What are the most common liver function tests?
 
Liver function tests are used to measure specific enzymes and proteins in your blood. Depending on the test, either higher- or lower-than-normal levels of these enzymes or proteins can indicate a problem with your liver.
Some common liver function tests include:
 
Alanine transaminase (ALT) test
 
Alanine transaminase (ALT) is used by your body to metabolize protein. If the liver is damaged or not functioning properly, ALT is released into the blood. This causes ALT levels to increase. A high result on this test can be a sign of liver damage. The normal range for ALT is 7–55 units per liter (U/L), according to the Mayo Clinic. Low ALT is not indicative of any health issues.
 
Aspartate aminotransferase (AST) test
 
Aspartate aminotransferase (AST) is an enzyme found in several parts of your body, including the heart, liver, and muscles. Since AST levels aren’t specific for liver damage, it’s usually measured together with ALT to check for liver problems. Your doctor may use an ALT-to-AST ratio to help with their diagnosis. When the liver is damaged, AST is released into the bloodstream. A high result on an AST test might indicate a problem with the liver or muscles. The normal range for AST is 8–48 U/L. Low AST is not indicative of any health issues.
 
Alkaline phosphatase (ALP) test
 
Alkaline phosphatase (ALP) is an enzyme found in your bones, bile ducts, and liver. An ALP test is typically ordered in combination with several other tests. High levels of ALP may indicate liver damage, blockage of the bile ducts, or a bone disease.
 
Children and adolescents may have elevated levels of ALP because their bones are growing. Pregnancy can also raise ALP levels. The normal range for ALP is 45–115 U/L.
 
Low levels of ALP can occur following a blood transfusion or heart bypass surgery. Low ALP can also result from a variety of conditions, including zinc deficiency, malnutrition, and Wilson disease.
 
Albumin test
 
Albumin is the main protein made by your liver. It performs many important bodily functions. For example, albumin:
stops fluid from leaking out of your blood vessels
nourishes your tissues
transports hormones, vitamins, and other substances throughout your body
An albumin test measures how well your liver is making this particular protein. A low result on this test indicates that your liver isn’t functioning properly. The normal range for albumin is 3.5–5.0 grams per deciliter (g/dL).
 
Bilirubin test
 
Bilirubin is a waste product from breakdown of red blood cells. It’s ordinarily processed by the liver. It passes through the liver before being excreted through your stool.
 
A damaged liver can’t properly process bilirubin. This leads to an abnormally high level of bilirubin in the blood. A high result on the bilirubin test indicates that the liver isn’t functioning properly. The normal range for bilirubin is 0.1–1.2 milligrams per deciliter (mg/dL).
 
Why do I need a liver function test?
 
Liver tests can help determine if your liver is working correctly. The liver performs a number of vital bodily functions, such as:
removing contaminants from your blood
converting nutrients from the foods you eat
storing minerals and vitamins
regulating blood clotting
producing proteins, enzymes, and bile
making factors that fight infection
removing bacteria from your blood
processing substances that could harm your body
maintaining hormone balances
 
What are the symptoms of a liver disorder?
 
Symptoms of a liver disorder include:
weakness
fatigue or loss of energy
weight loss
jaundice (yellow skin and eyes)
symptoms of nephritic syndrome (swelling around the eyes, belly, and legs)
discolored bodily discharge (dark urine or light stools)
nausea
vomiting
diarrhea
abdominal pain