How do you explain elevated Liver Function Tests (LFTs) to a patient?

How to Explain Elevated Liver Function Tests to a Patient

When explaining elevated LFTs to your patient, start by clarifying that these tests don't actually measure how well the liver is working—they detect liver cell injury or bile flow problems, not liver function itself. 1, 2

What LFTs Actually Measure

• LFTs are misleadingly named: They primarily detect damage to liver cells (hepatocytes) or blockages in bile flow, rather than measuring the liver's ability to perform its essential functions like making proteins or clearing toxins 1, 2

• True liver function is assessed by measuring what the liver produces (albumin) and how well blood clots (prothrombin time/INR), not by the standard "liver function tests" 1, 2

Breaking Down the Numbers for Patients

The Two Main Patterns

Pattern 1: Liver Cell Injury (Hepatocellular Pattern)

• ALT and AST are elevated much higher than alkaline phosphatase 1
• Explain that ALT (alanine aminotransferase) is the most specific marker for liver damage because it's concentrated almost exclusively in liver cells 1
• AST (aspartate aminotransferase) can also come from heart, muscles, kidneys, and blood cells, so it's less specific 1
• Normal ALT: 29-33 IU/L in men, 19-25 IU/L in women 1

Pattern 2: Bile Flow Problems (Cholestatic Pattern)

• Alkaline phosphatase (ALP) is elevated more than ALT/AST 1
• This suggests bile isn't flowing properly, either from blockage or impaired bile production 1

Severity Classification to Share

Mild elevation: Less than 5 times the upper normal limit 1, 3

• Most common causes: fatty liver disease (from obesity/diabetes or alcohol), medications, viral hepatitis 1, 3

Moderate elevation: 5-10 times normal 1, 3

Severe elevation: Greater than 10 times normal 1, 3

Life-threatening: Greater than 20 times normal—requires immediate hospitalization 3

Common Causes to Discuss

For Hepatocellular Pattern (High ALT/AST):

• Fatty liver disease (most common): From obesity, diabetes, or metabolic syndrome 1, 3
• Alcohol-related liver disease: If AST is more than twice ALT, alcohol is likely 2
• Viral hepatitis: Hepatitis B or C 1, 3
• Medications and supplements: Including over-the-counter drugs and herbal products 1, 3
• Acetaminophen (Tylenol): Can cause severe liver damage if taking more than 6 tablets daily or combined with alcohol 4

Less Common Causes:

• Autoimmune hepatitis, hemochromatosis (iron overload), Wilson disease (copper accumulation), alpha-1 antitrypsin deficiency 1

Critical Context to Provide

Normal doesn't mean no disease: 30% of routine LFTs show at least one abnormal value, but only 3.9% of patients with abnormal results actually have significant liver disease within 5 years 2

Conversely, normal LFTs don't exclude liver disease: The liver can be severely damaged with cirrhosis or portal hypertension while tests remain normal until late stages 2

What Happens Next

For Mild Elevations (<5× normal):

• Monitor weekly until values normalize 3
• Eliminate potential causes: stop unnecessary medications, reduce alcohol to zero, address obesity/diabetes 3
• Recheck in 3-6 months if initial workup is unrevealing 3

For Moderate to Severe Elevations (5-20× normal):

• Monitor every 2-3 days until stable or improving 3
• Immediate workup for viral hepatitis, autoimmune disease, and imaging studies 3

For Life-Threatening Elevations (>20× normal):

• Immediate hospitalization for intensive monitoring 3

Additional Testing Needed

• Blood work: Complete blood count, kidney function, blood sugar, lipid panel, thyroid tests, viral hepatitis markers 3
• Ultrasound: Essential to look for fatty liver, masses, bile duct blockage, and assess liver texture 3, 2
• Fibrosis assessment: If no clear acute cause, calculate FIB-4 score to determine if advanced scarring is present (score <1.3 suggests low risk; <2.0 if over age 65) 2

When to See a Specialist

Refer to hepatology for: 3

• Persistent unexplained elevations after initial workup
• ALT greater than 5 times normal
• Evidence of advanced fibrosis on scoring
• Signs of liver failure (confusion, fluid retention, bleeding)

Key Pitfalls to Avoid

• Don't assume muscle injury isn't the cause: Check creatine kinase (CK) to rule out muscle damage causing elevated AST 3
• Don't forget medication history: Include ALL prescription drugs, over-the-counter medications, vitamins, and herbal supplements 1, 3
• Don't ignore alcohol: Even "social drinking" of 3+ drinks daily while taking acetaminophen can cause severe liver damage 4
• Don't overlook the pattern: Whether it's hepatocellular versus cholestatic guides the entire diagnostic approach more than absolute numbers 2