormone typically peak at around 10 weeks, decline until 1 week, then remain constant.

The chart shows how the hCG levels rise quickly and steadily in the first trimester before declining:

Weeks since last menstrual period                                                     hCG levels (mIU/mL)

3                                                                                                         5-50

4                                                                                                         5-426

5                                                                                                         18-7,340

6                                                                                                         1,080-56,500

7 to 8                                                                                                  7,650-229,000

9 to 12                                                                                                25,700-288,000

13 to 16                                                                                              13,300-254,000

17 to 24                                                                                              4,060-165,400

24 to 40                                                                                              3,640-117,000

non-pregnant                                                                                      55-200ng/ml

* These numbers are just a guideline - every woman's level of hCG can rise differently. It is not necessarily the level that matters, but rather the change in the level.

These numbers should be used as a guide only. The levels may rise differently in every woman. It's not the numbers that matters as much as how the number changes between different weeks. The healthcare provider will let the pregnant patient know if the hCG levels need to be checked again and what the test results mean for the pregnancy. An important point to remember is that healthy pregnancies may have lower than average hCG levels.

Non-pregnant women have hCG levels between 0 and 5 mIU/ml.

What Can Be Expected After a Pregnancy Loss?

Most women can expect their levels to return to a non-pregnant range at about 4 - 6 weeks after a pregnancy loss has occurred.

This can be differentiated by how the loss occurred (spontaneous miscarriage, abortion, natural delivery) and how high the levels were at the time of the loss.

Healthcare providers usually will continue to test hCG levels after a pregnancy loss to ensure they return back to <5.0.

Gestational trophoblastic disease

One medical concern about higher levels of hCG is that they may indicate gestational trophoblastic disease (GTD).

GTD can occur during or after pregnancy. It causes abnormal cells to grow in the uterus. Some can be cancerous, though most are benign. Treatment depends on the mass of cells and whether it is cancerous or benign.

To remove the mass, the doctor may recommend dilation and curettage, which involves sucking away the mass with a surgical vacuum and gently scraping away any remaining abnormal cells. Or, a doctor may recommend a hysterectomy to remove the uterus.

Summary HCG

HCG plays a key role in pregnancy, during which levels rise significantly. Especially high or low levels during pregnancy can indicate a problem, but this is not always the case.

In other people than pregnant women, high levels of hCG sometimes indicate an underlying health condition, possibly one that affects fertility.

If a woman gets a positive test result, she is most likely pregnant. False positives are extremely rare. However, there are some conditions that may cause a false positive, such as certain types of cancer and early miscarriage. Some antibodies may also interfere with test results.

Medications that contain hCG may interfere with hCG levels, as well. These medications are often used in fertility treatments, and the health care provider should advise the patient on how a test may be affected.

All other medications such as antibiotics, pain relievers, contraception or other hormone medications should not have any effect on a test that measures hCG.

AFP - Alpha Fetoprotein

 Alpha-Fetoprotein Analysis

Introduction

Human α-fetoprotein (AFP) is a tumor-associated fetal mammalian glycoprotein involved in ontogenic and oncogenic growth. This tumor marker is encoded by the AFP gene on chromosome 4q25. The fetal protein is a 70-kDa single polypeptide chain containing 3% to 5% carbohydrate. This protein exhibits a triplicate domain structure configured by intramolecular loops dictated by disulfide bridging. AFP occupies an α-1 anodic position in the electrophoretic profile, running slightly slower compared to albumin. AFP is synthesized in the yolk sac, fetal liver, and gastrointestinal tract during pregnancy but is re-expressed in multiple adult tumors of mixed mesodermal or endodermal origin.

In the clinical laboratory, AFP has been employed both as a post-operational tumor marker and as a gestational age-dependent fetal defect marker, demonstrating utility in screening for neural tube defects and aneuploidies. When a fetus has neural tube defects, maternal serum AFP levels are elevated, whereas chromosomal disorders are associated with lower levels. Yolk sac and liver-derived AFP have different carbohydrate content. The half-life of AFP is 4 to 5 days. Similar to albumin, serum AFP binds and transports many ligands such as bilirubin, fatty acids, retinoids, steroids, heavy metals, dyes, flavonoids, phytoestrogens, dioxin, and various drugs. 

