Hepatitis (plural
hepatitides) implies inflammation of the
liver characterized by the presence of
inflammatory cells in the
tissue of the organ. The name is from
ancient Greek hepar (ἧπαρ), the root being
hepat- (ἡπατ-), meaning
liver, and suffix
-itis, meaning "inflammation" (c. 1727). The condition can be self-limiting, healing on its own, or can progress to scarring of the liver. Hepatitis is
acute when it lasts less than six months and chronic when it persists longer. A group of
viruses known as the hepatitis viruses cause most cases of liver damage worldwide. Hepatitis can also be due to toxins (notably
alcohol), other infections or from
autoimmune process. It may run a
subclinical course when the affected person may not feel ill. The patient becomes unwell and symptomatic when the disease impairs liver functions that include, among other things, removal of harmful substances, regulation of blood composition, and production of bile to help digestion.
Causes
Acute
Chronic
Symptoms
Acute
Clinically, the course of acute hepatitis varies widely from mild symptoms requiring no treatment to
fulminant hepatic failure needing
liver transplantation. Acute viral hepatitis is more likely to be asymptomatic in younger people. Symptomatic individuals may present after convalescent stage of 7 to 10 days, with the total illness lasting 2 to 6 weeks.
[ V.G. Bain and M. Ma, Acute Viral Hepatitis, Chapter 14, ]Initial features are of nonspecific flu-like symptoms, common to almost all acute
viral infections and may include
malaise,
muscle and
joint aches,
fever,
nausea or
vomiting,
diarrhea, and
headache. More specific
symptoms, which can be present in acute hepatitis from any cause, are: profound
loss of appetite,
aversion to
smoking among
smokers,
dark urine,
yellowing of the
eyes and
skin (i.e.,
jaundice) and
abdominal discomfort. Physical findings are usually minimal, apart from
jaundice (33%) and tender
hepatomegaly (10%). There can be occasional
lymphadenopathy (5%) or
splenomegaly (5%).
Chronic
Majority of patients will remain asymptomatic or mildly symptomatic, abnormal
blood tests being the only manifestation. Features may be related to the extent of liver damage or the cause of hepatitis. Many experience return of symptoms related to acute hepatitis. Jaundice can be a late feature and may indicate extensive damage. Other features include abdominal fullness from enlarged
liver or
spleen, low grade
fever and
fluid retention (
ascites). Extensive damage and scarring of liver (i.e.,
cirrhosis) leads to weight loss, easy bruising and bleeding tendencies.
Acne, abnormal
menstruation,
lung scarring, inflammation of the
thyroid gland and
kidneys may be present in
women with
autoimmune hepatitis.
Findings on clinical examination are usually those of
cirrhosis or are related to
etiology.
Types
Viral
Most cases of acute hepatitis are due to viral infections:
Other viral causes
Other viral infections can cause hepatitis (inflammation of the liver):
Alcoholic hepatitis
Ethanol, mostly in
alcoholic beverages, is a significant cause of hepatitis. Usually
alcoholic hepatitis comes after a period of increased
alcohol consumption. Alcoholic hepatitis is characterized by a variable constellation of symptoms, which may include feeling unwell, enlargement of the liver, development of fluid in the
abdomen ascites, and modest elevation of liver blood tests. Alcoholic hepatitis can vary from mild with only liver test elevation to severe liver inflammation with development of jaundice, prolonged
prothrombin time, and
liver failure. Severe cases are characterized by either
obtundation (dulled consciousness) or the combination of elevated
bilirubin levels and prolonged
prothrombin time; the mortality rate in both categories is 50% within 30 days of onset.
Alcoholic hepatitis is distinct from
cirrhosis caused by long term alcohol consumption. Alcoholic hepatitis can occur in patients with chronic
alcoholic liver disease and alcoholic cirrhosis. Alcoholic hepatitis by itself does not lead to cirrhosis, but cirrhosis is more common in patients with long term alcohol consumption. Patients who drink alcohol to excess are also more often than others found to have hepatitis C. The combination of hepatitis C and alcohol consumption accelerates the development of cirrhosis.
