When a physician suspects that a patient might have inflammation of the liver or some other form of liver disease or damage, one of the very first things that he does is order blood work to determine whether the liver enzymes are elevated. With this information he can get a better understanding of what is going on, and what course of action needs to be taken. The enzymes that the blood test is looking for are ALT and AST, or amino transaminase and aspartate transaminase. Their presence in the bloodstream is an indication of some kind of damage in the liver, as these enzymes are generally not found in the blood, or if they are they are usually in very low levels.
Symptoms
Liver enzymes are often found to be elevated in the course of doing regular blood work, but sometimes your doctor will order them because you are displaying symptoms of liver damage. These symptoms would include fatigue, loss of appetite, jaundice and swelling of your legs and feet. If you are displaying any of these symptoms, or if your blood work unexpectedly comes back elevated, your doctor will probably order more tests to try to determine the exact cause. In many cases the enzymes can be elevated for benign reasons, including having received an injection or physical injury of some kind, or taking specific medications which can temporarily raise the enzyme level.
In other cases the proteins are present in your blood stream as a result of inflammation or damage to the liver caused by drinking too much alcohol, eating too much fatty food, Hepatitis A, B, or C, heart failure or obesity. It can also be caused by a number of other illnesses or conditions, including celiac disease, heart failure, mononucleosis and pancreatitis. Diagnostic tests including MRI, CT scans, and ultrasounds
can help to determine the exact root of the problem.
Blood Work
Both ALT and AST are generally found in very small quantities in the blood stream; they are normally only found in high numbers within the liver itself. The numbers that you can expect in a normal liver enzyme analysis would find the ALT numbers ranging from five to forty units per liter, and AST would be expected to fall within a range of seven to fifty six units per liter.
When blood work comes back with liver enzyme numbers above this range, there is automatically concern about the possibility of liver damage, though this is not always the cause of elevated liver enzymes. Similarly, even if they do indicate liver inflammation or lesions, or even cirrhosis, the numbers do not always reflect the level of damage; you cannot interpret a high number as meaning something worse than a lower number.
Most importantly, when liver enzymes are found to be outside the normal range, it is an indication that more testing needs to be done with an eye to gauging the actual functioning of the liver. These tests can include a coagulation panel, a platelet count and a bilirubin count.
If any of these tests also come back either too high or too low, it becomes much clearer that there is liver damage that needs to be addressed. These problems can range from a diagnosis of fatty liver disease, to the consumption of too much alcohol, to hepatitis. There are also genetic causes for liver disease, as well as the introduction of foreign substances such as acetaminophen and other medications that are toxic for the liver.