Liver Function Test

Liver Function Test, Enzymes, and Risk Involved, Range Chart

The liver function test is blood tests to help diagnose and monitor liver disease or injury. The purpose of these tests is to measures the levels of certain enzymes and proteins in the blood.

Some of these tests measure the performance of the liver in its normal functions of producing protein and destroying bilirubin, a product of blood waste. Other liver function tests measure enzymes that release liver cells in response to damage or disease.

Results from abnormal liver function tests do not always indicate liver disease. The doctor will definitely explain the results and what they mean.

Why this test is performed?

The Liver function test is done for :

  • Track liver infections like hepatitis.
  • Monitor the progression of a disease, such as viral or alcoholic hepatitis, and determine how the treatment is working.
  • Measure the severity of a disease, especially liver (cirrhosis) scars monitor the possible side effects of medicines.

Liver function tests detect the levels of certain enzymes and proteins in the blood. Levels above or below normal may indicate liver problems. 

Some common liver function tests include:

Alanine Transaminase (ALT): ALT is an enzyme found in the liver that helps to convert proteins into energy for liver cells. When the liver becomes impaired, ALT is released into the bloodstream, and the level increases.

Aspartate transaminase (AST): This enzyme helps in amino acid metabolism. In healthy conditions, ALT is present at a low level but an increase in the level of this enzyme may indicate liver damage, disease, or muscle damage.

Alkaline phosphatase (ALP)  ALP is an enzyme found in the liver and bones and is important for breaking down proteins. High-to-normal levels of ALP can indicate liver damage or diseases, such as bile duct block or some bone disease.

Albumin and total protein: Albumin is one of several proteins produced in the liver. The body needs these proteins to fight infection and perform other functions. Below normal levels of albumin and total protein may indicate liver injury or disease.

Bilirubin: This is an enzyme produced during the normal breakdown of red blood cells. After the breaking down of red blood cells, bilirubin passes through the liver and is excreted in the feces. Elevated levels of bilirubin (jaundice) can indicate injury or liver disease or some types of anemia.

Gamma-Glutamyltransferase (GGT): GGT is a blood enzyme. Higher than normal levels may indicate damage to the liver or bile duct.

L-lactate dehydrogenase (LD): An enzyme found in the liver and increased levels may indicate liver damage but may be elevated in many other disorders.

Prothrombin time (PT): PT is the time it takes for your blood to clot. Increased PT can indicate liver damage, but it can also be elevated if you are taking some blood-thinning medications, such as warfarin.

Any risk involved in this test?

Blood samples for liver function tests are usually taken from the vein of the hand. The main risk associated with blood tests is pain or injury at the blood collection site. Most people have no severe reaction to blood collection.

What do you expect during and after the test?

During the Test

The blood sample for liver function tests is usually collected through a small needle inserted into a vein in the arms fold. The needle attaches to a small tube to collect blood. You may experience intense pain when the needle is inserted into your hand and some short-term discomfort at the site after the needle is removed.

After testing

After drawing of blood, the blood sample will be sent to a laboratory for analysis. If laboratory analysis is done on-site, you can give the test results within hours. If the doctor sends blood samples to an external laboratory, the results can be got after a few days.

Common blood test results range for common liver tests include:

ALT 7 to 55 units per liter (U / L)
AST 8 to 48 U / L
ALP 40 to 129 U / L
Albumin 3.5 to 5.0 grams per dl (g / dL)
Total Protein 6.3 to 7.9 g / dL
Bilirubin 0.1 to 1.2 mg per deciliter (mg /dL)
GGT 8 to 61 U / L
LD 122 to 222 U / L
PT 9.4 to 12.5 seconds

These results range are typical for adult males. General results vary from laboratory to laboratory and may vary slightly for women and children.

Your doctor will use these results to help diagnose your condition or may prescribe the treatment you need. If you already have liver disease, liver function tests can help determine how the disease is progressing and whether you are responding to treatment.

(Disclaimer: Information provided in this piece of article is purely for educational purposes only. All results must be clinically correlated with the patient’s data to make an accurate diagnosis.) 



References :
  1. Medplus Medical Encyclopedia: US National Library of Medicine; Liver Function Test.
  2. National Health Call Centre Network: Healthdirect Australia (Internet); Council of Australian Government; Liver Functions Test 
  3. American Liver Foundation ( Internet). New York (NY): American Association for the Study of Liver Disease; LiverFunction Test


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