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Viral Hepatitis and Liver Disease

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Understanding Lab Tests: Entire Lesson

for Veterans and the Public

Understanding Lab Tests: Entire Lesson - Hepatitis C for Patients

Understanding Lab Tests: Overview

Once you've been diagnosed with hepatitis C, your VA provider probably will order several to learn about your liver health and your overall health. These tests will help determine which drug therapy is most appropriate to treat your hepatitis C.

Some tests are repeated while you are on treatment to see if the treatment is working and to monitor for side effects. 10-12 weeks after you complete the Hepatitis C treatment, a final test is ordered to see if the treatment was successful, and if you have been cured. This is a very important test and should not be missed.

If you have scarring of the liver, or cirrhosis, you may be asked to complete tests on a regular basis. These tests will monitor your liver health and guide additional treatments to prevent worsening liver function.

In the following sections, you can learn about the tests, why your provider may have ordered them, and what the results mean.

Normal values for laboratory tests can vary from one lab to another. Check with your provider on the normal range for your lab tests.

Tests of liver function

If you have hepatitis C, most likely, your provider will check blood tests of your liver. There are many different liver tests and it is helpful to know what each of them means. Here, we explain common liver blood tests and how to understand your results:

Liver panel

A "liver panel" usually refers to several lab tests performed as a group. Depending on the provider or the laboratory, a liver panel usually includes tests for AST, ALT, bilirubin, and alkaline phosphatase.

Liver enzymes

Usually, the term "liver enzymes" refers to the AST and the ALT.

Liver function tests (LFTs)

The phrase "liver function tests" or "LFTs" is commonly used by patients and providers.

Liver function is best measured by the PT, INR and albumin. Therefore, if you are getting a PT, INR or albumin, these tests can determine how the liver is "functioning."

ALT (SGPT)

ALT, or alanine aminotransferase, is one of the two liver enzymes. It is sometimes known as serum glutamic-pyruvic transaminase, or SGPT. It is a protein made only by liver cells. When liver cells are damaged, ALT leaks out into the bloodstream and the level of ALT in the blood is elevated.

signs of an unhealthy liver

Scroll over image to see an animation of liver enzymes leaking into the blood.

Explanation of test results:

A high ALT level often means there is some liver damage, but it may not be related to hepatitis C. It is important to realize the ALT level goes up and down in most patients with hepatitis C. The ALT level does not tell you how much liver damage there is, and small changes are common. Changes in the ALT level do not mean the liver is doing any better or any worse. The ALT level does not indicate how much scarring (fibrosis) is in the liver and it does not predict how much liver damage will develop. A normal ALT does not mean the hepatitis C is cured.

Other things to know:

  • Many patients with hepatitis C will have a normal ALT level.
  • Patients can have very severe liver disease and cirrhosis and still have a normal ALT level.
  • When a patient takes treatment for hepatitis C, it is helpful to see if the ALT level goes down.

AST (SGOT)

AST, or aspartate aminotransferase, is one of the two liver enzymes. It is also known as serum glutamic-oxaloacetic transaminase, or SGOT. AST is a protein made by liver cells. When liver cells are damaged, AST leaks out into the bloodstream and the level of AST in the blood becomes elevated. AST is different from ALT because AST is found in parts of the body other than the liver—including the heart, kidneys, muscles, and brain. When cells in any of those parts of the body are damaged, AST can be elevated.

Explanation of test results:

A high AST level often means there is some liver damage, but it is not necessarily caused by hepatitis C. A high AST with a normal ALT may mean that the AST is coming from a different part of the body. It is important to realize that the AST level in most patients with hepatitis C goes up and down. The exact AST level does not tell you how much liver damage there is, or whether the liver is getting better or worse, and small changes should be expected. However, for patients receiving treatment for hepatitis C, it is helpful to see if the AST level goes down.

Other things to know:

  • The AST level is not as helpful as the ALT level for checking the liver.
  • Many patients with hepatitis C will have a normal AST level.
  • Patients can have very severe liver disease or cirrhosis and still have a normal AST level.

Bilirubin

Bilirubin is a yellowish substance that is created by the breakdown (destruction) of hemoglobin, a major component of red blood cells.

