Hepatitis B (cont.)
What is the role of a liver biopsy in chronic hepatitis B?
During a liver biopsy, a small sample of liver tissue is collected and
examined under the microscope. This test is valuable because this sample
reflects the health of the liver. It can show the amount of liver injury
(inflammation or cirrhosis). Liver biopsy is not routinely needed to diagnose
hepatitis B, but it is used for monitoring the progression of liver damage in
people with chronic hepatitis and helping to choose or evaluate treatment
options.
What is the natural course of chronic hepatitis B?
The course of chronic hepatitis B is variable and depends on several factors.
These factors are the patient's age at which the infection began, the extent of
viral multiplication, and the immune system's ability to control the infection.
The infection can progress from an:
- immune tolerant phase (in which the immune system ignores the virus)
- immune clearance phase (in which the immune system attempts to eliminate
the virus)
- quiescent phase (in which the virus is less active)
Immune tolerant phase
For individuals infected at birth or at a young age, the immune system
initially does not react to the hepatitis B virus. This phase of the infection
is known as the immune tolerant phase. Despite high levels of virus in the body,
there may be little evidence of inflammation and no symptoms. This phase
typically lasts for years, even up to two or three decades. It is important to
know that the immune tolerant phase is generally not seen in individuals who
become infected during adulthood.
Immune clearance phase
During the third to fourth decade of chronic hepatitis B
acquired in childhood, the immune system may start to react to the virus. This
is known as the immune clearance phase. In contrast, an infection acquired in
adulthood usually begins with the immune clearance phase. In the immune
clearance phase, the immune system attacks the hepatitis B virus-infected liver
cells in an attempt to clear the virus. This causes inflammation, liver injury,
and the development of scar tissue. Standard liver blood tests are abnormal, and
the liver biopsy shows inflammation and/or formation of scar tissue (fibrosis).
The severity of liver cell destruction, the degree of fibrosis, and the duration of
the immune clearance phase determine the outcome of chronic hepatitis B. The
more severe the destruction and fibrosis and the longer the phase, the more
likely it is that cirrhosis will develop.
Quiescent phase
Following the immune clearance phase, the viral infection may enter a less
active phase known as the quiescent phase. During this phase, there are no
symptoms, the levels of hepatitis B virus become very low, and the standard
liver blood tests become normal or nearly normal. Advanced scaring or cirrhosis
that may have developed earlier, however, remains. Occasionally, during the
quiescent phase, the virus becomes active again. This is known as a "flare," and
often is associated with symptoms, abnormal liver blood tests, and further
injury to the liver. The flares are caused by reactivation of the immune system
against the virus. Flares can be very severe and result in further scarring of
the liver. The disease in many of these individuals will progress to cirrhosis
and eventually to advanced or end-stage cirrhosis with its associated
complications, including liver cancer.
Infected individuals who experience a mild immune clearance phase and move
into the quiescent phase are known as healthy carriers of hepatitis B virus.
These individuals usually have normal liver tests and do not have symptoms;
however, they can still transmit the hepatitis B viral infection to others. The
risk of hepatitis B virus carriers developing cirrhosis and liver cell cancer is
small although the risk is higher as compared to people without chronic
hepatitis B.
Next: What medications are used to treat hepatitis B? »
- interferon - Describes the medication interferon (Roferon-A, Intron-A, Rebetron, Alferon-N, Peg-Intron, Avonex, Betaseron, Infergen, Actimmune, Pegasys), a drug used in managing many diseases that involve the immune system.
- Liver Blood Tests - Learn about liver blood tests used to detect liver damage disease such as fatty liver, cirrhosis, hepatitis, Tylenol liver damage, and more. This includes measuring the aminotransferases enzymes (AST and ALT levels)
- Liver Cancer - Get information on liver cancer, its symptoms, causes, diagnosis, staging, prognosis, treatment, and prevention.
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