This AST to Platelet Ratio Index APRI calculator computes the APRI score based on the platelet count and AST value to check for cirrhosis signs. You can read more about the formula used and the accuracy of the test below the form.

AST Level:*
Upper limit of Normal AST (IU/L):*
Platelet Count (109/L):*

How does this AST to platelet ratio index APRI calculator work?

This is a health tool that takes the AST score into account and the platelet count and delivers the APRI (AST to Platelet Ratio Index) score. There are three fields in the calculator, the AST (aspartate aminotransferase) input in IU/L, the upper AST limit, set default at 40 IU/L but which can be modified according to need and the platelet count 109/L, value which should be between 0 and 600 because the other zeros in the count are already being taken in consideration.

The formula used is the following:

APRI = AST (IU/L) / AST upper normal limit (IU/L) /Platelet count (109/L) *100

Interpretation of APRI

- APRI is considered a simple and non invasive method to roughly analyze the risk of hepatic fibrosis or in general advanced liver damage. It is the latest non invasive test to be introduced and aims to become a surrogate marker of liver fibrosis in hepatitis C virus (HCV) patients. To this point, the standard testing involved liver biopsy.

- The aspartate aminotransferase to platelet ratio index can be used as alternative diagnosis but its accuracy is not considered strong enough to be used on its own, but it does provide a quick outlook of the situation.

- Any APRI value greater below 0.5 rules out significant fibrosis while all values above 0.5 are to be indicative for some kind of liver damage. Also scores that are higher than 0.7 are considered a significant sign for hepatic fibrosis.

- APRI scores higher than 1 are an indicator of cirrhosis to a sensitivity of 76%.

- APRI is also relevant in NAFLD where was noticed an increase in this index with the degree of fibrosis.

Example calculation

Let’s take the case of a patient with an AST value of 65, considering the upper value set at 40 and with a platelet count of 458 109/L. The computed APRI value is 65/40/458 *100 = 0.35


1) Lin ZH, Xin YN, Dong QJ, et al. (2011) Performance of the aspartate aminotransferase-to-platelet ratio index for the staging of hepatitis C-related fibrosis: an updated meta-analysis. Hepatology; 53:726-36.

2) Loaeza-del-Castillo A, Paz-Pineda F, Oviedo-Cárdenas E, Sánchez-Avila F, Vargas-Vorácková F. (2008) AST to platelet ratio index (APRI) for the noninvasive evaluation of liver fibrosis. Ann Hepatol; 7(4):350-7.

12 Jun, 2015