Contributed by- Dr. Pooja Chaudhary
The liver helps in breaking down the food, cleaning the blood, making proteins, and storing energy. But our faulty dietary habits, hectic lifestyle, disturbed biological clock and a family history of liver ailments puts us on the susceptible side.
If things go wrong with the liver, a person might show a number of symptoms. These can vary from a yellow tint of the skin to slurred speech. Hence, it is very important to keep our liver healthy. This can be done by getting our liver checked regularly, through liver function tests.
Liver Function Test (LFT)
Liver function tests are the blood tests which can help in diagnosing and monitoring liver damage or disease. The tests measure the levels of certain enzymes and proteins present in our blood.
LFT helps in measuring how well the liver is performing its normal functions of producing protein and clearing bilirubin (blood waste product), measuring enzymes that liver cells release in response to damage or disease. What is important to note is that all abnormal liver function test results don’t always indicate a liver disease.
When is Liver Function Test required?
Liver function tests are performed to:
- Screen for liver infections, such as hepatitis
- Monitor the progression of disease such as viral or alcoholic hepatitis, and determine how well a treatment is working
- Keep a check on the possible side effects of medications
- Measure the severity of a disease, mostly scarring of the liver (cirrhosis)
Liver Function tests are also advised when:
- A patient has a history of heavy drinker or is alcoholic
- Family history of liver disease
- Overweight, especially if a person is suffering from diabetes or high blood pressure
Levels high or low than normal can indicate liver problems.
Panel of tests included in Liver Function Test
Liver function test includes a panel of tests. Following are the various forms of liver test and the liver function test results explained:
Function in Liver
|Alanine Transaminase Test (ALT)||It is an enzyme that helps in breaking down the proteins and is mostly found in the liver.|
|Alkaline Phosphatase Test (APT)||It is an enzyme present in the liver, bile ducts & bone.|
|Albumin & Total Protein Test||The liver makes two proteins, albumin and globulin. Our body needs these proteins to fight infections and to perform other functions.|
|Aspartate Transaminase Test (AST)||It is an enzyme that helps in metabolizing the alanine, an amino acid.|
|Bilirubin||It is a substance produced during the normal breakdown of red blood cells. Bilirubin passes through the liver and is excreted in the stool.|
|Gamma-glutamyltransferase (GGT)||It is an enzyme present in the blood.|
|L-lactate dehydrogenase (LD)||It is an enzyme found in the liver.|
|Prothrombin time (PT)||It is the time taken by the blood to clot.|
Liver Function Test Range
Listed here are the liver function test normal range and liver function test interpretations
|AST||0 to 45 U/L||It is elevated in heart and muscle disease. A very high level is frequently seen with acute hepatitis.|
|ALT||0 to 45 U/L||Higher levels are indicative of acute hepatitis.|
|ALP||30 to 120 U/L||It can be significantly increased with obstructed bile ducts, cirrhosis, liver cancer, and also with bone disease.|
|GGT||0-45U/L||It is often elevated in those who consume alcohol or other liver-toxic substances to excess. It is used as liver function test for alcohol.|
|Total Bilirubin|| 0 to 20 U/L
|An elevated level indicates Jaundice.|
|LD||140 U/L to 280 U/L||This is elevated with very acute liver disease or liver tumours.|
|PT||11 to 14 sec||A prolonged or increased PT can be seen with liver disease, vitamin K deficiency, and use of drugs to reduce the risk of clotting (warfarin), and with coagulation factor deficiencies.
|Total Protein||60 to 80 g/L||It is mostly normal with liver disease.|
Why all or some of the enzymes becomes elevated in case of liver disease?
Usually, these enzymes are confined inside the liver cells and they only leak into the blood stream when the liver cells get damaged. Thus, measuring these liver enzymes is only able to detect liver damage and does not measure liver function in a highly sensitive way.
How is the test done?
The test is a basic blood draw test that does not require fasting. The patient might feel a pinch or a sting when the needle is pricked. Reports can be made available within 24 hours of sample collection.