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What it measures: fibrosis

Who should take it: anyone concerned about their liver

Where to get it: primary care provider, online calculator

AST to Platelet Ratio Index (APRI) is a blood-based liver test based on the amount of aspartate aminotransferase (AST) and platelets in a person’s body. APRI score measures the amount of fibrosis in the liver. AST is an enzyme that is typically found in low levels in the body; elevated AST levels are caused by a damaged liver and usually indicate cirrhosis. Platelets are blood cells that help heal wounds and stop heavy bleeding; the normal range is 150,000 to 400,000 per microliter (mcL) of blood. Low platelet counts are anything under 150,000/mcL and are usually found in people with cirrhosis. The calculation for APRI can be seen in the following image:

To understand APRI scores, the numbers to keep in mind are 0.5 and 1.5. The lower the score (less than 0.5), the greater the negative predictive value, or the ability to rule out cirrhosis. The higher the score (greater than 1.5), the greater the positive predictive value, or the ability to rule in cirrhosis. A score between 0.5 and 1.5 is indeterminate and requires further testing.[1] It is important to note that APRI alone is probably not sensitive enough to rule out significant disease, and that using multiple tests in combination can help increase diagnostic accuracy.[2]

Though it is not the most specific or sensitive test, it is widely available through analysis of routine bloodwork. If you have your AST and platelet count values from previous bloodwork, you can enter them yourself in the calculator here:



[1] Chou and Wasson, Blood tests to diagnose fibrosis or cirrhosis in patients with chronic hepatitis C virus infection: a systematic review, Annals Internal Medicine, June 2013, doi: 10.7326/0003-4819-158-11-201306040-00005.

[2] Chou and Wasson.