Glossary of Terms Related to Hepatitis B
Albumin: A protein made in the liver that assists in maintaining blood volume in the arteries and veins. If the liver is damaged, then the albumin can drop to very low levels, which may cause fluid to leak into the tissues from the blood vessels, resulting in edema or swelling. In acute liver failure, there is an accumulation of fluid in the abdomen that is known as "ascites".
Alpha-fetoprotein (AFP): A protein secreted into the blood during pregnancy or when cancer cells are present. Increased levels may indicate the development of liver cancer, which is why the simple AFP blood test is included in the regular monitoring of those which chronic HBV.
Antibody: A protein molecule produced by the immune system in response to a foreign body, such as the hepatitis B virus and its antigens. Antibodies can be produced in response to a vaccine or to a natural infection. They circulate in the blood to protect against future infections. Hepatitis B blood tests often look for the surface, core and “e” antibody.
Anti-HCV (antibody to hepatitis C virus): The antibody produced against the hepatitis C virus (HCV). Its presence in the bloodstream often indicates HCV infection. This antibody has not been shown to protect people against hepatitis C, nor does it show a resolved hepatitis C infection.
Antigen: A protein on the surface of a virus, bacteria or cell that can stimulate the immune system to produce antibodies as a defense mechanism. For example, blood tests for hepatitis B look for the surface, core and “e” antigen.
Ascites: A large, abnormal accumulation of fluid in the abdomen that can occur due to liver failure, cirrhosis and liver cancer. This condition requires immediate medical attention.
Asymptomatic: Refers to infection or disease without signs of illness. Many patients with hepatitis B or C do not have any symptoms during a new or chronic infection; they are considered to be asymptomatic.
Bilirubin: The liver usually clears this end product of hemoglobin (the portion of the red blood cell that carries oxygen in the blood) when it normally breaks down. If the liver is damaged and bilirubin accumulates in the blood, a person can become jaundiced (yellowed eyes and skin).
Bloodborne Pathogens: Substances present in the blood that can cause infection or disease. Hepatitis B and h\C viruses and HIV are bloodborne pathogens because they are spread through direct contact with blood and body fluids and can cause an infection.
Chronic Hepatitis B Infection: A patient who tests positive for the hepatitis B virus for more than six months is considered to have a chronic hepatitis B infection.
Cirrhosis: A serious liver condition characterized by irreversible scarring of the liver that can lead to liver failure and death. Alcohol and chronic viral hepatitis (such as chronic hepatitis B and C) can cause continuous inflammation of the liver, which can lead to excess scar formation or fibrosis. Scarring results in the loss of liver cells and impairs liver function.
Clinical Trials: Carefully controlled studies that are conducted in humans who volunteer to test the effectiveness and safety of new drugs, medical products or techniques. All drugs in the United States undergo three phases of clinical trials before being approved for general use.
Clotting Factors: Proteins made in the liver that are important in maintaining normal blood clotting. Disruption in the blood's ability to clot may indicate that the liver is not creating enough clotting factors. A severe shortage in clotting factors may indicate that a liver transplant is needed.
Complete Blood Count (CBC): A test that measures the number of red blood cells, white blood cells, the amount of hemoglobin, hematocrit, and platelets. Low white blood cell and platelet counts may indicate liver scarring.
Coinfection: A coinfection occurs when there are simultaneous infections by more than one virus. For example, an individual can be coinfected with both the hepatitis B and C virus.
DNA Polymerase: An enzyme essential to the replication of the hepatitis B virus. Most of the current antiviral drugs used against HBV interfere with the DNA polymerase in order to stop the virus from reproducing.
Decompensated Cirrhosis: A late-stage cirrhosis accompanied by abnormal blood tests and other complications. At this stage of the disease, evaluation for liver transplant becomes an option.
E-Antibody (HBeAb or anti-HBe): Produced by the immune system temporarily during acute HBV infection or consistently during or after an increase in viral replication. Spontaneous conversion from e-antigen to e-antibody (a change known as "seroconversion") is a predictor of long-term clearance of HBV in patients undergoing antiviral therapy.
