This FIB-4 calculator is a simple tool for assessing the probability of NAFLD liver fibrosis.
FIB-4 score is a powerful instrument for ruling out or confirming a diagnosis of advanced fibrosis. It's most efficient in adults aged 35-65.
We decided to add the functionality of the APRI calculator, so you can get a more complete assessment for your liver's condition. Check the advanced mode button to see this part of the calculator.
➡️Read on to discover the full interpretation of your results for both the FIB-4 index and the APRI score.⬅️
How to use the FIB-4 calculator
To use our F4 fibrosis tool, you'll need to prepare the following blood tests results:
- AST - usually given in U/L (also called: aspartate transaminase/ AspAT/ ASAT/ AAT/ GOT/ SGOT);
- ALT - usually given in U/L (alanine transaminase / alanine aminotransferase/ ALAT/ SGPT); and
- Platelet count - you can find either the number of platelets per mm³, the number of platelets per μL, or the number of platelets * 10⁹ per liter.
Remember, our FIB-4 calculator works best for people aged 35-65 years old. People outside of this bracket may receive a false-positive result.
💡False positive - a situation where a healthy person receives a result that strongly suggests that they are sick.
Check our other calculators to assess various functions of your liver:
Fibrosis-4 score meaning
FIB-4 is used mostly for people with NAFLD (read below), and HCV, HBV, or HIV co-infections. It is a non-invasive fibrosis and subsequent loss of liver function assessment.
- FIB-4 > 3.25 - confirms the presence of fibrosis in 82.1% of patients; and
- FIB-4 > 1.45 - excludes the presence of fibrosis in 94.7% of patients.
NAFLD is an abbreviation for Non-Alcoholic Fatty Liver Disease. NAFLD is the most common liver disease worldwide - it's a condition that, may, over time, lead to an irreversible cirrhosis of the liver, and a permanent loss of liver function. In comparison to NASH (Non-Alcoholic SteatoHepatitis), NAFLD does not consist of liver inflammation. The reasons NAFLD and NASH develop include:
- Metabolic syndrome (connected with obesity, includes, for example, hypertension or type 2 diabetes);
- Drugs, toxins; and
- Inherited metabolic diseases.
Don't hesitate to ask for professional help if you think you may need it.
How to calculate the FIB-4 liver fibrosis score?
The NAFLD fibrosis score can be presented in a single equation:
FIB-4 = (age * AST) / ( platelet count * √ALT)
Note, that the ALT levels need to be square rooted!
The APRI ratio is a simple way to assess the probability of fibrosis progression among patients suffering from hepatitis type C. Check the advanced mode button!
The APRI formula is as follows:
APRI = (AST / upper limit of normal AST) / platelet count
*Most experts suggest using the value of 40 U/L as the upper normal AST level limit - we also decided to use this value in our calculator.
A value of ≥1 means that there is a high possibility of severe cirrhosis. In general, a high APRI value indicates an increased risk of disease progression.
A value <0.5 can rule out the possibility of progression in around 87% of cases.
Other fibrosis scores
Apart from the FIB-4 or APRI score, we use plenty of different fibrosis scores to asses the probability of the liver disease, with varying levels of invasivity. Let's enumerate a few of them: