In this chapter we’ll discuss how your body fights the hepatitis B and C viruses, and how the effects of this “battle” and other clues are used to diagnose these diseases, to tell you how you are responding to therapy, or simply to see how your health is when you have chronic hepatitis.
- 1 – How are hepatitis B and C diagnosed?
- 2 – What do different tests mean?
- 3 – What should I do now?
- 4 BY ANDREW F. BRANCA AND MALORYE ALLISON
- 5 How your body fights the virus
- 6 How doctors test for hepatitis
- 7 What should I do now?
- 8 Dialogue Box: START TALKING TO YOUR DOCTOR
- 9 KEY WORDS
- 10 QUIZ
- 11 ACTION STEPS
– How are hepatitis B and C diagnosed?
– What do different tests mean?
– What should I do now?
BY ANDREW F. BRANCA AND MALORYE ALLISON
Finding better ways to track down the different hepatitis viruses, through new tests, has been a very important task in medicine over the last couple of decades. Doctors needed more accurate tests to help them find out who is infected, to determine whether an infection is old or new, and to measure the amount of damage the infection has caused to the liver.
How your body fights the virus
Your immune system is designed to fight off infection, including viral infection, in several ways. One of your body’s main defenses is to produce antibodies, which are like special forces designed to attack just that particular virus or bacteria. These tiny molecules can stick to viruses and prevent them from attaching to and infecting a healthy cell in the first place.
Antibodies also help your body clear the viruses from the bloodstream. A different antibody is produced for each different infection, and your body makes many copies of that antibody. Unfortunately, though, due to the differences in the viruses, the antibodies our bodies produce against hepatitis B do a much better job than the ones we produce against hepatitis C. As a result, the body is usually less effective at killing off hepatitis C, and more patients develop the chronic form of hepatitis C than of hepatitis B.
The virus may not trigger the immune system until several weeks after first entering the body, so it can take a long time for antibodies to appear. And often it is only when the virus begins causing enough damage to the body’s cells to trigger the immune system that symptoms occur – usually about 4 to 6 weeks after someone is infected.
Even before an infected person starts feeling symptoms, he or she is infectious to others. In fact, people with hepatitis B or hepatitis C may be able to infect other people as soon as 2 weeks after they themselves have become infected, whether or not they have symptoms.
How doctors test for hepatitis
In many cases, particularly with hepatitis C, the infected person will have no symptoms. Many of these people find out that they are infected with hepatitis years later, while having a routine physical exam, or perhaps if their blood is tested while buying life insurance, obtaining a marriage certificate, undergoing fertility counseling, or donating blood. The alanine aminotransferase (ALT) test, which measures the level of ALT in your blood, is sometimes used in these cases. An elevated level of ALT is a sign of inflammation in the liver. (The ALT test is one of several liver enzyme tests. It is lso often used to follow the treatment of hepatitis, to check if your disease is progressing, or if your treatment is working.)
To confirm that hepatitis B or C is what is causing the elevated ALT level, doctors must check your blood for signs of the virus, or for immune cells that the body produces in response to it. Each of several tests tells something different about the “natural history” of your exposure to a hepatitis virus.
For hepatitis B, the most common test measures the hepatitis B surface antigen (HBsAg) – a little piece of the virus’s outer coat that acts like a “red flag” signaling that the virus is in the blood. If you are feeling quite ill, and you have a positive HBsAg test, your infection may be new and active.
But if you are not feeling badly at all, it may be that you have had the disease for a while and it has become chronic. Your doctor has other tests, including the hepatitis B e antigen (HBeAg), the hepatitis B core antibody-IgM (anti-HBc-IgM), the hepatitis B core antibody-IgG (anti-HBc-IgG), the hepatitis B e antibody test (anti-HBeAg), and the HBV-DNA test, that will help determine if the infection is old or new, and whether you are still successfully fighting it off, or if you need treatment and are still infectious to other people. (See Chapter 4 for a discussion of how the virus is spread.)
For hepatitis C, your blood is tested for antibodies to the hepatitis C virus using the enzyme-linked immunosorbent assay (ELISA). (Remember, the antibodies your body produces against hepatitis B are much better at killing the virus than those directed at hepatitis C. So finding antibodies to hepatitis B in your blood might mean your body is still fighting, or has killed, the virus. But finding antibodies to hepatitis C probably means you are still infected.)
Once your body has encountered a virus, and made antibodies to it, it keeps the antibodies around just in case the virus comes back, sometimes for decades or longer. For this reason, finding antibodies doesn’t answer all of your doctor’s questions about your hepatitis C infection.
To find out more, your doctor may give you the recombinant immunoblot assay test (RIBA), which is another way of measuring the presence of various antibodies to hepatitis C in the blood, or you may be given a polymerase chain reaction (PCR) test that tells your doctor how much virus is in your blood. (The PCR test for HCV is called the HCV-RNA test.) These tests are often used only to confirm your diagnosis, or to follow up on your progress.
