You might have always heard your general practitioner (GP) saying how the liver is the vital organ without which your body can't process food, store energy, or get rid of toxins. Therefore, any malfunction or disease involving the liver can have medical implications. 

But how can you know whether your liver is functioning optimally? It's when your GP might recommend getting a liver function test (LFT). The LFTs involve taking the patient's small blood sample to check liver's health by measuring the organ proteins and enzyme levels. 

Let's uncover a liver function test, why you need to undergo LFT, and what tests it entails.

What are the Liver Function Tests? 

Liver function tests (LFTs), also known as liver panel or liver chemistries, are the blood tests used to monitor the patient's liver health. GPs and specialists assess the state of your liver with LFTs by measuring the levels of liver enzymes, proteins, and bilirubin in your blood. 

Depending on the liver function test results, higher or lower levels of these enzymes, proteins, and byproducts than typical levels can indicate a problem with your liver. 

What do You Need to Get a Liver Function Test?

Many liver function tests are part of the common test named a comprehensive metabolic panel (CMP). Healthcare providers often recommend patients get a CMP for their routine body checkups to monitor liver and other organ-related diseases. 

You might also need to visit the medical facility for a liver function test because of the following symptoms of liver disease or damage:

• Lack of appetite
• Weakness
• Nausea and vomiting
• Swelling in ankles and legs
• Jaundice 
• Frequent itching 
• Fatigue
• Swelling or pain in the abdomen
• Light-coloured stool or dark-coloured urine

Regardless of whether you have these symptoms, your doctor might ask you to get your liver tested if you are at a high risk for liver damage. The risk might be high if:

• You have a family history of liver disease, like fatty liver disease.
• You have alcohol use disorder (AUD).
• You already suffer from liver disease, LFT can help keep tabs on the disease and how well a specific treatment is working.
• You suffer from certain medical conditions, like diabetes, anaemia, high blood pressure, and high triglycerides.
• Have gallbladder disease
• Have been taking certain medicines that can have side effects on your liver, such as tuberculosis drugs, statins, antiseizure medication, or antibiotics.
• Have hepatitis, such as hepatitis B or hepatitis C or exposed to the virus that can cause hepatitis.

What are the Primary Liver Function Tests?

The primary tests that a liver function panel includes are the following: 

• Alanine transaminase (ALT) test

Alanine transaminase (ALT) is an enzyme in your liver that metabolises protein by converting it into energy for liver cells. When your liver gets damaged or doesn't function appropriately, alanine transaminase can be released into the bloodstream, increasing ALT levels. 

If your ALT test shows higher alanine transaminase levels than usual, it can indicate liver damage. 

• Alkaline phosphatase (ALP) test

Alkaline phosphatase (ALP) is the enzyme in the human body's liver, bones, and bile ducts that breaks down proteins. A healthcare professional prescribes an Alkaline phosphatase (ALP) test to evaluate the liver's bile duct system. 

If the test indicates higher levels of ALP than usual, it means your liver might be damaged or you suffer from the disease, like biliary obstruction or specific bone problems. 

• Aspartate transaminase (AST) test

Aspartate transaminase (AST) is an enzyme in multiple body parts, including the brain, heart, liver, muscles, and pancreas. Its function is to help your body break down vital amino acids. 

If your liver is damaged or functions improperly, AST gets released into the bloodstream. Aspartate transaminase (AST) test showing higher levels of AST than typical might indicate a problem with your liver or muscles. 

• Bilirubin test 

Bilirubin is a waste product formed in your body from the breakdown of RBCs red blood cells). The liver is normally responsible for processing bilirubin, and it's eliminated from your body through the stool. 

If your bilirubin test shows a higher level of bilirubin than usual, your liver might be damaged enough to not properly process this waste product. Sometimes, certain conditions like anaemia or liver duct blockage can also boost the bilirubin levels in your body.

• Albumin test

Albumin is among many proteins made in an individual's liver to fight against infections and perform other bodily functions. An albumin test measures how well your liver is making albumin reflecting synthetic function of liver. Lower levels than usual might indicate liver disease or damage. 

• Gamma-glutamyl transferase (GGT) test

Gamma-glutamyl transferase (GGT) is an enzyme that's found in the blood. Your GGT test showing the higher-than-usual levels of gamma-glutamyl transferase might indicate liver or bile duct damage. It is also increased in patients who have significant alcohol intake.

• Prothrombin time (PT) test

Prothrombin time (PT) is the time your blood takes to clot. PT test results showing increased prothrombin time might indicate liver damage. Along with albumin, PT is also considered as a measures of liver synthetic function.

Summing up it all!

A liver function test (LFT) is quintessential for you if you have any symptoms related to liver disease or damage. Moreover, if you have a family history of liver disease or are alcoholic or diabetic, getting LFTs regularly can aid in monitoring the progression of liver disease. 

Once you undergo a liver function test, your healthcare provider can help interpret the results. If you are a potential candidate for liver disease or damage, they might prescribe other tests and appropriate treatment.