Explanation of test results:

As red blood cells age, they are broken down naturally in the body. Bilirubin is released from the destroyed red blood cells and passed on to the liver. The liver releases the bilirubin in fluid called bile. If the liver is not functioning correctly, the bilirubin will not be properly released. Therefore, if the bilirubin level is higher than expected, it may mean that the liver is not functioning correctly.

Other things to know:

  • Levels of bilirubin in the blood go up and down in patients with hepatitis C.
  • When bilirubin levels remain high for prolonged periods, it usually means there is severe liver disease and possibly cirrhosis.
  • High levels of bilirubin can cause jaundice (yellowing of the skin and eyes, darker urine, and lighter-colored bowel movements).
  • Elevated bilirubin levels can be caused by reasons other than liver disease.

Albumin

Albumin is a protein made by the liver. Albumin prevents fluid from leaking out of blood vessels into tissues.

Explanation of test results:

A low albumin level in patients with hepatitis C can be a sign of cirrhosis (advanced liver disease). Albumin levels can go up and down slightly. Very low albumin levels can cause symptoms of edema, or fluid accumulation, in the abdomen (called ascites) or in the leg (called edema).

Other things to know:

  • A low albumin level can also come from kidney disease, malnutrition, or acute illness.
  • A low albumin level causing fluid overload is often treated with diuretic medications, or "water pills."

Prothrombin time

Prothrombin is a protein made by the liver. Prothrombin helps blood to clot. The "prothrombin time" (PT) is one way of measuring how long it takes blood to form a clot, and it is measured in seconds (such as 13.2 seconds). A normal PT indicates that a normal amount of blood-clotting protein is available.

Explanation of test results:

When the PT is high, it takes longer for the blood to clot (17 seconds, for example). This usually happens because the liver is not making the right amount of blood clotting proteins, so the clotting process takes longer. A high PT usually means that there is serious liver damage or cirrhosis. A high PT may indicate there is a higher risk for internal bleeding from the upper part of the GI tract (esophagus, stomach).

Other things to know:

  • Some patients take a drug called Coumadin (warfarin), which elevates the PT for the purpose of "thinning" the blood. This is not related to having liver disease because it is the Coumadin causing the PT to be high.
  • The test called INR measures the same factors as PT and is used instead of PT by many providers. See "INR."

Alkaline phosphatase

Alkaline phosphatase (often shortened to alk phos) is an enzyme made in liver cells and bile ducts. The alk phos level is a common test that is usually included when liver tests are performed as a group.

Explanation of test results:

A high alk phos level does not reflect liver damage or inflammation. A high alk phos level occurs when there is a blockage of flow in the biliary tract or a buildup of pressure in the liver--often caused by a gallstone or scarring in the bile ducts.

Other things to know:

  • Many patients with hepatitis C have normal alk phos levels.
  • Hepatitis C treatment usually does not affect alk phos levels.
  • Alk phos is produced in other organs besides the liver--it is also found in the bones and the kidneys.
  • If your alk phos level is high, your provider will probably order additional tests to determine why.

INR (international normalized ratio)

International normalized ratio (INR) is blood-clotting test. It is a test used to measure how quickly your blood forms a clot, compared with normal clotting time.

Explanation of test results:

A normal INR is 1.0. Each increase of 0.1 means the blood is slightly thinner (it takes longer to clot). INR is related to the prothrombin time (PT). If there is serious liver disease and cirrhosis, the liver may not produce the proper amount of proteins and then the blood is not able to clot as it should. When your provider is evaluating the function of your liver, a high INR usually means that the liver is not working as well as it could because it is not making the blood clot normally.

Other things to know:

  • Some patients take a drug called Coumadin (warfarin), which elevates the INR, for the purpose of "thinning" the blood.
  • The INR is another way of measuring the blood-clotting time and it is easier to determine than the PT.

Platelets

Platelets are cells that help the blood to form clots. The platelet number or "platelet count" in the blood is measured as part of the complete blood count (CBC).

Explanation of test results:

Platelet counts in a patient who has cirrhosis are often low. But low platelet counts can also come from other causes, including certain medications. When the platelet count is extremely reduced, this condition is known as "thrombocytopenia." If a platelet count is too low, the patient cannot make normal clots and may bruise or bleed more easily.

Total protein

Total protein level is a measure of a number of different proteins in the blood. Total protein can be divided into the albumin and globulin fractions.

