R_factor_for_liver_injury v.1
R Factor for Liver Injury differentiates cholestatic from hepatocellular liver injury, recommended by ACG guidelines. Use for patients with suspected drug induced liver injury (DILI) with abnormal liver chemistries.
To differentiate cholestatic from hepatocellular liver injury.
Use the first lab values (ALT and ALP) indicating acute liver injury to calculate the R factor. FORMULA R Factor = ( patient’s ALT / upper limit of normal ALT ) / ( patient’s ALP / upper limit of normal ALP ) Note: calculator uses 40 U/L as upper limit of normal ALT and 120 U/L as upper limit of normal ALP. Normal values may vary by lab. Interpretation: R Factor Injury type Recommended 1st line tests >5 Hepatocellular Acute viral hepatitis serologies, HCV RNA and autoimmune hepatitis serologies, imaging studies (e.g. abdominal ultrasound) 2–5 Mixed Acute viral hepatitis serologies, HCV RNA and autoimmune hepatitis serologies, imaging studies (e.g. abdominal ultrasound) <2 Cholestatic Imaging studies (e.g. abdominal ultrasound)
1. Bénichou C. Criteria of drug-induced liver disorders. Report of an international consensus meeting. J Hepatol. 1990;11(2):272-6.
OBSERVATION.lab_test-alt.v1, OBSERVATION.lab_test-alp.v1, EVALUATION.r_factor_for_liver_injury.v0