AFP can be fractionated by affinity electrophoresis into 3 glycoforms: L1, L2, and L3, based on the reactivity with the lectin lens culinaris agglutinin. AFP-L3 binds strongly to lens culinaris agglutinin through an additional α-1-6 fucose residue attached at the reducing terminus of N-acetylglucosamine, in contrast to the L1 isoform. The L1 isoform is typically associated with non-hepatocellular carcinoma inflammation of the liver disease. The L3 isoform is specific to malignant tumors, and the detected presence can identify patients who need increased monitoring for the development of hepatocellular carcinoma in high-risk populations such as chronic hepatitis B and C and liver cirrhosis.

Alpha-Fetoprotein (AFP) Test 

What is an Alpha-fetoprotein (AFP) Test?

What is an AFP (alpha-fetoprotein) tumor marker test?

An AFP tumor marker test is a blood test that measures the level of AFP (alpha-fetoprotein) in a sample of blood. AFP is a protein that a developing baby makes. Normally, some AFP passes from the baby into the pregnant person's blood. An AFP test is a test that is mainly used to measure the level of alpha-fetoprotein (AFP) in the blood of a pregnant person. The test checks the baby's risk for having certain genetic problems and birth defects. An AFP test is usually done between 15 and 20 weeks of pregnancy. In other patients than pregnant women, the test is usually used to help diagnose certain types of cancer and to check how well treatment is working. Certain conditions can make a baby's body release more or less AFP. 

During pregnancy, if the AFP blood levels are higher or lower than normal, it may be sign that:

- The baby has a high risk of having a genetic disorder, such as:

                - A neural tube defect, which is a serious condition that causes abnormal development of a developing baby's brain and/or spine;

              - Down syndrome, a genetic disorder that causes intellectual disabilities and other health problems.

- The estimated due date is wrong. AFP levels normally rise and fall at set times during pregnancy, so an abnormal AFP may mean that the baby is due earlier or later than estimated. This is the most common reason for abnormal AFP levels. 

- If pregnant with more than one baby. Each baby makes AFP, so the AFP blood levels will be higher with two or more babies.

AFP is a protein that the liver makes when its cells are growing and dividing to make new cells. AFP is normally high in unborn babies. After birth, AFP levels drop very low. Healthy children and adults who aren't pregnant have very little AFP in their blood. 

AFP in non-pregnant people is mainly measured as a tumor marker. Tumor markers are substances that are often made by cancer cells or by normal cells in response to cancer. High levels of AFP can be a sign of cancer of the liver, ovaries or testicles.

An AFP tumor marker test cannot be used by itself to screen for or diagnose cancer. That's because other conditions can increase AFP levels, including liver diseases that aren't cancer. And some people who do have liver, ovarian, or testicular cancer will have normal AFP levels. So, an AFP tumor marker test can't rule out cancer for sure. But when used with other tests and exams, AFP tumor marker testing can help diagnose and monitor cancers that cause high AFP levels. 

Other names: total AFP, AFP Maternal, Maternal Serum AFP, msAFP screen, alpha-fetoprotein-L3 Percent. 

What is AFP used for?

An AFP tumor marker test may be used during the diagnosis and/or treatment of cancer of the liver, ovaries, or testicles that make high levels of AFP. It is used to:

- Help confirm or rule out a cancer diagnosis when used with other exams and tests;

- Predict how cancer may behave over time;

- Monitor cancer treatment. AFP levels often go up if cancer is growing and go down when treatment is working;

- Check whether cancer has returned after treatment.

In certain cases, results from an AFP tumor marker test may be used to guide treatment choices for specific types of cancer. The test may also be used to monitor your health if you have chronic (long lasting) hepatitis or cirrhosis of the liver. These conditions aren't cancer, but they increase your risk of developing liver cancer.