Explanation of test results:

Low levels of total protein in the blood can occur because of impaired function of the liver.

Tests of hepatitis C

If you have hepatitis C virus, you are likely to have a provider recommend a few different hepatitis C blood tests, not just one. It is helpful to understand what each of these blood tests mean. Here we explain the common blood tests of hepatitis C and the meaning of test results.

Hepatitis C antibody (HCV Ab, anti-HCV)

This is the first test for determining whether you have been infected with hepatitis C. The results will come back as either positive or negative.

Explanation of test results:

If this test result is positive, it means your body was exposed to the hepatitis C virus and made antibodies (for more information, see "Antibody" section under Associated Lab Tests). However, it does not tell you whether you are still infected with hepatitis C. If the antibody test result is positive, you should be tested for hepatitis C RNA (see "Hepatitis C RNA"), which determines whether you are chronically infected. The lab will perform this RNA test automatically if your hepatitis C antibody test is positive.

If the antibody test result is negative, it means you have not been infected with the hepatitis C virus, and further testing for hepatitis C usually is not needed.

Other things to know:

  • After a successful course of treatment for hepatitis C, the hepatitis C antibody remains detectable, but the hepatitis C RNA will be undetectable.
  • If you plan to donate blood, you will be tested for the hepatitis C antibody and will be turned away even if you do not have an active infection.
  • Any patient with a positive test result for the hepatitis C antibody should have additional tests to determine whether or not the virus is still active.

Hepatitis C RNA qualitative testing

The qualitative HCV RNA tests will report whether the hepatitis C virus is present in the bloodstream or not. The result is reported as either "detected" or "not detected."

Explanation of test results:

If a qualitative RNA test is positive (detected), then it is confirmed that the patient has chronic hepatitis C. The "qualitative" test is more accurate than the "quantitative" test because qualitative tests are able to detect very low levels of the virus.

Other things to know:

  • If a patient has a quantitative test that shows no detectable virus, but has a positive result with the qualitative test, it means there is a very low level of virus that can be detected only with the qualitative test.
  • The qualitative test will become negative during hepatitis C treatment and indicates a good response.
  • A negative qualitative test 10-12 weeks after finishing hepatitis C treatment means you are cured.
  • The qualitative test result also will be negative if the patient clears the hepatitis C virus on their own, soon after infection, or "spontaneously." If the result is still positive after 6 months, treatment should be considered.

Hepatitis C Viral Load / HCV RNA quantitative testing

The viral load of hepatitis C refers to the amount of virus present in the bloodstream. The quantitative HCV RNA tests measure the amount of hepatitis C virus in the blood. The result will be an exact number, such as "1,215,422 IU/L." Many people refer to the quantitative measurement as the hepatitis C "viral load."

Viral load tests are used to confirm active hepatitis C infection and are used during treatment to help determine response. If you have lower levels of virus in your blood when you start treatment, you may have a better chance of getting rid of the virus.

Explanation of test results:

There are 2 situations in which a quantitative test is useful:

The quantitative HCV RNA test is checked before a patient starts treatment.

For each patient, the result can be described as either a "high" viral load, which is usually >800,000 IU/L, or a "low" viral load, which is usually <800,000 IU/L. It's not uncommon to have a viral load in the millions. Today's hepatitis C treatments are very effective with both high and low viral loads. An undetectable HCV viral load 10-12 weeks after hepatitis C is completed is associated with a cure.

The quantitative HCV RNA test is used to monitor a patient who is currently on treatment.

The response to treatment is considered good when the quantitative HCV RNA measurement drops and the virus eventually becomes completely undetectable.

Other things to know:

  • The viral load measurement does not tell us anything about the severity of a patient's liver disease or the degree of fibrosis (scarring). For that information, the patient would need additional testing.
  • It is not necessary to check the viral load repeatedly during treatment.
  • If a quantitative HCV RNA result is reported as "<15 IU/L," this means that the quantitative test cannot measure the hepatitis C virus. It may mean that there is no detectable HCV RNA at all, but it may mean that the level of virus is just too low for the test to pick it up.

