LIVER FUNCTION TEST (LFT)

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LIVER FUNCTION TEST (LFT)

1. What is Liver Function Test (LFT)?

Liver Function Tests (LFTs) are a group of blood tests used to evaluate the health and functioning of the liver. These tests measure the levels of liver enzymes, proteins, and waste products in the blood. They help diagnose liver diseases, detect liver damage, monitor disease progression, and assess the effectiveness of treatment. LFTs also identify problems related to bile ducts and the liver’s ability to produce proteins and clotting factors. Doctors commonly recommend LFTs when symptoms such as jaundice, abdominal pain, fatigue, or abnormal liver function are suspected. LFTs play an important role in early diagnosis and disease management.

2. When is LFT Recommended?

Liver Function Tests are recommended whenever liver disease or liver damage is suspected. Doctors advise LFTs for patients with symptoms such as jaundice, fatigue, abdominal pain, nausea, dark urine, or pale stools. They are commonly performed to diagnose hepatitis, fatty liver disease, alcohol-related liver damage, and drug-induced liver injury. LFTs are also useful before starting medications that may affect the liver and during routine health check-ups. Individuals with obesity, diabetes, excessive alcohol consumption, or a family history of liver disease may also require regular LFT monitoring to detect liver problems at an early stage.

3. ALT (Alanine Aminotransferase)

Alanine Aminotransferase (ALT) is an enzyme found mainly in liver cells. Normally, only small amounts of ALT are present in the bloodstream. When liver cells are damaged due to infections, inflammation, toxins, or injury, ALT leaks into the blood, causing its level to rise. Therefore, ALT is considered one of the most liver-specific enzymes. Elevated ALT levels are commonly seen in hepatitis, fatty liver disease, liver cirrhosis, and drug-induced liver injury. Monitoring ALT helps doctors assess the severity of liver damage and evaluate the response to treatment. The normal range is approximately 7–56 U/L.

4. AST (Aspartate Aminotransferase)

Aspartate Aminotransferase (AST) is an enzyme present in the liver, heart, skeletal muscles, kidneys, and brain. Unlike ALT, AST is not specific to the liver. Increased AST levels may indicate liver diseases such as hepatitis or cirrhosis, but they can also result from muscle injury, heart attack, or strenuous exercise. Therefore, AST is usually interpreted together with ALT to determine the cause of elevated enzyme levels. A higher ALT compared to AST generally suggests liver disease. The normal AST level ranges from 10–40 U/L, depending on the laboratory reference values.

5. ALP (Alkaline Phosphatase)