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Fatty Liver (Steatosis) Your Liver Lets You Live Your liver, located under your right rib cage, normally weighs about three pounds and is the body's second largest organ. (Your skin is the largest.) It is a complex chemical factory which produces many important substances such as bile, digestive enzymes, clotting factors, cholesterol, and proteins. It is essential in the metabolism of fats, carbohydrates, proteins, and the various vitamins and minerals. It helps control the level of blood sugar and fats. It cleanses the blood and detoxifies drugs and potentially harmful chemicals such as alcohol. The liver is a storehouse for blood, vitamins and minerals, and glycogen - the stored form of sugar - the body's major fuel. The liver is an amazing machine and largely unappreciated - until something goes wrong. What is a fatty liver?
Almost all the organs of the body contain some fat. That is not necessarily a bad thing. Fat cells provide insulation, protection, and are an efficient way to store extra energy. After a typical meal, dietary fat is absorbed by the intestines and enters the blood stream which carries the fat directly to the liver. Normally, this fat is metabolized in the liver and converted to energy. If the amount of fat delivered is excessive, it is stored in the liver and other tissues. The normal liver contains about 5% fat. The rest of the liver is made up of liver cells called hepatocytes which do all the work of the liver. When the amount of fat in the liver exceeds 10%, healthy liver cells are replaced by fat cells. This condition is termed a fatty liver, or steatosis. Recent surveys have shown fatty liver to be much more common than previously recognized. It now affects about 23% of adult Americans and has become the most common cause of abnormal liver blood tests in the US population. Who gets it? The typical patient is an older obese woman who may be diabetic, but fatty liver affects both sexes and may occur in those of normal weight. It is also quite common in those who consume excessive amounts of alcohol. Is it serious?
It can be. There are two basic categories of fatty liver - that seen in alcoholics and that which occurs in non-drinkers. It has been recognized for centuries that chronic alcoholism can cause progressive liver failure. The first stage of alcoholic liver disease is a fatty liver. At this stage, the damage is often reversible if the individual becomes totally abstinent. But, with continued drinking, the outcome is dismal. Liver cells die and are replaced by scar tissue. When excessive scar tissue develops (cirrhosis), the liver fails. So, a fatty liver in an alcoholic who keeps drinking is quite serious. Until recently, it was believed that in non-alcoholics a fatty liver was just a curiosity - a consequence of being overweight or a diabetic. New scientific studies have identified non-alcoholic fatty liver as a separate disease entity also with potentially serious consequences. It is now believed that 10-20% of non-drinkers who have a fatty liver will also go on to develop liver cirrhosis. Why this happens is not known. Fatty liver has become the most common cause of cirrhosis in non-drinkers. NASH (Non-alcoholic steatohepatitis) In 1980, scientists noted changes on liver biopsies in non-alcoholics that looked very much like the liver damage seen in chronic alcoholics who continue to drink. In addition to excess fat, there were signs of dying liver cells (necrosis), and inflammation. They termed this condition non-alcoholic steatohepatitis, commonly referred to as NASH. (The phrase "steato" simply means fat and "hepatitis" means liver inflammation.) The presence of dying liver cells and inflammation makes NASH a more severe form of fatty liver. Patients with NASH are one step closer to developing liver cirrhosis. The progression is:
2. fatty liver (steatosis) 3. inflammation, cell death (steatohepatitis, NASH) 4. scar tissue (fibrosis) 5. excessive scar tissue and liver failure (cirrhosis)
As mentioned above, the main cause is deposition of excessive fat within the liver. There are many reasons why this might happen including:
2. Non-Alcoholic Fatty Liver There is no evidence that heredity plays a significant role in this disease. It is not passed from parent to child. What are the symptoms of a fatty liver? A person with a fatty liver is not necessarily ill. In fact, the most common symptom is no symptom at all. Fat accumulation is a gradual process that occurs silently over many years. Eventually, the liver becomes enlarged and may cause a vague discomfort in the right upper abdomen. Rarely, there may be complaints of nausea. How is it diagnosed? The typical scenario is a patient who has routine blood tests performed for another reason and is told that the "liver enzyme" reading is unexpectedly elevated. Perhaps they tried to donate blood and were rejected. It may have been an insurance physical or just a routine checkup. The most common abnormality in the blood tests is two to three-fold elevation in liver enzymes called SGOT and SGPT. In non-alcoholic fatty liver other liver blood tests are usually normal, particularly GGTP and MCV which are often elevated in alcoholics. In any case, these individuals are usually referred to a specialist to investigate the underlying cause. If there is a history of chronic alcohol abuse, the underlying cause is usually obvious. In non-drinkers, investigation usually focuses on searching for other potential causes such as viral hepatitis, hemochromatosis (iron oveload), gallstones, cancer, or fatty liver. Non-alcoholic fatty liver is suspected in any adult who has unexplained elevated liver blood tests and drinks no more than 2 alcoholic drinks daily. To investigate further, more blood tests are usually required. Imaging studies such as a sonogram or CT scan are helpful in ruling out cancer and gallstones. They can also help determine if the liver contains excessive fat. If NASH is suspected or the diagnosis unclear, a needle liver biopsy is often performed. This test allows the doctor to obtain a small piece of liver tissue to examine directly under the microscope. Here are two liver biopsies as seen under the microscope. The one on the left is normal. The one on the right shows an excessive amount of fat cells which appears as pale open circles. How is a fatty liver treated? At present, there is no proven therapy to reverse a fatty liver directly. Therefore, treatment is usually directed at the underlying cause. Alcohol must be stopped completely. Potentially offending medications may need to be changed, if possible. Uncontrolled diabetes must be better controlled. High blood fats need to be reduced. Excessive weight must be lost through a diet and exercise program. A high protein very low carbohydrate diet (Atkins diet) is sometimes recommended, but, as yet, not supported by any scientific literature. Several reports suggest that the use of ursodeoxycholic acid (URSO), a natural bile salt, can be helpful. How can I avoid a fatty liver? Do not drink excess alcohol. If you drink, do not exceed 2 drinks per day on a regular basis. Maintain a proper body weight. Eat a healthy diet - overeating and extreme dieting can result in a fatty liver. Diabetes and high blood fats should be aggressively treated. Conclusion Fatty liver is a common silent process that can occur both in drinkers and in non-drinkers. It should be suspected if liver blood tests are unexpectedly elevated, especially in those that are alcoholics, obese, diabetic, or have high blood fats. Most cases are silent, but some individuals may go on to develop cirrhosis and liver failure. Alcoholism accelerates the process. Non-drinkers usually have a dormant course, but nearly half with NASH develop progressive fibrosis, and as many as one-sixth develop cirrhosis. As yet, there is no specific treatment so therapy is directed to the underlying cause.
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