Proteins are tiny specialized structures used by the cells and the body for many functions. They can be strong and provide structural support, or form channels through which chemicals can flow through, for example. A specific type of protein is an enzyme. An enzyme increases the rates of chemical reactions. All the organs perform chemical reactions with the help of enzymes. The liver has many enzymes. Problems in the liver can damage liver cells and release their enzymes into the blood, which can be measured as an indicator of liver cell damage.
Diagnosis of Elevated Liver enzymes
According to "Harrison's Principles of Internal Medicine" by Dr. Anthony Fauci, the liver enzymes typically tested for in the blood include aspartate aminotransferase or AST, alkaline aminotransferase or ALT, alkaline phosphatase or ALK Phos, and gamma-glutamyl transpeptidase or GGT. AST and ALT are released from damage to the functional liver cells. ALK Phos is released more from damage to the bile ducts, but can also be found in other tissues, and GGT tends to be released more from damage to bile ducts. The amount of liver enzymes in the blood parallels the amount of damage to the liver. Generally the level of ALT is higher or about the same as AST. If AST is significantly higher, that is more indicative of damage from alcohol.
Acute Liver Enzyme Elevation
Acute liver enzyme elevation is generally from some sudden strong damage to the liver. "According to Harrison's Principles of Internal Medicine" by Anthony S Fauci M.D. this can be from toxins such as high doses of Tylenol or mixing Tylenol with alcohol. Infections can directly damage the liver. Alternatively, a systemic infection throughout the body can cause the blood pressure to drop very low, depriving the liver of blood and causing damage that releases enzymes. A heart attack can do the same if the heart is unable to supply blood to the liver. Trauma such as a car collision can also damage the liver and release enzymes.
Chronic Liver Enzyme Elevation
Chronic liver enzyme elevation is from ongoing disease processes. Alcoholic liver disease is one common cause of chronic liver disease. Viral hepatitis is another cause. Inherited diseases, drugs and immune system dysfunction also can cause ongoing damage that chronically elevates the liver enzymes.
Symptoms from Elevated Liver Enzymes and Liver Damage
Elevated liver enzymes themselves do not cause symptoms, rather they are a sign of liver damage useful for diagnosis of disease and tracking its progression. Liver damage can be without symptoms. As the liver damage progresses, the liver will be less able to filter the blood. As a result toxins such as ammonia can build up and cause confusion and fatigue. Drug doses will need to be modified because the liver is not available to process the drugs. The liver will not make proteins, disrupting immune system function, causing increased fluid buildup and swelling in the body and increasing the tendency to bruise and bleed. Nutrition needs will change, as the body will not process proteins as efficiently, and carbohydrates are not stored in the liver.
References
- "Harrison's Principles of Internal Medicine"; Anthony S Fauci et al; 17th Ed 2008
- "Robbins and Cotran Pathologic Basis of Disease"; Vinay Kumar et al; 8th Ed 2009
