Detox & Digest: Your Busy Liver

Proteins are critical building blocks of all cells, essential for body growth, development, and health. They are the basic components of enzymes, many hormones, antibodies and clotting agents and form the structural framework of most organs. Proteins also act as transport vehicles, ferrying vitamins, minerals, lipids and other materials to various parts of the body.

Proteins found in the blood can be grouped into two categories: globulins and albumin. There are hundreds of different types of globulins, many of which, such as antibodies, play important roles in the immune system. Albumin, however, is the most abundant protein in plasma. One of its main jobs is to help balance the osmotic pressure of the blood and tissue, which basically maintains the right levels of water.

Liver function is typically evaluated by a panel of tests that help doctors distinguish between the many different possible causes of liver damage, which can range from alcohol abuse to hepatitis infection or the side effects of certain medications.

One of the tests in the liver panel measures total protein in the serum (serum is plasma minus clotting agents). If total protein is abnormal, further tests can identify the specific proteins that are abnormally low or high. Albumin levels are tested as well as levels for two enzymes that are found in cells throughout the body, but mostly in the heart and liver. Two of these enzymes, ALT (or alanine aminotransferase), and AST, (aspartate transaminase) leak out of cells into the bloodstream when the liver is damaged. A blood test for these biomarkers, as well other tests in the liver panel, can in this way detect liver damage before more obvious symptoms, like jaundice, appear. LESS

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The most common cause of cirrhosis worldwide is probably infection with the hepatitis B virus, though this is not the case in the U.S. and Europe. Alcoholic liver disease and infection with the hepatitis C virus are two other major causes. Liver damage also results from severe reactions to prescription medicines (such as statins), over-the-counter drugs (such as acetaminophen, especially in combination with alcohol abuse), and exposure to environmental toxins or parasites.

There are an estimated 1.5 million carriers of hepatitis B in the U.S., with 750,000 affected by chronic hepatitis B; there are an estimated 2 to 5 million carriers of hepatitis C; and almost 4 million Americans have antibodies indicating prior exposure to hepatitis A. More than 2 million Americans are affected by alcoholic liver disease. [numbers need check]

Many people have more than one cause of liver damage. Obesity and diabetes are increasingly becoming common causes of liver disease, especially in combination with alcohol, hepatitis C, or both. Considering the alarming rise in the incidence of obesity and diabetes, we may see the incidence of liver disease follow these trends.

Liver disease often develops because of chronic alcohol consumption, but it can also occur without alcohol, in a form referred to as non-alcoholic fatty liver disease. If fat constitutes more than 10% of the liver, it is considered fatty. Initially, it may not cause problems, but can lead to inflammation and scarring.

Cirrhosis is scarring of the liver due to injury or disease. And though cirrhosis can have many causes, the most common causes in the U.S. are chronic alcoholism and hepatitis. Scarring of the liver is irreversible, but treating the cause (or, in the case of alcoholism, eliminating alcohol) can keep it from getting worse.

Alcoholic liver disease is usually closely tied to the number of years and amounts of alcohol that have been consumed, though not all heavy drinkers will develop it; genetics and gender also play roles. About 5 percent of people with cirrhosis get liver cancer. Hepatitis is the other major risk factor for developing cancer that begins in the liver. LESS

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The ancient Greeks thought the four humours, blood, phlegm, yellow bile, and black bile, controlled both bodies and temperament, and for 2,000 years an excess of black bile was thought to make people melancholic, and an excess of yellow bile to make them choleric (cranky and cantankerous).

And excess bile can indeed cause problems. When red blood cells are broken down, bilirubin, a yellow pigment and component of hemoglobin, is normally eliminated as bile; when bilirubin is not efficiently eliminated because of liver disease, the result is jaundice, a yellowing of the skin and whites of the eyes. Bile ducts can be also blocked by gallstones, tumors, or inflammation, which can cause bile and other wastes to accumulate in the liver. Symptoms include jaundice, dark brown urine, pale-colored stools, as well as fever and sharp pain if the duct from the gallbladder is blocked. LESS

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