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What
is Hepatitis B? > Glossary
Glossary
Acute Hepatitis Infection: A new, suddenly
occurring infection. It occurs with a person’s first
exposure to the hepatitis B virus.
Adefovir dipivoxil (Hepsera): An oral nucleoside
analogue drug that interferes with the replication of the hepatitis
B virus (e.g. it can slow down or stop the virus from reproducing).
It was approved for chronic hepatitis B in September 2002.
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. Antibodies can be produced in response
to a vaccine or to a natural infection. They circulate in the
blood to protect against future infections.
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.
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.
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 hepatitis C viruses are bloodborne pathogens since they
are spread through blood and can cause a liver infection.
Carcinoma: A new growth or malignant
tumor that can occur throughout the body (e.g. hepatocellular
carcinoma refers to liver cancer).
Centers for Disease Control and Prevention (CDC): This
federal organization is concerned with the prevention and control
of communicable diseases such as hepatitis B and C. It conducts
extensive research and provides information about public health
topics.
Chronic Hepatitis B Infection: A patient
who tests positive for the hepatitis B virus for more than
6 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.
Complications: New medical problems
that arise while treating existing ones.
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 a burst 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.
Entecavir: An oral nucloeside analogue drug
that interferes with the replication of the hepatitis B virus
(e.g. it can slow down or stop the virus from reproducing).
It was the third oral drug approved for chronic hepatitis B
in April 2005.
Enzymes: Naturally occurring chemical
substances in the human body that help a chemical reaction
take place.
Epidemiology: A field of medical science
that studies the incidence, distribution, and control of disease
in a population. This information is often used to determine
causes and methods of controlling diseases.
False-Positive: A test result that
mistakenly gives a positive reading.
Fatty Liver: Refers to a condition where
fat accumulates in liver cells. This accumulation of fat does
not generally cause liver damage, but it needs to be monitored.
It is detected by liver biopsy.
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.
Food and Drug Administration (FDA): A federal
organization charged with protecting the public health. It
establishes safety and effectiveness guidelines for healthcare
products such as the drugs that are used to treat hepatitis
B and C.
Gastroenterology: The field of medicine
that focuses on the function and disorders of the GI system,
which includes the esophagus, stomach, pancreas, intestines,
and liver.
Genome: Refers to the genetic material
of an organism such as a human or a virus.
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:
Hepatitis A: Formerly called “infectious
hepatitis”, it is caused by the hepatitis A virus (HAV)
and is an acute infection. There is no chronic infection. Most
patients recover completely within 6 to 10 weeks. Hepatitis
A is spread mainly via feces and contaminated food and water.
There is a safe vaccine for HAV.
Hepatitis B: Formerly called “serum
hepatitis”, it is caused by the hepatitis B virus (HBV). Approximately
10% of infected adults progress to chronic hepatitis B; 90%
of newborns born to HBV infected women develop chronic infections;
and young children have a 30-50% chance of developing a chronic
infection. It is spread primarily through blood, unprotected
sex, shared needles, and from an infected mother to her newborn
during the delivery process. There is a safe vaccine for HBV.
Hepatitis C: Formerly known as “non-A,
non-B hepatitis”, it is caused by the hepatitis C virus
(HCV). Approximately 85% of infected adults will develop
chronic hepatitis C infections. It is spread through infected
blood, primarily in those who use illicit street drugs and
those who received blood transfusions prior to1992 (the first
year that a blood test for HCV became available for screening
the blood supply). There is no vaccine.
Hepatitis D: Known as “delta hepatitis”,
it is caused by the hepatitis D virus (HDV). This virus can
only co-infect patients who are already infected with hepatitis
B. Hepatitis D infection is rare in the United States. It occurs
primarily in recipients of multiple blood transfusions, including
patients with hemophilia or those undergoing renal dialysis,
and among people who share contaminated needles. There is no
vaccine.
Hepatitis E: Also referred to as “enterically
transmitted non-A, non-B hepatitis”, it is caused by
the hepatitis E virus (HEV). It is spread through fecal contamination
of water; occurs primarily in developing countries; and is
found rarely in the United States. Hepatitis E infection results
in an acute infection much like hepatitis A; it does not cause
chronic infection. There is no vaccine.
