Liver Function Tests, also referred to as hepatic panel or liver panel, is a set of diagnostic assays which evaluate the functioning of the liver to determine if the hepatic tissues are healthy or afflicted by any disease. It entails measuring the concentrations of key liver enzymes and proteins in the blood. These include assessing levels of gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), aspartate transaminase (AST), alanine transaminase (ALT), lactate dehydrogenase (LD), albumin, total protein, bilirubin and prothrombin time (PT).

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Liver function test

The Liver And Its Functions:

The liver is a key internal organ, bearing a reddish-brown colour with a wedge-like irregular shape and a weight of around 1.5 kg, which performs many vital functions in the body. These comprise detoxifying impurities in blood, aiding in the metabolism of nutrients in food, assimilating any medicines, drugs, storing vitamins, minerals for use by the system when needed, as well as ensuring proper blood clotting processes. The liver synthesizes a substance known as bile, which is stored in the gall bladder and helps in lipid metabolism and the break down of fats. Infections in the liver or failure of the organ to function results in severe ailments like jaundice, hepatitis, cirrhosis, sometimes even leading to liver failure and hampering the overall health of the system.

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The liver function tests are thus essential to identify any problems arising in the liver and diagnose, treat them promptly, besides evaluating the normal operations of the hepatic tissues. Moreover, it is necessary to gain insight into the types of liver function tests, the procedure involved and what the results of the diagnostic assay imply for liver wellness and all-round wellbeing.

Types Of Liver Functions Tests:

Based on which enzyme or protein is being evaluated, liver function tests consist of different types of assays:

Gamma Glutamyl Transferase (GGT):

This is an enzyme found in blood and used by the liver to process nutrients in food.

Alkaline Phosphatase (ALP):

This is a key enzyme present in the liver and bones, that plays a role in the breakdown of proteins.

Aspartate Transaminase (AST):

This enzyme in the liver digests amino acids for optimal metabolism in the body.

Alanine Transaminase (ALT):

This enzyme in the liver is involved in the conversion of proteins to the energy required for biochemical reactions in the hepatic cells.

Lactate Dehydrogenase (LD):

This is another distinct enzyme that is found in liver cells.

Albumin And Total Protein:

Albumin is a vital protein synthesized in the liver, along with many other proteins, to build strong immunity in the system to combat diseases and infections.


This is a substance formed during the normal processing of red blood cells, which is absorbed by the liver and excreted via stools.

Prothrombin Time (PT):

Prothrombin is a pivotal protein in coagulation processes and the prothrombin time assay measures the time taken for blood to clot in the body.

How Is It Done?

The procedure of liver function tests is similar to any other blood test. The doctor, nurse or certified pathologist collects a sample of blood from the patient. The process typically involves clearing out a patch of skin on the arm to prevent contamination, applying pressure to view the veins clearly and injecting a sterile needle to extract blood. After this, the area on the skin is covered with a bandage to avert any infection.

The liver function tests comprising giving a blood sample usually do not pose any risks in the patient. Only in rare instances, the person feels dizzy, faint due to loss of blood, or experiences a headache with minor pain, soreness at the site of injection.

Why Is It Done?

The liver function tests are performed to study the normal functioning of the hepatic tissues in a healthy person. This assay also helps detect cases of liver disorders like hepatitis infection, jaundice and any side effects of medications on the liver.

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When symptoms of pain in the lower abdomen, yellowing of skin, eyes, itching in the skin, loss of appetite and fatigue with dark coloured stools are observed in an individual, it is advised to promptly take the liver function tests. This assists in detecting any illness prevailing in the liver and assuring proper medical treatment of the affected person.

Significance Of Results:

For GGT, the normal range is 0 – 51 IU/litre and higher levels indicate problems in the bile duct and hepatic cells.

ALT levels are ideally below 25 IU/litre and higher levels indicate defects in liver cells.

AST levels up to 40 IU/litre are normal and higher values signify liver complications.

ALP levels are up to 120 IU/litre and higher than normal amounts signify inflammation in the liver or obstruction in bile ducts.

Albumin levels in healthy people are between 3.4 – 5.4 g/dL of blood, while total protein is in the range of 6 – 8.3 g/dL and volumes below this range signify liver damage.

Total bilirubin levels are between 0.3 – 1.9 mg/dL and high levels above this range could be due to liver disease or anaemic conditions.

Ideal PT times are 10 to 14 seconds and if blood takes longer to clot, then in indicates issues with coagulation processes or internal bleeding.


Liver function tests are a valuable diagnostic assay to determine the normal functioning of the hepatic cells in the body as well as to detect any disease or infection in the organ. However, the liver function tests are not conclusive in determining liver damage or failure and additional tests of CT scans, liver biopsies need to be performed to confirm instances of damage, infection or defects in the liver.