Calculate the FIB-4 index from age, AST, ALT and platelets to stratify liver fibrosis risk.
Result
How to use this tool
AST and ALT in U/L and platelets in x10^9/L, from the same blood draw.
The advanced section records whether chronic liver disease is already known.
Low, indeterminate or high risk of advanced fibrosis.
These usually lead to elastography, further blood tests or liver referral.
Formula & worked example
Age 55, AST 60 U/L, ALT 45 U/L and platelets 180 gives 55 x 60 / (180 x sqrt(45)) = 3300 / 1207.5 = 2.73, a high-risk score.
Limitations — read this before you rely on it
Educational use only. This tool is for education only and is not medical advice. Talk to a clinician about any result that worries you, and never change treatment because of a calculator result.
Frequently asked questions
It triages people at risk of advanced liver fibrosis (for example with fatty liver disease) into low, indeterminate and high risk, so only some need elastography or biopsy.
Below 1.3 is low risk (2.0 over age 65) and above 2.67 is high risk. Scores between are indeterminate.
No. A high score raises the probability of advanced fibrosis but does not prove cirrhosis, and a low score does not exclude all liver disease.
Age is in the numerator, so scores rise with age even with normal bloods; that is why the low cut-off is raised to 2.0 over age 65.
Muscle injury or heavy exercise, alcohol, many medicines, hepatitis and gallstones can all raise transaminases and distort the score.