Liver Function Test (LFT)

The Liver Function test (LFT) is a simple blood test that checks how well your liver is working. It measures key enzymes, proteins, and bilirubin levels in your blood. Together, these values give your doctor a clear picture of your liver health and help detect early signs of damage or disease.

Doctors order an LFT to check how well the liver is functioning and to look for signs of liver damage or disease. The liver performs over 500 functions, including filtering toxins, producing clotting proteins, digesting fats through bile, and storing energy. Because the liver works so hard, it is prone to damage from infections, alcohol, medications, and chronic diseases. The LFT is one of the primary tools doctors use to assess liver health and detect early signs of stress or dysfunction.

The LFT monitors liver enzymes (which leak into the blood when liver cells are damaged), proteins made by the liver such as albumin, and bilirubin (a waste product processed by the liver). Any fluctuation in these values signals a possible liver abnormality. Suitable for all ages and genders, no fasting is required for this test, and the results are available within 11 hours.

A Liver Function test is performed as a routine screening test or when symptoms suggest the liver may not be functioning properly. This test helps doctors detect early liver damage, monitor ongoing conditions, and assess liver fitness before surgery.

This test is usually recommended for:

• Anyone with abdominal pain (especially upper right side), jaundice, dark urine, pale stools, nausea, or unexplained fatigue.
• Individuals with fluid retention or swelling in the abdomen (ascites), abnormal bleeding, or unexplained weight loss.
• Anyone with a known liver disease, such as hepatitis, cirrhosis, or fatty liver - for regular monitoring.
• Regular alcohol drinkers - alcohol is one of the leading causes of liver damage and elevated liver enzymes.
• Patients on long-term medications such as statins, antitubercular drugs, anticonvulsants, or paracetamol.
• Patients diagnosed with diabetes, obesity, or metabolic syndrome - closely linked to non-alcoholic fatty liver disease (NAFLD).
• Pre-surgical patients - the LFT is a standard part of the pre-surgery profile to confirm liver fitness before anaesthesia.

The frequency of the LFT depends entirely on your diagnosis and your doctor's advice. It can range from daily monitoring in acute cases to monthly checks in chronic conditions. Liver enzyme levels can change quickly in acute illness, so the timing for repeating the test varies significantly.

The LFT is a powerful first-line screening tool for a wide range of liver and bile-related conditions. While it does not confirm a specific disease on its own, an abnormal LFT is a reliable early-warning signal that guides your doctor's next steps. The LFT may provide early warnings for:

• Jaundice - Elevated bilirubin causes yellowing of the skin and eyes. The LFT helps identify whether the cause is liver cell damage, bile duct obstruction, or red blood cell breakdown.
• Hepatitis - Viral hepatitis (A, B, C, D, E) causes significant elevation in liver enzymes (SGPT and SGOT), which the LFT picks up reliably.
• Cirrhosis - Advanced liver scarring from long-term damage. Low albumin and abnormal PT are key markers of cirrhosis.
• Fatty Liver Disease (NAFLD and AFLD) - Fat accumulation in the liver causes mild to moderate elevation in SGPT and GGT levels.
• Alcoholic Liver Disease - Heavy alcohol use raises GGT significantly and is often the first abnormality seen on the LFT.
• Gallbladder Disease and Cholestasis - Blockage of bile ducts causes elevated ALP and bilirubin.
• Liver Cancer (Hepatocellular Carcinoma) - Elevated enzymes and reduced albumin can signal liver involvement in cancer.
• Drug-Induced Liver Injury (DILI) - Many commonly used drugs can raise liver enzymes, which the LFT monitors.

Important Note: The LFT result may indicate liver damage, but may not precisely pinpoint the condition. Your doctor will use results alongside symptoms and other investigations to make a complete assessment.

What to Expect Before the LFT

No fasting is required for a standalone LFT. You can eat and drink normally. If it is being done alongside a fasting blood sugar or lipid profile, your doctor may advise fasting for 8 to 12 hours. Inform your doctor about all current medications, alcohol consumption in the past 24 to 48 hours (which can raise GGT), and any strenuous exercise; avoid intense physical activity for 24 hours before the test.

What to Expect During the Blood Collection

A phlebotomist cleans the skin with an antiseptic, then places an elastic band around your upper arm to make the veins easier to access. A small needle is inserted into the vein; you may feel a brief pinch. Blood is collected into a labelled tube in under a minute. All LFT parameters are tested from a single blood sample.