Why do I need an AFP tumor maker test?

You may need an AFP tumor marker test if:

- A physical exam and/or other tests suggest that you may have cancer of the liver, ovaries, or testicles;

- You are currently being treated for a cancer that causes high AFP levels. Measuring your AFP test can show how well your treatment is working;

- You have completed treatment for a cancer that increased your AFP level. You may need an AFP tumor marker test from time to time to check whether your cancer is coming back.

If you have chronic hepatitis or cirrhosis, you have a higher risk of developing liver cancer. A very high level of AFP or a sudden increase can be an early sign of liver cancer. Most medical experts don't recommend measuring AFP levels to screen for cancer in these diseases. But, some health care providers may still use an AFP tumor marker test with other tests to watch for liver cancer.

If a woman is pregnant, AFP test is routinely offered between the 15th and 20th week of pregnancy. Your provider may especially recommend the test if you:

- Have a family history of birth defects;

- Are 35 years or older;

- Have diabetes;

- Have used medicines or drugs during pregnancy that could harm the baby.

What happens during an AFP tumor marker test?

A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.

Will I need to do anything to prepare for the test?

You don't need any special preparations for an AFP tumor marker test. 

Are there any risks to the test?

There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

What do the results mean?

The most common cause of abnormal AFP test results during pregnancy is an error estimating the due date. But a result that isn't normal may also be a sign of possible problems:

- Lower than normal AFP levels may mean that the baby has a genetic disorder that causes intellectual disabilities and health problems;

- Higher than normal AFP levels may mean that the baby has an increased risk of having a neural tube defect, such as:

    - Spina bifida, a condition in which the bones of the spine don't close around part of the spinal cord;

    - Anencephaly, a condition in which the brain does not develop properly.

High AFP levels may also mean only that there are more than one baby. A false-positive result may also be obtained. That means that the AFP results aren't normal, but the baby is healthy.

If the AFP test results aren't normal, it is likely that more tests are performed in order to help make a proper diagnosis.

Specimen collection

A blood sample is collected from the vein using aseptic techniques, and universal precautions are applied. Serum AFP levels are measured as part  of a maternal triple or quadruple screening test or for other diagnostic purposes in nonpregnant female or male patients. Urine samples collected in plain or universal bottles may also be assayed for AFP levels, although this may be significantly lower compared to serum levels.

Specimens derived from sera are stable at room temperature or 4°C for at least 1 week and can be stored for several months at -20°C. The type of centrifugation and non-stable refrigeration frost-free cycles can affect AFP levels. Thus, monitoring various steps involved in sample collecting, storage, and preparation processes is crucial in maternal serum AFP screening programs.

Amniocentesis is needed to assay AFP levels in the amniotic fluid. A diagnostic amniocentesis involves using an ultrasound-guided, hollow needle through the maternal anterior abdominal wall into the amniotic cavity to draw out amniotic fluid for AFP immunoassay. AFP may also be measured by elution from blood spots collected on filter paper. Serum AFP is somewhat thermostable, and samples may be shipped at ambient temperatures after separation from red blood cells.

Procedure for Amniocentesis (From 15 Weeks Gestation):

The subsequent steps outline the amniocentesis process:

- Confirm the patient's identity and gestational age of the pregnancy;

- Conduct pretest counseling, which typically includes genetic counseling;

- Obtain informed consent from the patient;

- Adhere to hand washing and universal precautions;

- Position the patient appropriately;

- Clean the exposed area of the abdomen;

- Use a local anesthetic if necessary;

- Carefully introduce the ultrasound-guided, hollow needle through the anterior abdominal wall into the amniotic cavity;

- Aspirate 15 to 20 mL of amniotic fluid;

- Send the sample for AFP assay.

