The liver removes toxic chemicals from the blood. When the liver is damaged from disease or injury, the cells of the liver are unable to function properly. They become unable to remove byproducts of metabolism such as ammonia resulting from protein digestion. High amounts of ammonium ion in the blood affects the brain with a range of symptoms from mild confusion to possible brain damage and death. Medical treatment along with a diet low in protein can help.
Bacteria living in the digestive tract break down proteins for absorption into the body used to repair cells. Protein breaks down into nitrogen compounds including ammonia in the intestine. According to the World Health Organization, the intestine produces 4,000mg of ammonia per day. The bloodstream absorbs this ammonia and takes it first to the liver for processing through chemical reactions. Ammonia is turned into urea and released from the body in the urine. If the liver is damaged and the cells can't remove ammonia from the blood, the ammonia stays in the blood and enters general circulation resulting in toxicity.
Function of the Liver
The liver located on the right side of the body at the base of the ribcage has four lobes. Blood from all parts of the body passes through the liver for detoxification and metabolism before entering or returning to general circulation. Nutrients absorbed from food by digestion travel in the blood to the liver before being transported to the heart to enter general circulation to take nutrients throughout the body. Liver cells detoxify the blood and metabolize chemicals for use by the target organs.
Causes of Liver Damage
Damage to the liver cells resulting in reduced function of the liver may be caused by injury, by exposure to chemicals such as alcohol and drugs. Damage can also be the result of an inherited disease, infections caused by viruses, cancer, shock and heart failure. Scar tissue from cirrhosis means loss of cell function.
Symptoms of Liver Damage
When the liver cells can't remove toxic chemicals from the blood, some people experience no symptoms, while others complain of severe general itching, swelling of the abdomen or legs and altered mental states of not wanting to do anything, confusion or stupor. Liver damage causes jaundice, the yellowing of the skin and the whites of the eyes. For appropriate diagnosis, a physician takes a complete medical history, performs a physical examination and orders blood tests to determine liver function.
Ammonia Levels in the Body
Chemical reactions in the body release ammonia as a waste product and the liver turns it into a less toxic chemical called urea. The kidneys remove the urea from the body in the urine. According to the National Institutes of Health, the normal range of ammonia in the blood is between 15 and 45mcg/dL. Abnormal cell function in the liver means ammonia levels increase in the blood.
High amounts of ammonia affect the brain resulting in confusion, brain damage, coma and can cause death. Early symptoms of ammonia toxicity related to decreasing liver function include inability to concentrate, sleepiness and being prone to irritability. Physicians diagnose ammonia toxicity and use two medicines to lower ammonia levels. The antibiotic neomycin acts in the colon to kill the bacteria that break down proteins and the sugar lactulose reduces the absorption of nitrogen from the intestines.
Limiting the amount of protein from meats, nuts and other protein sources in the diet lowers the potential for ammonia toxicity. Protein cannot be removed from the diet because the body needs the amino acids absorbed from protein to repair cells. The National Institutes of Health recommends 1gm of protein for each kilogram of body weight; however, a physician working with a dietitian will determine the appropriate amount on an individual basis. In addition, reduce salt intake to prevent bloating that may cause swelling in the liver.
- National Institutes of Health; MedlinePlus Article; Ammonium Ion
- National Institutes of Health; MedlinePlus Article; Diet - liver disease
- "The Liver Disorders and Hepatitis Sourcebook"; Worman, Howard J MD; 2006
- World Health Organization; Environmental Health Criteria No. 54; Ammonia; 1986