Normal range: 0 – 1.3 (lower is better)
FIB-4 is a simple score that estimates the likelihood of advanced liver fibrosis (scarring) without a biopsy. It combines your age, two liver enzymes (AST and ALT), and your platelet count into a single number. It is widely used as a first-pass screen for liver fibrosis, especially in people with fatty liver disease. A score below 1.3 makes significant fibrosis unlikely, while a score above 2.67 raises concern and usually warrants further evaluation. Scores in between fall in an indeterminate zone.
A normal FIB-4 is 0 – 1.3. Lower is better.
A rising FIB-4 reflects the changes that accompany advancing liver fibrosis: AST climbing relative to ALT, and platelet counts falling as the liver and spleen are affected. The most common underlying driver is non-alcoholic fatty liver disease, which is closely tied to insulin resistance, excess weight, and metabolic syndrome. Alcohol-related liver disease and chronic viral hepatitis also raise the score.
Because age is part of the formula, FIB-4 naturally trends higher with age, and the standard cutoffs are less reliable in people over 65. Anything that independently lowers platelets or raises AST (including muscle injury) can also nudge the score upward.
The most effective ways to improve the factors behind FIB-4 are losing excess weight, reducing alcohol, cutting sugar and refined carbs, and exercising regularly. These changes lower liver enzymes and can slow or reverse early fibrosis.
FIB-4 comes in a comprehensive metabolic panel (about $29–$55). Empirical's $190 panel adds ALT, AST, and 100+ other biomarkers.
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