Cirrhosis - Causes

Causes

Several processes can lead to cirrhosis.

Alcoholism

Alcoholism particularly endangers the liver. Alcoholic cirrhosis (also sometimes referred to as portal, Laennec's, nutritional, or micronodular cirrhosis) is the primary cause of cirrhosis in the U.S. It is estimated to be responsible for 44% of deaths from cirrhosis in North America. Some experts believe this estimate is low. One Canadian study found alcohol to be the major contributor to 80% of all cirrhosis deaths.

The relationship between alcohol and cirrhosis is generally as follows:

• Alcohol is absorbed from the small intestine, and the blood carries it directly into the liver, where it becomes the preferred energy source.
• In the liver, alcohol converts to toxic chemicals, such as acetaldehyde (AcH), which trigger the production of powerful immune factors called cytokines. These molecules in large amounts can cause inflammation and tissue injury and are proving to be major culprits in the destructive process in the liver. AcH is particularly being researched because it plays a role in most actions of alcohol, including damaging effects on the liver that may lead to cirrhosis.
• The injured liver eventually is unable to breakdown fatty acids, compounds that make up fat. Over time, then, fat accumulates, further impairing the liver's ability to absorb oxygen and increasing its susceptibility to injury. During the initial phase, the fat-laden liver becomes greatly enlarged, but it eventually shrinks as cirrhosis develops.

Chronic Hepatitis

Chronic hepatitis, either hepatitis B or hepatitis C, is the second leading cause of cirrhosis. Chronic hepatitis C is the more dangerous form and accounts for one-third of all cirrhosis cases. About 5 - 20% of patients with chronic hepatitis C, and 5 – 10% of patients with chronic hepatitis B, eventually develop cirrhosis over the course of several decades. The longer a patient has had chronic hepatitis, the greater the risk for eventually developing cirrhosis. A 2005 study indicated that cirrhosis develops in 70% of patients who have had hepatitis C for more than 60 years.

The hepatitis virus can produce inflammation in liver cells, resulting in their injury or destruction. If the condition is severe enough, the cell damage becomes progressive, builidng a layer of scar tissue over the liver. In advanced cases, as with alcoholic cirrhosis, the liver shrivels in size, a condition called postnecrotic or posthepatic cirrhosis.