Liver risk check
Hepatic steatosis index calculator
The hepatic steatosis index (HSI) uses your ALT, AST, BMI, sex and whether you have diabetes to score how likely it is that the liver holds extra fat. It is a research index from one Korean study. It does not measure scarring, and it is not a diagnosis.
Your numbers
ALT and AST are on a liver panel or comprehensive metabolic panel, in U/L (also written IU/L). Nothing you enter leaves this page.
What you will see
Your hepatic steatosis index, which of the study's three ranges it falls in, and what that range meant in the study.
Educational only, not medical advice. The index cannot diagnose fatty liver or liver scarring.
Source
Lee JH et al., Digestive and Liver Disease 2010 (formula and the 30.0 and 36.0 cut points).
Validated in
10,724 adults having health check-ups, in a study from Seoul National University in Korea: 5,362 with fatty liver disease (NAFLD) and the same number of controls matched for age and sex, split into a group that built the index and a group that checked it.
Limits
A research index for fat in the liver, not scarring. Built in one Korean study; how well it carries over to other groups is not covered by that paper. Not a diagnosis. Not meant for people whose liver fat comes from heavy drinking.
The formula
The study found that a high ALT to AST ratio, a high BMI and diabetes each pointed independently to fatty liver disease, and built the index from them with a logistic regression model (Lee 2010):
HSI = 8 × (ALT ÷ AST) + BMI (kg/m²), plus 2 if female, plus 2 if diabetes
For example, a man without diabetes with ALT 40 U/L, AST 20 U/L and a BMI of 27 scores 8 × 2 + 27 = 43. A woman without diabetes with ALT 20, AST 25 and a BMI of 22 scores 8 × 0.8 + 22 + 2 = 30.4. Because BMI is added as it is, most of the number usually comes from BMI. In the group the index was built in, it had an accuracy (area under the curve) of 0.812 (Lee 2010).
The cut points: under 30 and over 36
| Index | What the study used it for | How it performed |
|---|---|---|
| Under 30.0 | Rule out fatty liver disease | Sensitivity 93.1% (Lee 2010) |
| 30.0 to 36.0 | Neither ruled in nor out | No rule given (Lee 2010) |
| Over 36.0 | Pick out fatty liver disease | Specificity 92.4% (Lee 2010) |
In plain words: of the people in the study who had fatty liver disease, 93.1% scored 30 or more, so a score under 30 made it less likely. Of those without it, 92.4% scored 36 or less, so a score over 36 made it more likely (Lee 2010). Of the people in the building group who scored under 30 or over 36, 85.6% were classed correctly (Lee 2010). The study then checked the index in its second group (Lee 2010). Half of the people in the study had fatty liver disease by design, which is far more than in the general population, and that changes how often a high score is right.
A research index, with limits
The authors described the index as a simple screening tool that could help choose who to send for a liver ultrasound and who needs lifestyle changes (Lee 2010). It comes from one study in Korea. The AASLD guidance notes that ultrasound itself misses smaller amounts of fat, and that a liver that looks normal on ultrasound can still have inflammation or scarring (AASLD 2023).
Fat is not scarring: FIB-4 comes first
The question that matters most in fatty liver disease is whether the liver is scarred (fibrosis) (AASLD 2023). The hepatic steatosis index does not answer it. The American Association for the Study of Liver Diseases recommends FIB-4 as the first test for advanced scarring (AASLD 2023). If you have your age, AST, ALT and a platelet count, use the FIB-4 calculator. The NAFLD fibrosis score is a second scarring score for people who already have fatty liver disease.
Who should think about this
Fatty liver disease is common in people with overweight, type 2 diabetes or high blood pressure, and usually has no symptoms (NIDDK). NIDDK estimates that about 24% of US adults have it (NIDDK). Read fatty liver disease (MASLD), explained for the background. The fatty liver index is another research index for liver fat, built in Italy from BMI, waist, triglycerides and GGT. The AST/ALT ratio calculator explains what comparing the two enzymes can and cannot tell you; note that the index uses ALT divided by AST, the other way round. A high index is a reason to talk to your doctor, not a diagnosis.
Sources
- Lee JH, Kim D, Kim HJ, Lee CH, Yang JI, Kim W, Kim YJ, Yoon JH, Cho SH, Sung MW, Lee HS. Hepatic steatosis index: a simple screening tool reflecting nonalcoholic fatty liver disease. Dig Liver Dis. 2010;42(7):503-508. PMID 19766548. pubmed.ncbi.nlm.nih.gov/19766548/
- Rinella ME, Neuschwander-Tetri BA, Siddiqui MS, et al. AASLD Practice Guidance on the clinical assessment and management of nonalcoholic fatty liver disease. Hepatology. 2023;77(5):1797-1835. doi.org/10.1097/HEP.0000000000000323
- National Institute of Diabetes and Digestive and Kidney Diseases (NIH). Nonalcoholic Fatty Liver Disease (NAFLD) and NASH. www.niddk.nih.gov/health-information/liver-disease/nafld-nash
- National Institute of Diabetes and Digestive and Kidney Diseases (NIH). Definition and Facts of NAFLD and NASH (MASLD and MASH). www.niddk.nih.gov/health-information/liver-disease/nafld-nash/definition-facts
Written and maintained by the uncovermyrisk.com editorial team. We do not have a medical reviewer; every claim links to its primary source above. Last reviewed: 2026-11-01. Spotted an error? See About.