Drug induced
A large number of drugs can cause hepatitis:
The clinical course of drug-induced hepatitis is quite variable, depending on the drug and the patient's tendency to react to the drug. For example,
halothane hepatitis can range from mild to fatal as can
INH-induced hepatitis.
Hormonal contraception can cause structural changes in the liver.
Amiodarone hepatitis can be untreatable since the long
half life of the drug (up to 60 days) means that there is no effective way to stop exposure to the drug.
Statins can cause elevations of
liver function blood tests normally without indicating an underlying hepatitis. Lastly, human variability is such that any drug can be a cause of hepatitis.
Other toxins
Other
Toxins can cause hepatitis:
- White phosphorus, an industrial toxin and war chemical.
Metabolic disorders
Some metabolic disorders cause different forms of hepatitis.
Hemochromatosis (due to
iron accumulation) and
Wilson's disease (
copper accumulation) can cause liver inflammation and
necrosis.
Non-alcoholic steatohepatitis (NASH) is effectively a consequence of
metabolic syndrome.
Obstructive
"Obstructive jaundice" is the term used to describe jaundice due to obstruction of the
bile duct (by
gallstones or external obstruction by
cancer). If longstanding, it leads to destruction and inflammation of liver tissue.
Autoimmune
Anomalous presentation of
human leukocyte antigen (HLA) class II on the surface of
hepatocytes, possibly due to
genetic predisposition or acute liver infection; causes a cell-mediated
immune response against the body's own liver, resulting in
autoimmune hepatitis.
Alpha 1-antitrypsin deficiency
In severe cases of
alpha 1-antitrypsin deficiency (A1AD), the accumulated
protein in the
endoplasmic reticulum causes
liver cell damage and
inflammation.
Non-alcoholic fatty liver disease
Non-alcoholic fatty liver disease (NAFLD) is the occurrence of
fatty liver in people who have no history of alcohol use. It is most commonly associated with
obesity (80% of all obese people have fatty liver). It is more common in women. Severe NAFLD leads to inflammation, a state referred to as
non-alcoholic steatohepatitis (NASH), which on biopsy of the liver resembles alcoholic hepatitis (with fat droplets and
inflammatory cells, but usually no
Mallory bodies).
The diagnosis depends on
medical history,
physical exam,
blood tests,
radiological imaging and sometimes a
liver biopsy. The initial evaluation to identify the presence of fatty infiltration of the liver is
medical imaging, including such
ultrasound,
computed tomography (CT), or
magnetic resonance (MRI). However, imaging cannot readily identify inflammation in the liver. Therefore, the differentiation between steatosis and NASH often requires a liver biopsy. It can also be difficult to distinguish NASH from
alcoholic hepatitis when the patient has a history of alcohol consumption. Sometimes in such cases a trial of abstinence from alcohol along with follow-up blood tests and a repeated liver biopsy are required.
NASH is becoming recognized as the most important cause of liver disease second only to hepatitis C in numbers of patients going on to
cirrhosis.
Ischemic hepatitis
Ischemic hepatitis is caused by decreased circulation to the liver cells. Usually this is due to decreased blood pressure (or
shock), leading to the equivalent term "shock liver".
Patients with
ischemic hepatitis are usually very ill due to the underlying cause of
shock. Rarely,
ischemic hepatitis can be caused by local problems with the
blood vessels that supply
oxygen to the liver (such as
thrombosis, or
clotting of the
hepatic artery which partially supplies
blood to
liver cells).
Blood testing of a person with
ischemic hepatitis will show very high levels of
transaminase enzymes (
AST and
ALT), which may exceed 1000 U/L. The elevation in these
blood tests is usually transient (lasting 7 to 10 days). It is rare that
liver function will be affected by
ischemic hepatitis.
See also
