Liver Function Tests: Comprehensive Guide to LFTs

What are Liver Function Tests?

Liver function tests (LFTs) are blood tests that measure various enzymes and proteins produced by the liver. These tests assess liver health, detect liver disease, and monitor the effectiveness of treatments. The liver is crucial for metabolism, detoxification, and protein synthesis.

Key Components of Liver Function Tests

1. ALT (Alanine Aminotransferase)

An enzyme found primarily in liver cells. Elevated ALT indicates liver damage from hepatitis, cirrhosis, or fatty liver disease. It's more specific to the liver than other enzymes.

2. AST (Aspartate Aminotransferase)

Another liver enzyme also found in heart and muscle cells. Elevated AST can indicate liver disease or heart damage. The AST/ALT ratio helps determine the type of liver damage.

3. Alkaline Phosphatase (ALP)

An enzyme involved in bone and bile duct function. Elevated ALP suggests bile duct obstruction or bone disease. It's used to assess cholestasis and bone metabolism.

4. Bilirubin

A yellow pigment produced from hemoglobin breakdown. Elevated bilirubin causes jaundice and indicates liver dysfunction or bile duct obstruction. Tests measure total and direct bilirubin.

5. Albumin

The primary protein produced by the liver. Low albumin indicates chronic liver disease or malnutrition, as it's essential for maintaining blood pressure and transporting substances.

6. Prothrombin Time (PT)

Measures blood clotting time. Prolonged PT indicates reduced liver production of clotting factors, suggesting advanced liver disease.

Conditions Detected by LFTs

• ✓ Hepatitis (viral, alcoholic, autoimmune)
• ✓ Cirrhosis and liver fibrosis
• ✓ Fatty liver disease (NAFLD)
• ✓ Bile duct obstruction and gallstones
• ✓ Liver cancer
• ✓ Alcohol-related liver disease
• ✓ Drug-induced liver injury

When Should LFTs Be Performed?

LFTs are recommended during routine checkups, when evaluating jaundice or abdominal pain, before starting hepatotoxic medications, in patients with alcohol use disorder, and when monitoring known liver disease or treatment effectiveness.

Preparation and Procedure

Fasting for 8-12 hours before the test is typically recommended. A simple blood draw provides the sample. Results are usually available within 24 hours and are interpreted by our experienced laboratory professionals.