Hepatitis C genotype

The hepatitis C genotype is a type or "strain" of hepatitis C virus. There are 6 genotypes of hepatitis C around the world. In the United States, 3 genotypes are common:

  • Genotype 1
  • Genotype 2
  • Genotype 3

These can be further specified as:

  • Genotype 1a or 1b
  • Genotype 2a or 2b or 2c
  • Genotype 3a or 3b

A person's hepatitis C genotype does not change over time. It needs to be tested only once. If you are treated for hepatitis C, your genotype will determine your treatment plan, such as which medications are prescribed and how long the treatment will be.

Associated lab tests

Patients with hepatitis C often have a wide variety of blood tests requested by their provider. In addition to tests of hepatitis C and tests of the liver, you may have tests of your kidney, blood counts, and testing for other infections. Vaccinations to prevent other viral illness may be suggested.

It is especially important to understand these tests if you are taking hepatitis C treatments. Here we explain the meaning of some of the most common blood tests you may want to understand.

Hemoglobin

Hemoglobin is a protein within red blood cells. Hemoglobin allows red blood cells to carry oxygen to the rest of the body.

Explanation of test results:

Measuring hemoglobin levels helps to estimate the number of red blood cells in the body. A low hemoglobin level is referred to as "anemia." If hemoglobin levels are very low, patients may feel tired easily.

Other things to know:

  • The hemoglobin level is related to the hematocrit (see next screen: "Hematocrit").
  • Low hemoglobin levels can develop during treatment with ribavirin (a medication sometimes used in hepatitis C treatment).
  • Often, lowering the dosage of ribavirin will help bring the hemoglobin level back up.

Hematocrit

The hematocrit is sometimes known as "red blood cell count." The hematocrit is the percentage of red blood cells in the total contents of your blood.

Explanation of test results:

A low hematocrit is referred to as "anemia." If the hematocrit is very low, patients may feel tired easily.

Other things to know:

  • The hematocrit is directly related to the hemoglobin level (see previous screen: "Hemoglobin").
  • Low hematocrits can develop during treatment with ribavirin (a medication sometimes used in hepatitis C treatment).
  • Often, lowering the dosage of ribavirin will help bring the hematocrit back up.

Creatinine

The level of creatinine in your body is a marker of kidney function. Creatinine comes from the breakdown of creatine, a muscle protein. Properly functioning kidneys remove creatinine from the blood.

Explanation of test results:

High levels of creatinine mean that the kidneys are not functioning properly. When creatinine levels rise gradually, there are not usually any symptoms, and the higher levels can be detected only with blood tests.

Other things to know:

  • Certain medications can cause high levels of creatinine.
  • A high creatinine level is sometimes referred to as "renal insufficiency" or "acute kidney injury."

Tests for HIV, Hepatitis A and B

These are tests to determine if you have been exposed to other viruses that can cause or worsen liver disease. Vaccines for hepatitis A and B are recommended for all unvaccinated patients with hepatitis C. A positive test result for hepatitis A and B may indicate you were previously exposed or vaccinated and the results should be interpreted by your provider.

A positive test result for HIV indicates exposure to the HIV virus and requires referral to an infectious disease specialist. HIV is treatable and should be treated before HCV treatment can be provided. Hepatitis C treatments are as effective in patients with HIV as they are in patients without HIV.

AFP (Alfa-fetoprotein)

AFP is a protein that is present in patients with liver disease. AFP is also a "tumor marker" and may be used to see if a patient has liver cancer. (Liver cancer is also called hepatocellular carcinoma).

Explanation of test results:

A high level of AFP might mean that a patient has liver cancer. However, sometimes the AFP is high when there is active liver disease but no cancer. Usually, the AFP test needs to be interpreted by a doctor in combination with pictures of the liver taken with ultrasound or CT scan.

Other things to know:

  • A mildly elevated AFP level needs to be interpreted by your provider. A high AFP level may just mean you have active liver inflammation.
  • AFP can be elevated in other types of cancers and in a normal pregnancy.

Antibody

Antibodies are part of the immune system's response to infection. Once an infection has taken place, the body makes antibodies, which become detectable in the bloodstream. Different antibodies fight different infections.

Explanation of test results:

If you have a positive test result for a specific antibody, it means that your body has had an immune response to that specific infection. It does not necessarily mean you are still infected--it does mean that you were infected at some point in the past.

It is recommended to check for antibodies to hepatitis A and B in all patients with hepatitis C. If you do not have antibodies to either of these viruses, vaccinations are recommended and highly effective.