Calculators · Gastroenterology & Hepatology · Classification
R factor (R value) for drug-induced liver injury
Also called R ratio, DILI pattern, R value
Classifies liver injury as hepatocellular, mixed or cholestatic from ALT and ALP multiples of normal.
Fill 4 more fields to see the result.
Formula and scoring
R = (ALT ÷ ALT ULN) ÷ (ALP ÷ ALP ULN).
Exam and ward pearls
- The pattern of injury frames the differential diagnosis (viral, ischaemic, autoimmune for hepatocellular).
- DILI with hepatocellular jaundice carries mortality up to 10% (ACG 2021).
When not to rely on it
- Values exactly 2 or 5 sit on the boundary; conventions differ slightly between consensus documents.
Source
- Chalasani NP, Maddur H, Russo MW, Wong RJ, Reddy KR. ACG clinical guideline: diagnosis and management of idiosyncratic drug-induced liver injury. Am J Gastroenterol. 2021;116(5):878-898. doi:10.14309/ajg.0000000000001259 · PMID 33929376
- Bénichou C. Criteria of drug-induced liver disorders. Report of an international consensus meeting. J Hepatol. 1990;11(2):272-6. doi:10.1016/0168-8278(90)90124-a · PMID 2254635
Formula and cut-offs checked against these sources on 8 Nov 2026. Educational tool for clinicians; it does not replace clinical judgement.