What is the Hepatic Steatosis Index (HSI)?
The Hepatic Steatosis Index is a simple screening score used to estimate the likelihood of fatty liver (hepatic steatosis), especially nonalcoholic fatty liver disease (NAFLD), based on routine clinical and lab data.
It is not a diagnosis by itself. Instead, it helps identify who may benefit from additional testing, such as liver ultrasound, elastography, or specialist evaluation.
HSI formula used in this calculator
This tool uses the commonly published HSI equation:
HSI = 8 × (ALT / AST) + BMI + 2 (if female) + 2 (if diabetes is present)
Inputs required:
- ALT (U/L)
- AST (U/L)
- BMI (kg/m²)
- Sex
- Presence of diabetes mellitus
How to interpret your score
- HSI < 30: Lower likelihood of hepatic steatosis.
- HSI 30 to 36: Indeterminate zone; consider clinical context and follow-up testing.
- HSI > 36: Higher likelihood of hepatic steatosis.
Important clinical note
HSI is a screening aid. It does not replace medical assessment. Many factors affect liver health, including alcohol intake, medications, viral hepatitis, metabolic syndrome, and genetics. Always discuss results with a qualified healthcare professional.
When this calculator is useful
- Primary care risk stratification for fatty liver
- Metabolic health check-ins (obesity, insulin resistance, type 2 diabetes)
- Population-level screening conversations
- Tracking context over time alongside labs and clinician guidance
Limitations of HSI
While convenient and low-cost, HSI has limitations:
- It does not measure fibrosis (liver scarring) directly.
- It can be influenced by short-term lab fluctuations.
- It is less reliable outside the populations where it was derived/validated.
- It should be interpreted with full history, exam, and complementary tests.
Practical next steps if your score is elevated
- Review your result with your doctor.
- Discuss additional liver testing (imaging and fibrosis assessment).
- Address metabolic risk factors: weight, glucose, lipids, blood pressure.
- Consider lifestyle interventions: nutrition quality, regular exercise, sleep, and alcohol moderation.
Frequently asked questions
Can I use this calculator to diagnose fatty liver?
No. It is a screening estimate, not a definitive diagnosis.
What if my AST is zero?
AST cannot be zero for this equation because ALT/AST would be undefined. Enter a valid positive AST value from your lab report.
Does a high HSI mean severe liver damage?
Not necessarily. A higher HSI suggests greater likelihood of steatosis, but severity and fibrosis require additional evaluation.
Disclaimer: This educational tool is for informational purposes only and is not medical advice.