This calculator is for general information and education. It is not medical advice and does not replace the judgment of a doctor, nurse or pharmacist who knows the full clinical picture.
A simple score from liver enzymes and BMI
The hepatic steatosis index (HSI), published by Jeong-Hoon Lee and colleagues in 2010 from a Korean cohort, screens for fatty liver disease with values that are almost always available: the liver enzymes ALT and AST, body mass index, sex and diabetes status.
The formula
HSI = 8 × (ALT ÷ AST) + BMI + 2 (if female) + 2 (if diabetes)
In fatty liver disease, ALT (alanine aminotransferase) usually rises more than AST, so a high ALT-to-AST ratio points to the liver fat typical of metabolic disease. In alcohol-related liver disease and advanced fibrosis, the ratio often reverses: the AST-to-ALT ratio (De Ritis ratio) climbs above 1.
Example
A man with an ALT of 40 U/L, an AST of 30 U/L, a BMI of 27 and no diabetes scores 8 × 1.33 + 27 = 37.7.
| HSI | Interpretation |
|---|---|
| under 30 | Fatty liver unlikely |
| 30 to 36 | Indeterminate |
| above 36 | Fatty liver likely |
In the original study, an HSI under 30 ruled out fatty liver with a sensitivity of about 93%, and above 36 detected it with a specificity of about 92%.
HSI or FLI?
Both scores perform similarly in most studies. The fatty liver index needs triglycerides, GGT and waist circumference; the HSI needs only liver enzymes and BMI, so it is useful when a full lipid panel or waist measurement is missing.
What a high score means
A positive screen calls for an assessment of liver fibrosis, the key prognostic factor, typically with the FIB-4 score and elastography. Normal liver enzymes do not exclude fatty liver: many people with MASLD have an ALT in the normal range.
Limits
- Muscle injury, intense exercise and some drugs raise AST or ALT.
- Cut-offs were derived in Asian adults; BMI thresholds for obesity differ between populations.
- The HSI does not measure fibrosis or inflammation.