Liver function tests check the levels of certain enzymes and proteins in your blood. Levels that are higher or lower than normal can indicate liver problems.
http://www.mayoclinic.org/tests-procedures/liver-function-tests/basics/why-its-done/PRC-20012602
Liver blood tests are some of the most commonly performed blood tests. These tests can be used to assess liver functions or liver injury. An initial step in detecting liver damage is a simple blood test to determine the level of certain liver enzymes (proteins) in the blood. Under normal circumstances, these enzymes mostly reside within the cells of the liver. But when the liver is injured for any reason, these enzymes are spilled into the blood stream.
http://www.medicinenet.com/liver_blood_tests/article.htm
AST and ALT are considered to be two of the most important tests to detect liver injury, although ALT is more specific to the liver than is AST. Sometimes AST is compared directly to ALT and an AST/ALT ratio is calculated.
https://labtestsonline.org/understanding/analytes/alt/tab/test
ALT is often performed together with a test for AST or as part of a liver panel. For more about ALT results in relation to other liver tests, see the Liver Panel article.
https://labtestsonline.org/understanding/analytes/alt/tab/test
Normally, levels of ALT in the blood are low. Very high levels of ALT (more than 10 times normal) are usually due to acute hepatitis, sometimes due to a viral infection. In acute hepatitis, ALT levels usually stay high for about 1-2 months but can take as long as 3-6 months to return to normal.
https://labtestsonline.org/understanding/analytes/alt/tab/test
Liver function tests are blood tests used to help diagnose and monitor liver disease or damage. The tests measure the levels of certain enzymes and proteins in your blood. Some of these tests measure how well the liver is performing its normal functions of producing protein and clearing bilirubin, a blood waste product. Other liver function tests measure enzymes that liver cells release in response to damage or disease. Abnormal liver function test results don't always indicate liver disease. Your doctor will explain your results and what they mean. 1  Why it's done.
http://www.mayoclinic.org/tests-procedures/liver-function-tests/basics/definition/PRC-20012602
A health practitioner usually orders an ALT test (and several others) to evaluate a person who has signs and symptoms of a liver disorder. Some of these may include: 1  Weakness, fatigue. 2  Loss of appetite. 3  Nausea, vomiting. 4  Abdominal swelling and/or pain. 5  Jaundice. 6  Dark urine, light-colored stool. 7  Itching (pruritus).
https://labtestsonline.org/understanding/analytes/alt/tab/test
If the liver is injured or damaged, the liver cells spill these enzymes into the blood, raising the AST and ALT enzyme blood levels and signaling liver disease. Other blood tests pertaining to the liver are measurements of some of the other enzymes found the liver.
http://www.medicinenet.com/liver_blood_tests/article.htm
The alanine aminotransferase (ALT) test is typically used to detect liver injury. It is often ordered in conjunction with aspartate aminotransferase (AST) or as part of a liver panel to screen for and/or help diagnose liver disease.
https://labtestsonline.org/understanding/analytes/alt/tab/test
Liver function tests can be used to: 1  Screen for liver infections, such as hepatitis. 2  Monitor the progression of a disease, such as viral or alcoholic hepatitis, and determine how well a treatment is working. 3  Measure the severity of a disease, particularly scarring of the liver (cirrhosis). 4  Monitor possible side effects of medications.
http://www.mayoclinic.org/tests-procedures/liver-function-tests/basics/why-its-done/PRC-20012602
what does a alt test check for
An ALT test check to detect liver injury. A alt test check is done to detect liver injury. The Alanine Aminotransferase Test checks in to detect liver injury. Alanine Transaminase test checks for liver injury. The Alanine Aminotransferase Test checks for a liver injury. An ALT test is used to check liver injury.