Question 1

What is the R-factor for liver injury?

Accepted Answer

R-factor = (ALT / upper limit of normal for ALT) ÷ (ALP / upper limit of normal for ALP). R > 5 indicates a hepatocellular pattern, R < 2 indicates cholestatic, and 2–5 is mixed. It is the standard pattern classifier endorsed by ACG and EASL drug-induced liver injury guidelines.

Question 2

What does AST/ALT > 2 mean?

Accepted Answer

An AST-to-ALT ratio greater than 2 at modest enzyme elevations is classic for alcoholic hepatitis. It is also seen in advanced cirrhosis (regardless of cause) and occasionally in Wilson disease. Very high transaminases (>500) with AST/ALT > 2 suggests ischemic ("shock liver") injury more than alcohol.

Question 3

When should I order GGT?

Accepted Answer

Order GGT when ALP is elevated to determine whether the source is hepatic or bone. Hepatic ALP elevation comes with elevated GGT; bone ALP (Paget, healing fracture, adolescent growth) does not. Isolated GGT elevation can occur with alcohol or enzyme-inducing drugs without clinically meaningful liver disease.

Question 4

What causes massive transaminase elevation (>1000)?

Accepted Answer

The classic differential is short: ischemic hepatitis ("shock liver"), acute viral hepatitis (A, B, E commonly), acetaminophen toxicity, other drug-induced injury, autoimmune hepatitis flare, and acute biliary obstruction with cholangitis. The clinical context usually narrows it quickly — hypotension favors ischemic, exposure history favors drug, jaundice with RUQ pain favors stone.

Question 5

What is an isolated direct hyperbilirubinemia?

Accepted Answer

A predominantly direct (conjugated) hyperbilirubinemia with normal enzymes is uncommon. Think Dubin-Johnson syndrome and Rotor syndrome (both benign hereditary), sepsis-related cholestasis, very early biliary obstruction before enzymes have risen, or severe systemic illness.

Question 6

How do I separate Gilbert syndrome from hemolysis?

Accepted Answer

Both produce indirect (unconjugated) hyperbilirubinemia. Gilbert is benign, fluctuates with stress / fasting / illness, and the rest of the CBC is unremarkable. Hemolysis usually comes with anemia, elevated LDH, low haptoglobin, and elevated reticulocyte count. A normal CBC and LDH with mild fluctuating indirect bilirubin is essentially Gilbert until proven otherwise.

LFT Pattern Interpreter (R-factor)

References

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