Procedure for AFP Analysis:

The procedure for AFP analysis is as follows: 

- Competitive radioimmunoassay has been widely used to quantify AFP;

- Currently, AFP is mainly measured by non-isotopic immunoassays;

- These immunoassay systems employ enzyme, fluorescent, or chemiluminescent labels;

- There are 2 types of immunoassays for measuring AFP: (1) competitive and (2) two-site solid-phase immunometric assays;

- In a typical radioisotopic competitive type, purified iodine-125-labeled AFP is mixed with the sample containing AFP to compete for a limited amount of AFP antibody;

- The 2-site immunometric assays use a solid phase, such as magnetic particles, plastic beads, or microtiter plates;

- The solid phase is coated with anti-AFP antibodies and incubated with patient specimens or standards; 

- AFP in the sample reacts with the anti-AFP antibody and is immobilized in the solid phase;

- Unbound components of the specimen are removed by washing the solid phase;

- A second anti-AFP antibody labeled with an enzyme, radioactive, fluorescent, or chemiluminiscent label is incubated with the solid phase and reacts with AFP bound at a second epitope site;

- Polyclonal and monoclonal antibodies have been used in tandem for each step; 

- Washing the solid phase removes the unreacted label, and any additional reagent needed to generate a signal is added;

- The bound label can be measured directly in the case of a fluorescence or radioactive label;

- The solid phase must be incubated with substrate before the detection step for enzyme labels;

- A reagent must be added for chemiluminiscence labels to generate the chemiluminiscent signal;

- In all cases, the signal generated with the solid phase is directly proportional to the AFP concentration of the standard or unknown;

- AFP-L3% is measured using a microfluidics-based instrument that utilizes immunochemical and electrophoretic techniques.

Indications:

The following lists various situations or medical conditions in which an AFP assay is performed: 

- Advanced maternal age;

- Previous births with chromosomal or congenital disabilities, including neural tube defects;

- Family history of chromosomal or congenital disabilities, such as Down syndrome and spina bifida;

- Screening for certain types of cancers, such as liver cancer, testicular cancer, and ovarian cancer;

- To evaluate the progress of anti-cancer treatment.

Potential Diagnosis

Maternal Serum AFP Levels Elevated:

The following conditions are associated with elevated maternal serum AFP levels:

- Neural tube defects such as spina bifida and anencephaly

- Omphalocele

- Gastroschisis

- Sacrococcygeal teratoma

- Placental abnormalities

- Cystic hygroma

- Renal abnormalities such as polycystic kidney or absent kidney, urinary obstruction, and congenital nephrosis

- Osteogenesis imperfecta

- Threatened abortion

- Decreased maternal weight or intrauterine growth restriction

Maternal Serum AFP Low Levels:

The following factors may contribute to low levels of maternal serum AFP:

- Down syndrome

- Increased maternal weight

- Fetal demise

- Hydatidiform mole

- Trisomy 18, also known as Edwards syndrome

- Incorrect gestational age (older than calculated)

Non-Pregnant Female or Male AFP Levels Elevated:

The following conditions may lead to elevated AFP levels in non-pregnant females or males:

- Hepatocellular cancer

- Metastatic liver cancer

- Liver cirrhosis

- Hepatitis

- Germ cell tumors

- Yolk sac tumor

- Ataxia-telangiectasia

Normal and Critical Findings

Typical findings include:

- AFP levels in men and non-pregnant women vary by age and race but typically range from 0 to 40 ng/mL;

- Between 15 and 20 weeks of pregnancy, AFP levels typically range between 10 and 150 ng/mL;

- Adult blood levels greater than 200 ng/mL in patients with liver cirrhosis strongly indicate hepatocellular carcinoma.

Interfering Factors

The following factors have been implicated in false-positive AFP results:

- A period of 2 weeks after radiodiagnosis involving the use of radioactive tracers;

- Multiple gestations;

- Gestational diabetes;

- Cigarette smoking;

- Race (slightly higher levels in Black women and lower in women of Asian descent compared to Whites);

- Levels adjusted for weight;

- Amniotic fluid specimens contaminated with fetal blood may exhibit abnormally high AFP values, leading to misinterpretation of test results;

- Specimens from patients who have received preparations of mouse monoclonal antibodies may contain human anti-mouse antibodies, which may give falsely high results. Results must always be considered within the clinical context and previous results, especially when serial results monitor a patient's response to treatment.

