Understanding Liver Function Tests (LFTs): Normal vs Optimal Ranges

?What is a Liver Function Tests (LFTs)?

Liver Function Tests (LFTs) are a group of blood tests that assess liver health by measuring enzymes, proteins, and bilirubin. They detect liver damage, inflammation, infection, and monitor conditions like hepatitis, fatty liver disease, and cirrhosis.

What Does It Measure?

• ALT (SGPT) — enzyme released when liver cells are damaged
• AST (SGOT) — enzyme found in liver, heart, and muscles
• Alkaline Phosphatase (ALP) — enzyme related to bile ducts
• Bilirubin (Total, Direct, Indirect) — waste product from RBC breakdown
• Albumin — protein made by liver
• Total Protein — measure of liver synthetic function
• GGT — enzyme sensitive to alcohol and bile duct issues

!Why It Matters

The liver performs 500+ functions including detoxification, protein synthesis, and bile production. LFTs detect fatty liver disease (NAFLD/MASLD) — now affecting 25% of adults — as well as hepatitis, alcohol-related damage, and medication-induced liver injury. Early detection prevents progression to cirrhosis.

Component Breakdown

How to Prepare

• Fast for 8–12 hours (some components affected by food)
• Avoid alcohol for at least 24 hours (ideally 72 hours) before test
• Tell your doctor about medications — many affect liver enzymes
• Avoid intense exercise 24 hours before (can raise AST)

What Do Results Mean?

Mild ALT/AST elevation (2-3x normal) suggests fatty liver disease, medication effect, or alcohol. Marked elevation (>10x) suggests hepatitis, severe injury, or acute liver failure. High ALP with high GGT suggests bile duct obstruction. Low albumin suggests chronic liver disease or malnutrition. Isolated high bilirubin may be Gilbert's syndrome (benign).

Next Steps

Mild elevations: repeat in 1-3 months, check for fatty liver with ultrasound. Significant elevations: viral hepatitis panel, autoimmune markers, medication review, liver ultrasound or FibroScan. Persistent abnormalities may need hepatology referral.

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