LFT (Liver Function test) test – Disease

🔬 Liver Function Tests (LFTs) in Different Liver Diseases

Liver function tests (LFTs) are used to assess hepatocellular integrity, biliary excretion, and synthetic capacity. These tests help differentiate between various liver diseases such as hepatitis, cirrhosis, cholestasis, fatty liver, and drug-induced liver injury.

🔹 1. Overview of Liver Function Tests

Test	Normal Range	Function
ALT (Alanine Aminotransferase)	7 – 55 U/L	Hepatocellular injury
AST (Aspartate Aminotransferase)	10 – 40 U/L	Hepatocellular injury (also in muscle)
ALP (Alkaline Phosphatase)	44 – 147 U/L	Biliary tract function
GGT (Gamma-Glutamyl Transferase)	9 – 48 U/L	Alcoholic liver disease & cholestasis
Total Bilirubin	0.2 – 1.2 mg/dL	Breakdown of hemoglobin
Direct (Conjugated) Bilirubin	0.1 – 0.4 mg/dL	Excreted via bile
Albumin	3.5 – 5.5 g/dL	Liver’s protein synthesis
Prothrombin Time (PT/INR)	INR < 1.2	Liver’s coagulation ability

🔹 2. LFT Patterns in Different Liver Diseases

1️⃣ Viral Hepatitis (Hepatitis A, B, C, D, E)

Test	Expected Change
ALT & AST	↑↑ (>1000 U/L) (Acute phase)
Bilirubin	↑ (Moderate)
ALP	Normal or Mild ↑
GGT	Normal or Mild ↑
Albumin	Normal (Acute) / ↓ (Chronic)
PT/INR	Normal or Mild ↑

📌 Key Feature: Very high ALT/AST, often ALT > AST, especially in acute viral hepatitis.

2️⃣ Alcoholic Liver Disease (ALD)

Test	Expected Change
ALT & AST	↑ (AST:ALT > 2:1 ratio)
Bilirubin	↑ (in severe cases)
ALP	Mild ↑
GGT	↑↑ (Alcohol-specific marker)
Albumin	↓ (Chronic cases)
PT/INR	↑ (Severe cases)

📌 Key Feature: AST:ALT > 2:1 with significantly elevated GGT.

3️⃣ Non-Alcoholic Fatty Liver Disease (NAFLD)

Test	Expected Change
ALT & AST	Mild ↑ (ALT > AST)
Bilirubin	Normal
ALP	Normal or Mild ↑
GGT	Mild ↑
Albumin	Normal
PT/INR	Normal

📌 Key Feature: Mildly elevated ALT with normal ALP & Bilirubin, associated with obesity, diabetes, and metabolic syndrome.

4️⃣ Cirrhosis (End-Stage Liver Disease)

Test	Expected Change
ALT & AST	Normal or Mild ↑
Bilirubin	↑↑ (Severe cases)
ALP	↑
GGT	↑
Albumin	↓↓ (Liver failure)
PT/INR	↑↑ (Poor prognosis)

📌 Key Feature: Low albumin, prolonged PT/INR, and high bilirubin indicate decompensated cirrhosis.

5️⃣ Cholestatic Liver Disease (Obstruction, PBC, PSC)

Test	Expected Change
ALT & AST	Mild ↑
Bilirubin	↑↑ (Direct > Indirect)
ALP	↑↑
GGT	↑↑
Albumin	Normal or ↓ (Chronic cases)
PT/INR	↑ (Severe cases)

📌 Key Feature: High ALP & GGT with direct hyperbilirubinemia suggest biliary obstruction.

6️⃣ Drug-Induced Liver Injury (DILI)

Test	Expected Change
ALT & AST	↑↑ (>1000 U/L in severe cases)
Bilirubin	↑
ALP	Normal or ↑
GGT	↑ (if cholestatic injury)
Albumin	Normal
PT/INR	↑ (Severe cases)

📌 Key Feature: LFT changes depend on drug type:

Hepatocellular Injury (e.g., Paracetamol, Rifampin) → ALT/AST Dominant
Cholestatic Injury (e.g., Amoxicillin-Clavulanate) → ALP/GGT Dominant

7️⃣ Autoimmune Hepatitis

Test	Expected Change
ALT & AST	↑↑ (>500 U/L in acute flare)
Bilirubin	↑
ALP	Normal or Mild ↑
GGT	Mild ↑
Albumin	↓ (Chronic cases)
PT/INR	↑ (Severe cases)

📌 Key Feature: Very high ALT with positive ANA & SMA antibodies.

8️⃣ Wilson’s Disease (Copper Accumulation)

Test	Expected Change
ALT & AST	↑ (Can be mild or severe)
Bilirubin	↑↑
ALP	↓ (Unlike other liver diseases)
GGT	Normal
Albumin	↓
PT/INR	↑

📌 Key Feature: Low ALP + high bilirubin + Neurological symptoms (Kayser-Fleischer rings).

🔹 Summary Table of LFT Patterns

Disease	ALT/AST	Bilirubin	ALP	GGT	Albumin	PT/INR
Viral Hepatitis	↑↑ (>1000)	↑	Normal or Mild ↑	Normal	Normal (Acute) / ↓ (Chronic)	Normal or ↑
Alcoholic Liver Disease	↑ (AST:ALT >2:1)	↑	Mild ↑	↑↑	↓ (Chronic)	↑ (Severe)
NAFLD	Mild ↑ (ALT > AST)	Normal	Normal	Mild ↑	Normal	Normal
Cirrhosis	Normal/Mild ↑	↑↑	↑	↑	↓↓	↑↑
Cholestatic Disease	Mild ↑	↑↑ (Direct)	↑↑	↑↑	Normal or ↓	↑
Drug-Induced Liver Injury	↑↑ (depends on drug type)	↑	Normal or ↑	↑	Normal	↑ (Severe)
Autoimmune Hepatitis	↑↑ (>500 U/L)	↑	Normal or Mild ↑	Mild ↑	↓ (Chronic)	↑ (Severe)
Wilson’s Disease	↑	↑↑	↓	Normal	↓	↑

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