Hepatitis F: Only a handful of cases have
been reported from France with subsequent experimental transmission
to primates. The virology, epidemiology and clinical importance
of the hepatitis F virus are uncertain. There is no commercial
test nor is there a vaccine.
Hepatitis G: The hepatitis G virus (also
called hepatitis GB virus or HGBV-C) is a distant relative
of the hepatitis C virus. It appears to be transmitted through
transfusions (one to two percent of US blood donors have HGV
RNA detectable in their serum). Its role in acute and chronic
hepatitis remains unclear. Recent studies suggest that the
virus may not even replicate in the liver. At the present time,
HGV does not appear to be an important cause of clinical liver
disease. There is no commercial test nor is there a vaccine.
Hepatitis B Blood Panel: There are
three common hepatitis B tests that make up the Hepatitis B
Blood Panel. This is a simple test that requires only one blood
sample, which can be obtained during an office visit to the
doctor.
1. 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.
2. 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.
3. 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.
HBeAg: A marker of a high degree of HBV infectivity,
it correlates with a high level of HBV replication. It is primarily
used to help determine the clinical management of patients
with chronic HBV 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 needlestick, 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 correlates well with infectivity. It is used to assess
and monitor the treatment of patients with chronic HBV infection.
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.
Immune System: The body’s defense
system against invasion by foreign bodies such as bacteria,
viruses, fungi, parasites, and malignant cells.
Immunology: The branch of medicine
that studies the immune system, immunity, and allergies.
Infection: The results of the presence
of harmful microorganisms in the body. Infections can be acute
(sudden) or chronic (persistent).
Injection: A method of administering
drugs or nutrients into the body using a needle.
- Intramuscular (IM): into muscle
tissue.
- Intravenous (IV): into a vein.
- Subcutaneous (SQ): beneath the skin.
Interferon: A protein that is produced by
the body to protect against infection. Many different cells
including liver cells produce natural interferon. Interferon
also can be manufactured artificially through biotechnology
for the treatment of chronic hepatitis B and C.
Interferon Alpha-2b (Intron A): A drug that
mimics naturally occurring “interferon”, which
is an infection-fighting immune substance produced by the body.
It is self-administered at least three times a week by injection.
This was the first drug approved for chronic hepatitis B in
1991. Available for both adults and children greater than 2
years old.
Investigational Drug: A new drug that
is undergoing clinical trials to prove its effectiveness and
safety (see clinical trials).
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.
Lamivudine (Epivir-HBV, Zeffix, Heptodin): An
oral nucleoside analogue drug that interferes with the replication
of the hepatitis B virus (e.g. it can slow down or stop the
virus from reproducing). It was the second drug approved for
chronic hepatitis B in December 1998. Available for both adults
and children.
Liver: The largest glandular organ
in the body. The liver has many functions that include, but
are not limited to the production of protein and cholesterol,
the production of bile and clotting factors, the storage of
sugar in the form of glycogen, and the breakdown of carbohydrates,
fats, and proteins. The liver also breaks down and excretes
many medications.
Liver Biopsy: The removal of a small
piece of tissue from the liver using a special needle. The
tissue is examined under a microscope to look for the presence
of inflammation or liver damage (see histology).
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 (ALT): 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.
Needlestick: Refers to an accidental
puncture of the skin while handling hypodermic needles or syringes.
This is most common among health care providers such as physicians,
nurses, and emergency response personnel.
Non-Responders: Patients who do not
respond to therapy or a vaccine within a specific period.
Patient Compliance: Patients who correctly
follow all the instructions about a course of therapy as directed
by their physician are considered to be “compliant” with
a treatment protocol (see protocol below).
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.
Peg Interferon Alfa-2a (Pegasys): A pegylated
interferon drug that mimics naturally occurring “interferon”,
which is an infection-fighting immune substance produced by
the body. It is self-administered once a week by injection
and seems to have fewer side effects than the interferon alpha.
Approved for treatment of chronic hepatitis B in May 2005.
Percutaneous: Passage or absorption
of substances into the body through unbroken skin.
Perinatal Transmission (vertical transmission): Transmission
of an infectious disease, such as hepatitis B, from mother
to newborn. All pregnant women should be tested for hepatitis
B since newborns have a 90% chance of becoming chronically
infected if they do not receive the first dose of hepatitis
B vaccine and a single dose of HBIG within 12 hours after delivery.
