The liver plays a central role in maintaining the body’s metabolic balance. It processes nutrients, filters toxins from the blood, helps in digestion, and produces essential proteins for blood clotting and other functions. When the liver isn’t working properly, it may not show obvious symptoms at first. That’s where liver function tests (LFTs) become crucial—they offer a window into how well the liver is performing and whether there's any damage or disease affecting it.

Liver function tests are a group of blood tests used to assess the liver’s health and functionality. These tests measure the levels of liver enzymes, proteins, and bilirubin in the blood, helping healthcare providers detect inflammation, infection, injury, or disease. Understanding how these tests work, their purpose, normal ranges, and how to interpret the results can empower patients to make informed decisions about their health.

Purpose of the Liver Function Test

Liver function tests are conducted for various medical reasons, often to evaluate and monitor the health of your liver. Your healthcare provider may recommend these tests if you:

• Exhibit symptoms of liver disease, such as jaundice (yellowing of the skin or eyes), dark-colored urine, abdominal pain, or persistent fatigue.
• Have a history of significant alcohol consumption or substance use that could potentially harm the liver.
• Are using medications that might affect liver function and need evaluation for possible side effects.
• Have a chronic liver condition such as hepatitis B, hepatitis C, or nonalcoholic fatty liver disease (NAFLD).
• Require regular monitoring to manage an existing liver condition and track its progression or response to treatment.
• Are preparing for surgery or undergoing treatments that could impact liver health.

How to Prepare for a Liver Function Test?

Preparing for a liver function test (LFT) is usually simple and straightforward. Here are some important points to keep in mind:

• Fasting: You may need to fast for 8–12 hours before the test. This means no food or drinks except water. This is especially important if your LFT is combined with other tests like cholesterol or glucose panels. Always follow the specific instructions from your healthcare provider.
• Medications and Supplements: Make sure to inform your doctor about all the medications, vitamins, herbal remedies, or supplements you are currently using. These can sometimes affect liver enzyme levels and impact the accuracy of your test results.
• Alcohol Intake: Avoid consuming alcohol before your test, as it can interfere with the accuracy of your results.

By keeping these steps in mind, you’ll ensure accurate results and help your healthcare provider get a clear picture of your liver health. 

Procedure for Liver Function Test

The procedure for a liver function test is straightforward:

• Blood Sample Collection: A healthcare worker will clean the skin on your arm, usually near your elbow, and insert a needle into a vein to collect a small amount of blood. You might feel a tiny pinch during this step.
• Testing in the Lab: The blood sample is sent to a lab, where experts check for enzymes, proteins, and other substances related to liver health.
• Getting Results: Depending on the facility, results are ready within a few hours or a couple of days.

After the test, you can go back to your regular activities immediately. You may feel a little soreness or notice minor bruising where the needle went in, but this usually goes away quickly.

Liver Function Test: Results Interpretation

Liver function tests typically measure the following:

• Albumin: A protein produced by the liver that plays a key role in maintaining fluid balance in the body.
• Total Protein: This test evaluates the total amount of proteins in your blood, including albumin and globulins, which are primarily synthesised in the liver.
• Enzymes (ALP, ALT, AST, GGT): These enzymes are crucial for various chemical reactions in the body and are predominantly generated by the liver. Alkaline phosphatase (ALP), alanine transaminase (ALT), aspartate aminotransferase (AST), and gamma-glutamyl transferase (GGT) fall under this category.
• Bilirubin: A waste product formed when old red blood cells are broken down. The liver processes and removes most of the bilirubin from the body.
• Lactate Dehydrogenase (LDH): Found in many tissues throughout the body, this enzyme is present in significant amounts in the liver.
  Prothrombin Time (PT): Measures the time taken for blood to clot, relying on prothrombin, a protein produced by the liver that is essential for blood clotting.

Liver Function Test Normal Ranges

Liver function tests (LFTs) measure various enzymes, proteins, and substances in the blood to assess liver health. Here’s an overview of the liver function test normal range chart, summarising the standard values for key components of LFTs:

These ranges may vary slightly depending on the laboratory and testing methods used. 

Abnormal Liver Function Test Results

Abnormal liver function test results can happen for many reasons, including:

• Hepatitis (A, B, or C): Infections that damage the liver.
• Alcoholic Liver Disease: Liver damage caused by excessive alcohol use.
• Nonalcoholic Fatty Liver Disease (NAFLD): Fat buildup in the liver not linked to alcohol.
• Hemochromatosis: A condition where too much iron builds up in the body.
• Cirrhosis: Scarring of the liver from long-term damage.
• Bile Duct Obstruction: Blockages caused by gallstones or tumours.
• Drug-Induced Liver Injury: Liver problems from certain medications or overdose (e.g., acetaminophen).
• Other Causes: Conditions like heart failure or thyroid problems can also affect liver function.

If your results are abnormal, your doctor may recommend further tests, such as imaging (like an ultrasound or CT scan), blood tests for viruses, or a liver biopsy. These tests can help identify the problem and decide on the best treatment plan.

Managing Abnormal Liver Function Test Results

When liver function test (LFT) results fall outside the normal range, the approach to management depends on the root cause. Here’s how such situations are typically addressed:

• Lifestyle Changes: If mildly abnormal results stem from issues like fatty liver or alcohol consumption, doctors often recommend adopting healthier habits. This can include eating a balanced diet, regular exercise, weight management, and quitting alcohol.
• Adjusting Medications: In cases where a medication is affecting liver function, your doctor may alter the dosage or switch you to a safer alternative.
• Close Monitoring: Mild abnormalities may not always require immediate intervention. Your healthcare provider might track your results over time to see if they normalise on their own.
• Treating Underlying Conditions: If an underlying liver disease is diagnosed, such as hepatitis or cirrhosis, treatment will focus on addressing the specific condition. This might involve antiviral therapy, lifestyle changes, or specialised care.
• Referral to a Specialist: For more complex or severe cases, you may be referred to a hepatologist, a liver specialist, for further evaluation and advanced treatment options.

Conclusion

Liver function tests (LFTs) provide crucial insights into the health and functionality of the liver. By measuring key enzymes, proteins, and substances, these tests help detect abnormalities early, guide diagnosis, and monitor liver conditions ranging from mild issues to severe diseases like cirrhosis or hepatitis. Understanding the normal range, purpose, and procedure of LFTs empowers individuals to take proactive steps in maintaining their liver health. If abnormal results occur, timely consultation with a healthcare provider is essential to address underlying concerns and safeguard overall well-being. Regular testing, when advised, ensures that the liver continues to function optimally.