Encephalopathy: Serious brain function abnormalities experienced by some patients with advanced liver disease. Symptoms most commonly include confusion, disorientation, insomnia, and may progress to a coma.
Fatty Liver: Refers to a condition where fat accumulates in liver cells and makes up more than 5 to 10 percent of the liver’s weight. This accumulation of fat does not generally cause liver damage, but it needs to be monitored. In some cases, it can accelerate liver damage in people with hepatitis B. There are two types of fatty liver: alcoholic liver disease (ALD) and nonalcoholic fatty liver disease (NAFLD).
Fibrosis (hepatic): Growth of fibrous tissue in the liver where there is usually liver cell damage or destruction. Fibrosis can lead to cirrhosis, an even more serious liver disease.
Genotype: A pattern of genetic information that is unique to an individual or group. The hepatitis B virus has a pattern of genetic information unique to itself. Doctors may determine the genotype to help decide the best treatment. Currently, there are seven known genotypes for hepatitis B; however, its significance is not well established for clinical use. Hepatitis C treatment can be based on genotype.
Hepatitis: Refers to “inflammation of the liver”, which can be caused by many things such as viruses, bacterial infections, trauma, adverse drug reactions, or alcoholism. Inflammation of the liver caused by viruses is called “viral hepatitis”. There are many different viruses that attack the liver, including hepatitis A, B, C, D, E, F, G
Hepatitis B Surface Antigen (HBsAg): The surface protein of the hepatitis B virus that is used as a marker to detect infection. If this blood test is positive, then the hepatitis B virus is present.
Hepatitis B Surface Antibody (HBsAb or anti-HBs): The antibody formed in response to the surface protein of the hepatitis B virus. It can be produced in response to vaccination or recovery from an actual hepatitis B infection. If this test is positive, then the immune system has successfully developed a protective antibody against the hepatitis B virus that provides long-term immunity.
Hepatitis B Core Antibody (HBcAb or anti-HBc): This antibody only refers to a part of the virus itself; it does not provide any protection or immunity against HBV. This test is often used by blood banks to screen blood donations. A positive test indicates a person may have been exposed to the hepatitis B virus, but the result can only be confirmed in relationship to the above two tests.
Hepatitis B “e” Antigen (HBeAg): A marker of a high degree of hepatitis B infectivity, it correlates with a high level of viral replication. It is primarily used to help determine the clinical management of patients with chronic hepatitis B infection.
Hepatitis B Immune Globulin (HBIG): A medication that is given as a “post-exposure” treatment to prevent hepatitis B. This means that HBIG is given after a person has been exposed to potentially infected blood or infected bodily fluids, which can include but is not limited to - contact with blood or through a needle-stick, infants born to infected women, and through sexual contact or close household contact with an infected person. HBIG is often used as a post-liver transplant treatment.
HBV DNA: A marker of viral replication. It indicates how much viral load or hepatitis B virus (HBV) is in a patient. High levels of HBV DNA mean a patient’s blood and body fluids are very infectious. HBV DNA, usually measured in international units per milliliter (IU/mL), is used to assess and monitor the treatment of patients with chronic HBV infection. Some tests may measure HBV DNA in copies per milliliter. There are about 5.8 copies in every one international unit.
Hepatocellular Carcinoma (HCC): A malignant tumor of the liver, otherwise known as liver cancer. Chronic hepatitis B and C infections may increase the risk of developing liver cancer.
Hepatocyte: A liver cell.
Hepatologist: A doctor who specializes in the study and treatment of liver disease. Ideally, patients with chronic hepatitis B or C should see a “hepatologist”.
Hepatology: The field of medicine that focuses on diseases of the liver. It is a sub-specialty within gastroenterology.
Histology: The field of medicine that studies tissue under the microscope. Histological evaluations of liver biopsy samples are helpful in the diagnosis and monitoring of possible liver damage in chronic HBV and HCV carriers.
IgG anti-HBc: A subclass of the hepatitis B core antibody (HBcAb or anti-HBc) is a marker of past or current infection with HBV. If it and HBsAg are both positive (in the absence of IgM anti-HBc), this indicates chronic HBV infection.
