Health A-Z

Medical Content Created by the Faculty of the Harvard Medical School


What Is It?

No body organ performs a wider variety of essential jobs than the liver. It:

  • Produces essential proteins that help blood to clot

  • Removes or neutralizes poisons, drugs and alcohol

  • Manufactures bile that helps the body to absorb fats and cholesterol

  • Helps to maintain normal blood sugar levels

  • Regulates several hormones

Cirrhosis is a disease in which normal liver cells are replaced by scar tissue, which interferes with all of these important functions. In extreme cases, the damage is so severe that the only solution is a liver transplant.

Cirrhosis has many causes. In the United States and Europe, the most common causes are excessive alcohol use and chronic infection with the hepatitis C virus.

Alcohol has a toxic effect on liver cells. Alcoholic cirrhosis tends to develop after a decade or more of heavy drinking, although it is possible for "social drinkers" to have cirrhosis. It is not known why some people are more prone to adverse reactions than others, but women are at greater risk of cirrhosis, even when they drink less alcohol than men.

Chronic hepatitis C causes inflammation of the liver that eventually can lead to cirrhosis. Without treatment, about one out of every five people with chronic hepatitis C develops cirrhosis after 20 years.

Chronic hepatitis B, which causes damage in a similar way, is another common cause of cirrhosis in the world. But it is less common in industrialized countries because of routine vaccination against hepatitis B.

More recently, non-alcoholic fatty liver disease has become a more common cause of cirrhosis. Doctors call it nonalcoholic steatohepatitis (NASH). Fat deposition in the liver leads to inflammation, which can progress to scarring.

Rarer causes of cirrhosis include:

  • Autoimmune diseases that attack the bile ducts or liver cells

  • Severe reactions to prescription drugs

  • Prolonged exposure to environmental toxins

  • Infections from bacteria and parasites usually found in the tropics or Asia

  • Repeated episodes of heart failure with liver congestion.

  • Certain inherited diseases, including:

    • Hemochromatosis, in which too much iron builds up in the liver and other organs

    • Wilson's disease, which produces abnormal concentrations of copper

    • Alpha-1-antitrypsin deficiency, which is the absence of a particular enzyme in the liver

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From Health A-Z, Harvard Health Publications. Copyright 2007 by the President and Fellows of Harvard College. All rights reserved. Written permission is required to reproduce, in any manner, in whole or in part, the material contained herein. To make a reprint request, contact Harvard Health Publications. Used with permission of StayWell.

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