Complications

Risks associated with phlebotomy include:

- Phlebitis

- Abnormal bruising and bleeding in patients with clotting disorders or those taking blood thinners.

Risks associated with amniocentesis include:

- Miscarriage

- Preterm delivery

Patient Safety and Education

Phlebotomy for blood AFP assay: patients need to be informed about the possible discomforts. This is a screening test. Depending on the outcome, more tests may be ordered to establish a diagnosis. A negative test does not necessarily indicate no risk, as a very low maternal blood AFP is associated with an increased incidence of Down syndrome. Hence, a low maternal blood AFP should be investigated.

Patients undergoing amniocentesis must be counseled about the procedure and the associated risks. The risk of obstetric mishap following amniocentesis exists; a miscarriage can happen in less than 1% of cases. Some rare complications of amniocentesis include preterm labor, infection (amnionitis), iatrogenic trauma, or injury to the developing fetus or mother. Following amniocentesis, patients may experience some cramp-like discomfort in the first few hours. Patients should report back to the hospital in case of vaginal bleeding, vaginal discharge, or increasing abdominal cramps.

Clinical Significance

Maternal blood AFP levels often comprise triple, such as AFP, unconjugated estriol, and human chorionic gonadotropin, or quadruple, such as AFP, estriol, human chorionic gonadotropin, and inhibin A, screening tests for congenital disabilities. Levels are typically interpreted for age, race, weight, and gestational age. As the levels of these markers change with gestational age, the results are expressed as multiples-of-median. The elevated levels imply a significant risk of having congenital disabilities; hence, further evaluation may be required to assess the level of risks. A substantial number of patients with elevated maternal AFP do not develop congenital disabilities, but an increased risk of obstretic complications such as premature membrane rupture, placenta accreta, and increta may exist. 

Low maternal AFP levels may suggest a risk for Down syndrome. In non-pregnant women and men, elevated levels are observed in cancers, especially liver cancer. Levels greater than 200 ng/mL in patients with cirrhosis suggest hepatocellular carcinoma. Elevated AFP levels can also be found in testicular and ovarian carcinoma. AFP is also useful for determining prognosis and monitoring therapy for hepatocellular carcinoma. The concentration of AFP is a prognostic indicator of survival. Elevated AFP concentrations (>10μg/L) and serum bilirubin concentrations greater than 2 mg/dL are associated with a decreased survival time.

The lens culinary agglutinin-reactive fraction of fetoprotein (AFP-L3), a subtype of AFP produced by malignant hepatocytes, is considered specific to hepatocellular carcinoma. AFP-L3 is isolated using immunoassay techniques and quantified using chemiluminescence on an automated platform. The proportion of AFP-L3 to total AFP can be used to diagnose early hepatocellular carcinoma. Early studies have reported that the diagnostic sensitivity of AFP-L3% for hepatocellular carcinoma ranged from 75% to 96.9%, with a specificity of 90% to 92%. The high pre-treatment serum AFP-L3% levels indicated a poor prognosis for patients with hepatocellular carcinoma, and AFP-L3% may have a significant prognostic value for patients with hepatocellular carcinoma, especially those with low AFP concentration.

A cutoff of 10% is used, and patients with chronic liver disease and an elevated AFP-l3% have a 7-fold increased risk of developing hepatocellular carcinoma within 21 months. The test is useful for early detection, particularly in the AFP range of 20 to 200 μg/L, as has been shown in patients with hepatitis C-related cirrhosis. Although AFP-l3% is useful in detecting and prognosis, the value is typically used only when AFP concentrations are elevated.

The AFP concentration is a good indicator for monitoring therapy and assessing changes in the clinical status. Elevated AFP concentration after surgery may indicate incomplete removal of the tumor or the presence of metastasis. Falling or rising AFP concentration after therapy may reveal the success or failure of the treatment regimen. A notable increase in AFP concentration in patients considered free of a metastatic tumor may indicate metastasis development.