IgM anti-HBc: A subclass of the hepatitis B core antibody (HBcAb or anti-HBc). Positivity indicates recent infection with HBV (less than 6 months). Its presence indicates acute infection.
Jaundice: A condition characterized by yellowing of the skin and eyes. Jaundice is a symptom of many disorders, which can include viral hepatitis, alcoholism, poisoning, and abnormal breakdown of red blood cells or gallbladder disease. This symptom requires immediate medical attention.
Liver Enzymes: Proteins that catalyze chemical reactions needed for bodily functions. Levels of certain enzymes, such as ALT and AST are higher when the liver is injured, as they leak into the bloodstream when the cell is injured or destroyed.
Liver Function Tests (LFT’s): Refers to a group of blood tests used to evaluate the function of the liver. The tests can be used to diagnose and monitor chronic viral hepatitis as well as other liver diseases. The two most common tests include the following liver enzymes:
- Aspartate Aminotransferase (AST): An enzyme that is released into the blood by the liver and other tissues or organs. It is generally used as a marker for liver or biliary damage.
- Alanine Aminotransferase (called either ALT or SGPT): An enzyme that is released into the blood by damaged liver cell. It is used as a marker for liver cell damage. The ALT test is considered to be a more accurate reflection of liver inflammation than AST because other organs such as the heart can also produce AST. (e.g. the level of AST will increase on a blood test during a heart attack). ALT levels are included in the regular monitoring of all chronic hepatitis B patients; this test can also useful in deciding whether a patient would benefit from therapy or evaluating the effectiveness of an ongoing treatment.
PCR (polymerase chain reaction): A highly sophisticated scientific method of detecting the presence of hepatitis B virus DNA or hepatitis C virus RNA in the blood. This test can be conducted on the same sample of blood obtained with the hepatitis B panel of blood tests; no extra doctor’s visit is needed.
Perinatal Transmission (vertical transmission): The transmission of an infectious disease, such as hepatitis B, from a mother to her newborn. The most important mode of HBV transmission globally is from the mother to her newborn baby. If a pregnant woman is chronically infected with hepatitis and is also HBeAg-positive, her newborn baby has a 90 percent chance of becoming infected and developing lifelong, chronic hepatitis B infection. Of these children, about 25 percent will die later from chronic liver disease or liver cancer. To prevent these outcomes, all pregnant women should be tested for hepatitis B, and all newborns of infected mothers should receive the first dose of vaccine and a dose of HBIG within 12 hours after delivery. Pregnant women with high viral lods (exceeding 200,000 IU/mL) may be treated with antivirals during her pregnancy to reduce the risk of perinatal transmission.
Platelets: Cells that are produced in the bone marrow. Platelets control bleeding by causing the blood to clot. The liver produces the clotting factors involved in this process. If the liver is damaged, then clotting will also be impaired.
Seroconversion: A change in status from antigen positive/antibody negative to antigen negative/antibody positive. For example, seroconversion of e-antigen positive to e-antibody positive indicates a significant decrease in the amount of hepatitis B virus. Seroconversion of hepatitis B surface antigen positive/surface antibody negative to surface antigen negative/surface antibody positive connotes being "cured" of a chronic HBV infection since the virus has been cleared from the liver and bloodstream.
Vaccine: A medication that stimulates the production of antibodies to protect against a specific disease. There is a hepatitis A vaccine, hepatitis B vaccine, and a combination vaccine that provides protection against both hepatitis A and B at the same time.
Viral hepatitis: Inflammation of the liver caused by viruses that specifically attack the liver: hepatitis A, B, C, D, E, F, and G viruses.
Viral Load: Measurement of the actual amount of virus in the bloodstream such as hepatitis B and C.
Virus: A tiny microorganism, smaller than bacteria, which can invade the body and cause disease. A virus can reproduce itself exactly or mutate and make small changes. The ability of a virus to change slightly in each infected person is why treatment of viral diseases is so difficult.