This fibrosis 4 (FIB4) score calculator reveals whether there is significant liver fibrosis of different stages associated to cirrhosis using patient age, AST & ALT. You can read more about the Fibrosis 4 index, its components and formula and about liver fibrosis below the form.

Patient age:*
AST (IU/L):*
ALT (IU/L):*
Platelet Count (109/L):*

How does this fibrosis 4 (FIB4) score calculator work?

This is a health tool designed to determine significant fibrosis and cirrhosis of the liver with the FIB 4 index in conditions such as NASH (non-alcoholic steatohepatitis) or HCV (hepatitis C virus). There are four criteria to be followed in the model as explained below:

■ Age – There is a correlation between age increase and the progression of fibrosis in the liver, especially in the case of hepatitis C and chronic alcohol consumption but the biological mechanism behind is yet to be established.

■ AST – Aspartate aminotransferase is an enzyme in the amine metabolism and is found in many tissues from liver to heart, kidney or brain. AST levels range between 5 to 40 IU/L and are raised in serum in case of tissue injury.

■ ALT – is similar to AST but found only in the liver therefore an increase above the normal range of 7 to 56 IU/L is indicative of liver damage.

■ Platelet count – This is part of the blood tests and identifies the particles that are responsible with clotting. Decreased values indicate that the liver doesn’t produce enough clotting factors.

This Fibrosis 4 Fib4 score calculator employs the following formula:

Fib 4 score = ( Age x AST ) / ( Platelet count x ( square root of ALT ))

The Fibrosis 4 score

This is a non invasive method based on clinical determinations that indicate the level of fibrosis/ scarring of the liver. It is used especially for Hepatitis C and NASH correlated fibrosis. The set cutoffs for this scoring are:

FIB-4 < 1.45: absence of cirrhosis

FIB-4 between 1.45 - 3.25: inconclusive

FIB-4 > 3.25: cirrhosis

Liver fibrosis

Is the process of scaring in the liver as a result of injury as liver, as many others tissues in the body, regenerates after injury through deposits of new collagen. But this process tends to destroy the normal liver units and the overall function is impaired at several levels. Once fibrosis is extensive, cirrhosis installs and depending on stage, can also lead to liver failure.

All chronic liver diseases are a cause of liver fibrosis but the main are chronic viral hepatitis B and alcoholic liver disease. Chronic hepatitis C (CHC) and non-alcoholic fatty liver disease (NAFLD) are also amongst the causes.

NASH - Nonalcoholic steatohepatitis is similar to alcoholic liver disease but occurs in patients who consume little to no alcohol and is due to fatty deposits in the liver, inflammation and fibrosis. NASH varies in severity with the most serious cases leading to cirrhosis.

Hepatitis C – is the infection caused by HCV and produces liver inflammation that in turn impairs the proper function of the organ.

Example FIB4 calculation

Taking the case of a patient aged 34 with a measured AST value of 65 IU/L; an ALT value of 70 IU/L and the platelet count at 67 109/L. The result is:

Fibrosis 4 (FIB-4) Score = 3.94

For Non-Alcoholic Steatohepatitis (NASH) a FIB-4 score < 1.30 = F0 - F1, while a FIB-4 score > 2.67 = F3 - F4

For Hepatitis C Virus (HCV) a FIB-4 score < 1.45 = F0 - F1, while a FIB-4 score > 3.25 = F3 - F4


1) Martínez SM1, Crespo G, Navasa M, Forns X. Noninvasive assessment of liver fibrosis. Hepatology. 2011 Jan;53(1):325-35.

2) Sterling RK, Lissen E, Clumeck N, et. al. Development of a simple noninvasive index to predict significant fibrosis patients with HIV/HCV co-infection. Hepatology 2006;43:1317-1325.

13 Jun, 2015