What to Expect After the LFT

A small cotton swab and bandage are placed over the site to stop any minor bleeding. You can return to normal activities immediately. Minor bruising is normal and disappears quickly. If dizzy, sit and relax for a few minutes before leaving.

The LFT includes 12 parameters, grouped by what they measure:

Liver Enzymes (Released When Liver Cells Are Damaged)

• SGPT / ALT (Alanine Transaminase) - An enzyme found primarily in the liver. When liver cells are damaged or inflamed, ALT leaks into the blood. It is the most specific marker for liver damage and the first value your doctor will look at.
• SGOT / AST (Aspartate Transaminase) - Found in the liver, heart, skeletal muscle, and kidneys. Elevated AST can indicate liver damage or muscle injury. When both SGPT and SGOT are elevated, liver disease is strongly suspected.
• ALP (Alkaline Phosphatase) - Found in the liver, bones, intestines, and placenta. High ALP suggests bile duct obstruction (cholestasis), bone disease, or certain liver conditions.
• GGT (Gamma-Glutamyl Transpeptidase) - Primarily produced in the liver. A highly sensitive marker for liver and bile duct disease. Frequently elevated in people who consume alcohol heavily.
• SGOT/SGPT Ratio - A comparison of AST to ALT levels that helps identify the underlying cause of liver damage.

Liver Proteins (Made by the Liver)

• Serum Albumin - The main protein made by the liver. Low albumin indicates the liver is not producing enough protein, a sign of significant liver damage or chronic liver disease.
• Serum Globulin - Proteins produced by the liver and the immune system. The Albumin to Globulin (A/G) ratio helps assess overall liver protein production and immune function.
• A/G Ratio (Albumin to Globulin Ratio) - A low A/G ratio can indicate chronic liver disease, kidney disease, or autoimmune conditions.
• Total Protein:The combined measurement of albumin and globulin in the blood. Abnormal levels may indicate liver disease, kidney problems, malnutrition, or chronic inflammatory conditions.

Bilirubin (Waste Product Processed by the Liver)

• Total Bilirubin - A yellow waste product formed when red blood cells break down. Elevated total bilirubin causes jaundice.
• Direct (Conjugated) Bilirubin - The processed form of bilirubin. High direct bilirubin typically indicates bile duct obstruction or liver cell damage.
• Indirect (Unconjugated) Bilirubin - The unprocessed form. High indirect bilirubin typically suggests haemolytic anaemia or Gilbert's syndrome.

The table below shows the standard reference ranges for all LFT parameters. If any value falls above or below these ranges, it signals your doctor to investigate further rather than confirm the disease.

Important Note: Certain enzyme levels are marginally higher in children, especially infants. There may also be a minimal difference in normal LFT values between males and females. Normal reference ranges may vary slightly from lab to lab. Always refer to the ranges mentioned in your specific report and consult your doctor.

If one or more LFT values are outside the normal range, it may signal that your liver is under stress or experiencing damage. The table below explains what elevated or abnormal values for each parameter may indicate.

Disclaimer: This table is for educational purposes and provides a risk assessment only. These findings do not confirm a diagnosis. Factors like age, gender, medications, alcohol use, and recent exercise can all affect LFT values. Always consult your doctor to understand how these results relate to your symptoms and overall health.

Potential Risks and Complications

The LFT is a very safe, routine blood test. Complications are extremely rare, and most people feel only a brief pinch. Consult a doctor if: the puncture site does not stop bleeding after applying gentle pressure; you notice unusual pain, redness, warmth, or swelling at the needle site; or you feel persistently lightheaded after the blood draw. Sit and rest for a few minutes before leaving.

Understanding LFT Limitations

The LFT cannot confirm a specific disease on its own. Abnormal values are a starting point, not a final diagnosis, and your doctor will always investigate further using imaging or a liver biopsy if needed. A normal LFT does not guarantee a completely healthy liver, as early-stage fatty liver or early fibrosis may not produce abnormal values until significant damage has occurred. LFT values can also be temporarily affected by strenuous exercise, alcohol in the past 24 to 48 hours, or certain medications. Always disclose these factors to your doctor.

If your LFT results are abnormal, your doctor may recommend follow-up tests to identify the specific cause and extent of liver involvement.

Pro Tip: For the most stress-free experience, book your LFT on PharmEasy. No fasting required - get your sample collected at home at your convenience and receive your digital report the same day.