R factor for liver injury pattern

Classifies drug-induced liver injury as hepatocellular, cholestatic, or mixed.

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Inputs

2 of 4

ALT

U/L

ALT upper limit of normal

U/L

Alkaline phosphatase

U/L

ALP upper limit of normal

U/L

When to use

Pearls and pitfalls

R 5 or higher: hepatocellular; 2 or lower: cholestatic; between: mixed.
Hy's law: ALT above 3× ULN with bilirubin above 2× ULN signals high mortality risk.

Why use

Determines the DILI workup and causality assessment.

R = (ALT ÷ ALT ULN) ÷ (ALP ÷ ALP ULN)