Measuring AFP and human chorionic gonadotropin concentration aids in classifying and staging germ cell tumors. Germ cell tumors may be predominantly 1 type of cell or a mixture of various types, including seminoma, yolk sac, choriocarcinomatous elements (embryonal carcinoma), and teratoma. Serum concentrations of AFP are elevated in yolk sac tumors, whereas human chorionic gonadotropin is elevated in choriocarcinoma. Both are elevated in embryonal carcinoma. AFP is not elevated in seminomas, whereas human chorionic gonadotropin is elevated in 10% to 30% of patients with syncytiotrophoblastic tumor cells. Neither marker is elevated in teratoma.

One or both of the markers are elevated in about 90% of patients with non-seminomatous testicular tumors. Elevations are noted in less than 20% of patients with stage I, 50% to 80% with stage II, and 90% to 100% with stage III. These markers correlate with tumor volume and the prognosis of the disease. The combined use of these markers is useful in monitoring patients with germ cell tumors: elevation of either marker indicates the recurrence of the disease or the development of metastasis. The effectiveness of chemotherapy can be assessed by calculating the decrease in the concentration of both markers using the half-lives of AFP (5 days) and human chorionic gonadotropin (12 to 20 hours).          

What do the results mean?

If you haven't been diagnosed with cancer, test results that show:

- High levels of AFP may be a sign of cancer of the liver, ovaries, or testicles. But having a high AFP level doesn't mean you have cancer or that you will get cancer. Liver injury and liver diseases that aren't cancer can also cause high AFP levels. Less often, high levels of AFP may be a sign of other cancers, including lymphoma or lung cancer. Your provider will use your medical history and other test results to make a diagnosis. 

- Normal levels of AFP mean you're less likely to have cancer that causes high AFP levels. But a normal test result doesn't rule out cancer because some people with these cancers have normal AFP levels. 

If you're being treated for a cancer that increased your AFP levels, you may be tested several times during treatment. Your provider will look at all your AFP test results to see how your levels have changed over time. If your results show:

- Your AFP levels are increasing, it may mean that your treatment isn't working;

- Your AFP levels are decreasing, it may mean your treatment is working;

- Your AFP levels have stayed the same, it may mean your disease is stable and hasn't gotten better or worse.

If you've finished treatment for cancer that caused high AFP levels and your test results are:

- Not normal, it may mean that you still have some cancer in your body;

- Higher now than they were shortly after treatment, it may mean your cancer is growing again.

If you've finished treatment for cancer that caused high AFP levels and your test results are:

- Not normal, it may mean that you still have some cancer in your body;

- Higher now than they were shortly after treatment, it may mean your cancer is growing again.

If you have a long-lasting liver disease that's not cancer, you may need other tests to check for liver cancer if your test results show a sudden increase in AFP or your level is very high.

Is there anything else to know about an AFP test?

In more developed countries, the most common AFP tumor marker test measures all forms of AFP in the blood. The AFP form called L3 is a less common AFP test may be used to check the risk of liver cancer in people who have chronic liver disease. An AFP-L3 percent test (AFP-L3%) compares the amount of L3 to the amount of total AFP in the blood. If the portion of L3 increases, it may mean that one might have a high risk of developing a serious form of the most common liver cancer called hepatocellular carcinoma.

As mentioned before, AFP tests are often part of a group of prenatal tests called multiple marker or triple screen tests. These tests can help diagnose Down syndrome, trisomy 18 (Edwards syndrome), and other genetic disorders. A triple screen test includes tests for:

- Alpha-fetoprotein (AFP)

- Human chorionic gonadotropin (HCG), a hormone produced by the placenta

- Estriol, a form of estrogen made by the baby and the placenta

In some cases, a fourth test is included, called an inhibin A test, which helps diagnose Down syndrome.

If you have a high risk for having a baby with certain birth defects, the doctor may also recommend a test called prenatal cell-free DNA (cfDNA) screening. This is a blood test can can be done as early as the 10th week of pregnancy. It can show if the baby has a higher chance of having Down syndrome or certain other genetic disorders.