The infant will also need additional doses of hepatitis B vaccine
at one and six months of age to ensure a complete immune response.
Persistent: A disease or other medical
condition that returns or continues over a long time.
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.
Post-Transfusion Hepatitis: Liver inflammation,
or hepatitis, that occurs when the body reacts unfavorably
to a blood transfusion. This is now rare in the United States
due to careful blood screening procedures.
Protein: A substance made of a string
of amino acids. Proteins are the “building blocks” of
the human body.
Protocol: A detailed plan of a scientific
experiment or medical treatment. A specific step-by-step procedure
is used in clinical trials to test new drugs and treatments
for diseases such as chronic hepatitis B.
Recombinant DNA: Genetic material that
has been altered and recombined in the laboratory by cutting
up DNA molecules and splicing together specific DNA fragments.
Many drugs, including the hepatitis B vaccines, are produced
using recombinant DNA methods.
Reconstitution: The process of adding
liquid to a dry powder to make a new solution. Prescription
drugs that are given by injection are often provided as a dry
powder, which must be reconstituted (e.g. liquid must be added)
before it can be used.
Recreational Drugs (illicit drug use): Illegal
drugs, such as marijuana, crack, cocaine, and heroin. People
who use these drugs have a much greater risk of acquiring a
hepatitis B or C infection as a result of sharing needles or
engaging in other behaviors that increase their risk of exposure
to infected blood.
Relapse: The return (or recurrence)
of symptoms of a disease after a period of improvement.
Remission: A period of time during
which all or some of the symptoms of a disease have disappeared
or decreased in severity. Remission may occur spontaneously
or as a result of medical treatment.
Retreatment: Treatment that is restarted
after a patient has suffered a relapse or has not responded
to treatment the first time.
Risk Factors: Refers to behaviors and
conditions that increase the possibility of an individual developing
a disease. Smoking is a risk factor for lung cancer. Jobs that
expose a person to blood or the use of illegal drugs are risk
factors for acquiring a hepatitis B or C infection.
Screening: Testing blood samples or
blood donations for the presence of disease. Before blood donations
are accepted, they are screened for hepatitis B, hepatitis
C, and HIV/AIDS and other bloodborne pathogens.
Self-Administration: Therapy, such
as interferon injections, that patients give to themselves
rather than having it done by a health care provider.
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.
Serology: Refers to the study of serum
(the clear portion of a body fluid) for its antibody content.
When a person is exposed to a microorganism, such as the hepatitis
B or C virus, the body produces specific antibodies against
it. In laboratory testing, the antibodies react with antigens
in specific ways that can be used to confirm the identity of
the microorganism, however, this test is not used to diagnose
a current infection.
Spleen: An organ located in the left
upper abdomen that removes old red blood cell and other blood
cells from circulation. The spleen can enlarge in a person
who has cirrhosis.
STD (sexually transmitted disease): A
disease that is transmitted through sexual contact.
Sustained Response: A response to therapy
that continues over a long time period. For example,
a patient treated for chronic hepatitis B or C who remains
free of the virus for at least 6 months after stopping treatment
is considered to have a sustained response to therapy.
Symptom: Any change in the body or
its functions, as perceived by the patient, which could indicate
the presence of disease.
T-Cells: A type of white blood cells
that are involved in rejecting foreign tissue, regulating immunity,
and controlling the production of antibodies to fight infection.
Therapy: Treatment of a disease.
Transaminases: Refers to SGOT or SGPT,
which are older terms for the ALT and AST amino transferases
(see liver function tests).
Transfusion: The introduction of whole
blood or components of blood (such as plasma, platelets) from
one person to another.
Transmission: The way or method by which
a disease can be spread.
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.
Variceal Bleeding: Abnormal bleeding
from ruptured blood vessels in the esophagus that results from
severely impaired blood flow through the liver. Patients with
advanced cirrhosis are at greatest risk for this complication.
This is a life-threatening emergency and requires immediate
medical attention.
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.
Viremia: Refers to the presence or
amount of a given virus in the bloodstream.
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.
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Taber’s
Medical Dictionary