hepatitis B infection and appropriate measures to
limit exposure to hepatitis C. People who already
have chronic hepatitis, cirrhosis, or other condi-
tions that increase the risk for liver cancer, the herb
MILK THISTLE(silymarin) may help protect the liver
from further damage. Other preventive measures
include avoiding circumstances associated with
liver cancer, notably excessive alcohol consump-
tion. Though the number of people who develop
primary liver cancer is rising, it remains less com-
mon than metastatic (secondary) liver cancer.
See also CANCER PREVENTION; CANCER TREATMENT
OPTIONS AND DECISIONS; CELL STRUCTURE AND FUNCTION;
ENVIRONMENTAL HAZARD EXPOSURE; HEAVY-METAL POI-
SONING; HEPATITIS PREVENTION; METASTASIS; OCCUPA-
TIONAL HEALTH AND SAFETY; SURGERY BENEFIT AND RISK
ASSESSMENT.
liver disease of alcoholism Permanent damage
to the LIVERthat results from long-term, excessive
ALCOHOLconsumption. Alcohol is one of the most
toxic substances ingested into the body. It enters
the bloodstream unchanged, about 20 percent
absorbed from the STOMACHand 80 percent from
the SMALL INTESTINE. The liver must filter alcohol
from the blood, a process that certain enzymes in
the liver regulate. The enzymes limit the amount
of alcohol the liver can extract, allowing alcohol to
accumulate in the bloodstream.
The first of these enzymes, alcohol dehydroge-
nase (ADH), converts the alcohol into acetalde-
hyde. Acetaldehyde gives the breath of a person
who has been drinking alcohol its characteristic
odor. It is also a toxin, available as an industrial
chemical for numerous manufacturing uses such
as a solvent, hardener, and preservative. The sec-
ond of these enzymes, aldehyde dehydrogenase,
facilitates acetaldehyde’s break down into acetic
acid (the same acid found in vinegar) and acetyl-
coenzyme A. These substances are less toxic than
acetaldehyde. Though aldehyde dehydrogenase
works rapidly, it cannot convert all of the alde-
hyde before this toxic chemical causes the deaths
of hepatocytes. Other enzymes in the liver further
metabolize the acetic acid and acetate into GLUCOSE
(energy) and carbon dioxide (waste).
With repeated exposure to acetaldehyde, struc-
tural changes take place in the liver. The first of
these is the accumulation of fat in the liver. The
liver must direct nearly its full efforts to metabo-
lize alcohol, in the effort to protect itself from the
alcohol’s toxic effects. As a consequence other
metabolic functions in the liver slow, altering car-
bohydrate and lipid (fat) METABOLISM. The liver can
metabolize alcohol at the rate of about 15 grams
per hour, a pace that results in minimal hepato-
cytic damage. Alcohol consumption that exceeds
this rate (equivalent to 1 ounce of 100-proof dis-
tilled spirits, one 12-ounce beer, or 4 ounces of
wine) maintains alcohol circulation in the blood-
stream until the liver can accommodate its metab-
olism. Repeated excessive alcohol consumption
characteristically results in three liver disorders,
which may exist singly or collectively.
Alcoholic hepatitis The HEPATITISof ALCOHOLISM,
also called Laennec’s hepatitis, occurs when the
repeated irritation of alcohol results in INFLAMMA-
TION of the liver. When the flow of alcohol
through the liver stops, symptoms abate and
hepatocytes (the primary working cells of the
liver) regenerate. Within a few months of alcohol
cessation, the liver can restore itself to a normal
level of function.
Alcoholic steatohepatitis Acetylcoenzyme A,
one of the products of alcohol metabolism, inter-
feres with the liver’s synthesis and storage of fatty
acids such that fatty tissue accumulates in the
liver. Alcoholic STEATOHEPATITISimproves when the
liver’s metabolism of alcohol stops, and liver struc-
ture can return to normal with alcohol cessation.
Alcoholic cirrhosis Alcoholic CIRRHOSISis a con-
dition in which repeated INFLAMMATION(hepatitis)
causes SCARtissue to form and replace hepato-
cytes. As is the case with cirrhosis resulting from
any cause, damage that has already occurred to
the liver is not reversible. However, alcohol cessa-
tion halts the progression of cirrhosis to limit fur-
ther damage.Symptoms and Diagnostic Path
The symptoms of alcoholic liver disease are much
the same as those of nonalcoholic liver disease and
includeJAUNDICE (yellowish discoloration of the
SKIN), right upper ABDOMINAL PAIN, ASCITES (fluid
accumulation in the abdominal cavity), NAUSEA,
loss of APPETITE, and FATIGUE. The diagnostic path
begins with LIVER FUNCTION TESTSand a thorough
assessment of drinking habits. Additional diagnos-liver disease of alcoholism 71