Another common test used is the liver biopsy, in which a small piece of liver is removed (too tiny to affect how your liver works) and examined. Many physicians do a liver biopsy whenever a patient has a high ALT, suggesting the liver is inflamed, to help them confirm what exactly is causing this problem and how serious it is. Others think it is better to use other means to confirm whether or not you have hepatitis, and they may use the liver biopsy later, to see if your disease is progressing or if your treatment is helping. If you already have clear signs of advanced liver disease, there may be no need to do a biopsy.
Your doctor has other tests available, too. Don’t be afraid to ask what tests he or she has done, what other tests are available, and what they may tell you about your condition.
What should I do now?
If you’ve just learned you have hepatitis, consider asking your doctor about the amount of the virus in your blood, and what this viral level means for treatment.
Dialogue Box: START TALKING TO YOUR DOCTOR
Patient: When we last met you told me I had hepatitis. I’ve had some time to think about this, and I have a lot of questions. First of all, is it clear that I have an active infection, or was this a past infection that is over now?
Doctor: The test showed that you have active hepatitis C in your body right now.
Patient: What tests have you done so far? What do they tell you about how serious my infection is, and how my liver is working?
Doctor: We have just started looking at that, and I won’t know for a while.
Patient: Can you please review for me which tests you plan to do, and what each one means?
(Doctor and patient review tests and their meanings together.)
Patient: Thank you. How will I find out the results of these tests? Will we discuss the results and my options?
Doctor: You need to make an appointment to come back and get the test results. We can review their meanings then.
Patient: Good, I need as much information as I can get about my condition, and this conversation has helped me a lot. I appreciate your taking the time to explain this to me.
Acute Hepatitis = A hepatitis infection that only lasts a short time – less than 6 months.
Alanine Aminotransferase (ALT) = One of several liver enzymes – a type of protein molecule. Persistent elevation of the ALT in your blood indicates that your liver may be inflamed.
Antibody = A type of immune protein molecule that is produced when bacteria or viruses enter the body. A specific “brand” off antibody is manufactured against each invader.
Chronic Hepatitis = A hepatitis infection that lasts a long time – from 6 months to the rest of your life.
Hepatitis B e Antigen (HBeAg) = This test measures the hepatitis B e antigen – a little piece of the virus’s outer coat. Your doctor uses this test to tell how “active” the virus is in your blood, and how infectious your blood is to other people.
Hepatitis B Surface Antigen (HBsAg) = This test measures the hepatitis B surface antigen (HBsAg) – another piece of the virus’s outer coat. This test is the most common test used to confirm that you have a hepatitis B infection. It does not tell how infectious you are or how much virus is in your blood.
Hepatitis B DNA (HBV DNA) = A test that determines the level of actual virus in your blood. It is done by using a process called the polymerase chain reaction (PCR).
Hepatitis C Antibody (anti-HCV) = A test for hepatitis C antibodies, done using the enzyme-linked immunosorbent assay (ELISA), tells your doctor if you have been exposed to the hepatitis C virus.
Hepatitis C RNA (HCV RNA) = This test determines the level of actual hepatitis C virus in your blood. It can also be done using the PCR.
Liver Biopsy = During a liver biopsy, a small piece of your liver is taken out. This test may be done early on to decide if there is any liver damage and how serious it is. It can also be done later to see if your disease is progressing or if treatment is working.
Recombinant Immunoblot Assay (RIBA) = Another way of measuring the presence of antibodies against hepatitis C in your blood.
Virus = A tiny microorganism, even smaller than bacteria, that can cause sickness in humans and cannot be treated with antibiotics.
Q. How does the body fight infection?
A. One of the main ways the body fights infection is by producing antibodies that attack the invader.
Q. How soon after infection can a person infect someone else?
A. A person infected with hepatitis B or C may become infectious to others as soon as 2 weeks after being infected themselves.
Q. What are the most common tests for hepatitis?
A. The hepatitis B surface antigen test (HBsAg) tells you if you have hepatitis B virus in your blood. An antibody test for hepatitis C tells you that you have been exposed to hepatitis C and it is very likely the virus is still present. The alanine aminotransferase (ALT) simply tells you whether or not your liver is inflamed. Lastly, a polymerase chain reaction (PCR) test (HBV DNA or HCV RNA) may determine how much virus is in your blood.
– Ask your doctor about the level of virus in your blood, what this level means for your treatment, and the chance you might infect others.
– Discuss all your other test results and what they mean with your doctor.
– Ask your doctor how much experience he or she has in treating hepatitis patients and whether he or she recommends that you see a hepatologist – a specialist in liver disease – for your care.