Post by Chang Sha on Aug 27, 2010 23:55:43 GMT -5
August 27, 2010
A. Hepatitis is an inflammation of the liver characterized by the presence of inflammatory cells in the tissue of the organ. The condition can be self limiting or can progress to fibrosis and cirrhosis. Hepatitis is acute when it lasts less than six months and chronic when it persists longer.
B. What are Hepatitis Tests and Diagnosis?
B1. Bilirubin is one of the most important factors indicative of hepatitis. It is a red-yellow pigment that is normally metabolized in the liver and then excreted in the urine. Enzymes known as aminotransferases, particularly aspartate (AST) and alanine (ALT) are released when the liver is damaged. To identify the particular virus causing hepatitis, blood tests called radioimmunoassays are performed. Typically, radioimmunoassays identify particular antibodies, which are molecules in the immune system that attack specific antigens. A liver biopsy may be performed for acute viral hepatitis caught in a late stage or for severe cases of chronic hepatitis.
B2. Blood Tests. Hepatitis B virus (HBV) is diagnosed by checking for substances in the blood that show whether the infection is active or has occurred in the past. The tests look for different signs of infection (markers):
B2.1. Blood Test Overview
B2.2. Most common HBV tests:
B2.3. Other less frequent HBV tests:
B3. Liver Biopsy for Hepatitis. In cases of chronic hepatitis, the extent of the damage to the liver is established via a tissue sample from the liver (biopsy). As most liver diseases affect the entire organ uniformly, the small sample obtained by biopsy, generally performed under a local anesthetic, will show any abnormalities.
B4. Liver Proteins and Hepatitis:Albumin, prothrombin, and immunoglobulins are checked and abnormal levels are indicative of severe liver disorder. Prothrombin times, because the liver produces many of the clotting factors required to stop bleeding needs to be determined.
B5. Liver Function Tests:These tests show how well the liver is functioning but will not accurately assess the many and varied functions for which liver is responsible. Tests do check the level of liver enzymes, transaminases and cholestatic enzymes, bilirubin and liver protein levels. High levels of transaminases in the blood do not always reveal how badly the liver is inflamed or damaged. Elevated levels can also occur in genetic liver disease, liver tumors and heart failure. The normal ranges of AST and ALT transaminases are around 0 to 40 IU/L and 0 to 45 IU/L respectively.
B6. If you do not have hepatitis B, a vaccine is available to prevent an HBV infection.
A. Hepatitis is an inflammation of the liver characterized by the presence of inflammatory cells in the tissue of the organ. The condition can be self limiting or can progress to fibrosis and cirrhosis. Hepatitis is acute when it lasts less than six months and chronic when it persists longer.
B. What are Hepatitis Tests and Diagnosis?
B1. Bilirubin is one of the most important factors indicative of hepatitis. It is a red-yellow pigment that is normally metabolized in the liver and then excreted in the urine. Enzymes known as aminotransferases, particularly aspartate (AST) and alanine (ALT) are released when the liver is damaged. To identify the particular virus causing hepatitis, blood tests called radioimmunoassays are performed. Typically, radioimmunoassays identify particular antibodies, which are molecules in the immune system that attack specific antigens. A liver biopsy may be performed for acute viral hepatitis caught in a late stage or for severe cases of chronic hepatitis.
B2. Blood Tests. Hepatitis B virus (HBV) is diagnosed by checking for substances in the blood that show whether the infection is active or has occurred in the past. The tests look for different signs of infection (markers):
B2.1. Blood Test Overview
- Antigens are markers made by bacteria or viruses. So the presence of HBV antigens means that the virus is in the body.
- Antibodies are proteins produced by the body to fight infection. The presence of HBV antibodies means that you have been exposed to the hepatitis B virus at some time. But you could have been infected long ago and gotten better, or you may have a current infection.
- Genetic material ( DNA ) of the hepatitis B virus shows that the virus is in the body. The amount of DNA can help determine how severe the infection is and how easily the HBV infection can be spread.
B2.2. Most common HBV tests:
- Hepatitis B surface antigen (HBsAg) is the earliest sign of an active hepatitis B infection. This antigen may be present before symptoms of an HBV infection are present. If this antigen is present for more than 6 months, then you probably have a chronic (long-term) HBV infection. This means you can spread HBV to others throughout your life.
- Hepatitis B surface antibody (HBsAb) usually appears about 4 weeks after HBsAg disappears. The presence of this antibody means that the infection is at the end of its active stage and you cannot pass the virus to others (you are no longer contagious). This antibody also protects you from getting HBV again in the future. The test is done to determine the need for vaccination—the antibody will be present after receiving the HBV vaccine series, showing that you have protection (immunity) from the virus. Occasionally your test may show that you have both the HBsAb antibodies and HBsAg antigen. In this case you are still contagious.
- Hepatitis B e-antigen (HBeAg) is an HBV protein that is only present during an active HBV infection. This test determines how contagious you are. Testing for this antigen can also be used to monitor the effectiveness of treatment for HBV.
- HBV DNA testing checks for genetic material ( DNA ) from the hepatitis B virus. The HBV DNA tests measure how much genetic material is present. A high level of HBV DNA means that the virus is multiplying in your body and you are very contagious. If you have a chronic HBV infection, an elevated viral DNA level means you are at an increased risk for liver damage and may want to consider treatment with antiviral medicine. Testing for HBV DNA is also used to check the effectiveness of treatment for long-term (chronic) HBV infection. HBV DNA testing is a more sensitive test than HBeAg (above) for detecting HBV in the blood.
B2.3. Other less frequent HBV tests:
- Hepatitis B core antibody (HBcAb) is an antibody to the hepatitis B core antigen that appears about 1 month after an active HBV infection. It can be found in people who had an infection in the past and in those with long-term (chronic) HBV. It usually is present for life. Blood banks test for this antibody when screening donated blood for hepatitis B.
- Hepatitis B core antibody IgM (HBcAbIgM) is another antibody to the hepatitis B core antigen. It indicates an HBV infection that has occurred within the last 6 months.
- Hepatitis B e-antibody (HBeAb) shows that the active stage of an acute HBV infection is almost over, and your risk of being contagious is greatly reduced.
B3. Liver Biopsy for Hepatitis. In cases of chronic hepatitis, the extent of the damage to the liver is established via a tissue sample from the liver (biopsy). As most liver diseases affect the entire organ uniformly, the small sample obtained by biopsy, generally performed under a local anesthetic, will show any abnormalities.
B4. Liver Proteins and Hepatitis:Albumin, prothrombin, and immunoglobulins are checked and abnormal levels are indicative of severe liver disorder. Prothrombin times, because the liver produces many of the clotting factors required to stop bleeding needs to be determined.
B5. Liver Function Tests:These tests show how well the liver is functioning but will not accurately assess the many and varied functions for which liver is responsible. Tests do check the level of liver enzymes, transaminases and cholestatic enzymes, bilirubin and liver protein levels. High levels of transaminases in the blood do not always reveal how badly the liver is inflamed or damaged. Elevated levels can also occur in genetic liver disease, liver tumors and heart failure. The normal ranges of AST and ALT transaminases are around 0 to 40 IU/L and 0 to 45 IU/L respectively.
B6. If you do not have hepatitis B, a vaccine is available to prevent an HBV infection.