The calculation runs in your browser; no data is sent or stored. The result is for information only and does not replace assessment by your doctor. Under the age of 35 the score is not precise enough, and transaminases can vary from one blood test to the next — see the limitations of the FIB-4 index.
What is the FIB-4 index?
FIB-4 is a score calculated from four pieces of information you already have on a routine blood test: age, AST (SGOT), ALT (SGPT) and the platelet count. It estimates the likelihood that the liver has advanced fibrosis, that is significant scarring, without needing special investigations at this first stage. It is used as a triage test, particularly in people with fatty liver.
How is the result interpreted?
Below 1.3, the risk of advanced fibrosis is low, and the score can be repeated periodically [1]. Between 1.3 and 2.67 is an indeterminate zone, where the doctor usually recommends an additional test, such as liver elastography (measuring liver stiffness with devices like FibroScan) [1]. Above 2.67, the risk is high and specialist assessment is needed [1]. In people aged 65 or older, the lower cut-off used is 2.0 instead of 1.3, because age raises the score on its own [2].
How is FIB-4 linked to diabetes?
Fatty liver associated with metabolic dysfunction (MASLD) is very common in people with type 2 diabetes and can progress silently to fibrosis. MASLD stands for metabolic dysfunction-associated steatotic liver disease; it was previously called non-alcoholic fatty liver disease. In people with type 2 diabetes, or with prediabetes plus risk factors, FIB-4 is calculated periodically [1]. The aim is to identify early those who need further liver investigations. What ties the two together most often is the fat around the abdomen, and where it sits is shown by the waist-to-height ratio.
What are the limitations of the FIB-4 index?
FIB-4 does not diagnose fibrosis; it only guides triage. Under the age of 35, the score is not precise enough to confirm or rule out advanced fibrosis [2]. At this age, the doctor uses other tests, such as liver elastography [2]. Transaminases can fluctuate for several reasons (medicines, alcohol, infections), which complicates interpreting the score. A result in the indeterminate or high zone does not mean you have fibrosis, only that further assessment is worthwhile. Discuss the result with your doctor.