Hepatic Steatosis Index (HSI) Calculator
Hepatic Steatosis Index (HSI) Calculator
Estimate hepatic steatosis from the ALT/AST ratio, BMI, sex and diabetes status — no waist measurement needed.
Hepatic Steatosis Index (HSI)
4 inputs → indexALT 45 U/L, AST 30 U/L, BMI 29, male, no diabetes
Formula
- ALT, AST
- U/L — note this is ALT over AST, the inverse of the De Ritis ratio
- BMI
- kg/m²
- cut-offs
- < 30 rules out, > 36 rules in
Worked example
ALT 45 U/L, AST 30 U/L, BMI 29, male, no diabetes
ALT/AST = 45 ÷ 30 = 1.5
8 × 1.5 = 12
12 + 29 + 0 + 0 = 41.0
Above 36 → steatosis likely
Thresholds
| HSI | Interpretation |
|---|---|
| < 30 | Steatosis unlikely |
| 30 – 36 | Indeterminate |
| > 36 | Steatosis likely |
How it compares with the fatty liver index
The hepatic steatosis index does the same job as the fatty liver index with a different input set. It replaces waist circumference and triglycerides with the ALT/AST ratio and diabetes status, which makes it easier to calculate from a standard record — no tape measure and no fasting lipids required.
The transaminase ratio here is ALT over AST, the inverse of the De Ritis ratio, and it is used because ALT rises relative to AST in simple steatosis. That relationship reverses as fibrosis advances, which introduces a genuine paradox: a patient who progresses to cirrhosis may see their hepatic steatosis index fall even as their liver disease worsens.
Like the fatty liver index it identifies fat, not scarring, and carries the same warning. Steatosis affects a quarter of the adult population and most of those people never develop liver disease; it is fibrosis that determines outcome. Treat a high index as a prompt to calculate FIB-4, not as an endpoint. It was derived in a large Korean health-screening cohort, and while it performs well elsewhere the thresholds have not been re-derived for every population.
Frequently asked questions
What is a normal hepatic steatosis index?
Below 30 makes steatosis unlikely. Above 36 makes it likely. Between the two the index is indeterminate.
Does HSI use AST/ALT or ALT/AST?
ALT divided by AST — the inverse of the De Ritis ratio. ALT rises relative to AST in simple steatosis, which is what the term captures.
Is HSI or FLI better?
They perform comparably. HSI needs no waist measurement or fasting lipids, so it is easier to calculate retrospectively; FLI has been more widely validated in European cohorts.
Can the index fall as liver disease worsens?
Yes, and it is a real limitation. As fibrosis advances the AST/ALT ratio reverses, which lowers the index even though the liver is getting worse. Always assess fibrosis separately.
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References
- Lee JH et al. Hepatic steatosis index: a simple screening tool reflecting nonalcoholic fatty liver disease. Dig Liver Dis. 2010;42(7):503–8.
- EASL-EASD-EASO Clinical Practice Guidelines on the management of MASLD.