Calculate the Hepatic Steatosis Index (HSI) to screen for non-alcoholic fatty liver disease using ALT, AST, BMI, diabetes status, and sex.
The Hepatic Steatosis Index (HSI) is a validated, non-invasive screening tool for detecting non-alcoholic fatty liver disease (NAFLD) using routinely available laboratory values and clinical parameters. Developed by Lee et al. (2010) from a large Korean cohort and subsequently validated in European and multi-ethnic populations, the HSI uses ALT/AST ratio, BMI, diabetes status, and sex to estimate the probability of hepatic steatosis.
NAFLD affects approximately 25% of the global population and is now the leading cause of chronic liver disease worldwide. It encompasses a spectrum from simple steatosis (fatty liver) to non-alcoholic steatohepatitis (NASH), which can progress to fibrosis, cirrhosis, and hepatocellular carcinoma. Early detection through screening tools like the HSI enables timely lifestyle intervention when disease is most reversible.
This calculator computes the HSI score with validated cutoff interpretation (< 30 rules out NAFLD, ≥ 36 rules in), additionally calculates the Fatty Liver Index (FLI) when triglycerides, waist circumference, and GGT are available, and provides a comprehensive NAFLD risk factor assessment to guide clinical decision-making.
The HSI calculator enables efficient NAFLD screening using routine blood work without additional imaging costs, identifying patients who need further hepatological evaluation and those who can be reassured. Keep these notes focused on your operational context. Tie the context to the calculator’s intended domain. Use this clarification to avoid ambiguous interpretation. Align this note with review checkpoints.
HSI = 8 × (ALT/AST ratio) + BMI + 2 (if diabetes) + 2 (if female). Score < 30: NAFLD ruled out (sensitivity 93.1%). Score ≥ 36: NAFLD ruled in (specificity 92.4%). AUROC = 0.812.
Result: HSI: 38.0 — NAFLD Likely
ALT/AST ratio = 1.25, so HSI = 8 × 1.25 + 28 + 0 + 0 = 38.0. Score ≥ 36 indicates NAFLD is likely, warranting liver ultrasound confirmation.
Non-alcoholic fatty liver disease has become the most common chronic liver condition worldwide, affecting roughly 25% of adults globally. Its prevalence is even higher in patients with obesity (75-100%), type 2 diabetes (50-75%), and metabolic syndrome (80-90%). The condition is increasingly recognized in lean individuals (lean NAFLD, ~7-20% of cases), particularly in Asian populations.
NAFLD encompasses a disease spectrum: simple steatosis (fatty liver) is generally benign, but approximately 20-30% of patients progress to NASH, characterized by hepatocyte injury, inflammation, and ballooning. NASH can further progress to fibrosis and cirrhosis over years to decades. NASH cirrhosis is projected to become the leading indication for liver transplantation. Early detection through screening tools like HSI enables intervention at the reversible stages.
The field is transitioning from NAFLD to MAFLD (Metabolic-Associated Fatty Liver Disease) and MASLD (Metabolic Dysfunction-Associated Steatotic Liver Disease) nomenclature. These positive diagnostic criteria focus on metabolic dysfunction rather than excluding alcohol use, better reflecting the disease pathophysiology. The HSI and similar screening tools remain valid under both naming conventions.
The HSI is a simple scoring system that predicts the presence of fatty liver disease using easily available clinical data: ALT, AST, BMI, diabetes status, and sex. It was validated with an AUROC of 0.812 for detecting ultrasonography-confirmed NAFLD.
HSI < 30 effectively rules out NAFLD (negative predictive value > 90%). HSI ≥ 36 rules in NAFLD (positive predictive value ~90%). Scores between 30-36 are indeterminate and warrant further evaluation.
Both are validated non-invasive NAFLD screening tools. HSI uses ALT, AST, BMI, diabetes, and sex. FLI uses BMI, waist circumference, triglycerides, and GGT. They have similar diagnostic accuracy (AUROC ~0.80-0.85). Using both provides complementary information.
No, the HSI only estimates the presence of hepatic steatosis (fat accumulation). It cannot distinguish simple steatosis from NASH or assess fibrosis stage. For fibrosis assessment, use FIB-4, NFS, or FibroScan.
Non-alcoholic fatty liver disease (NAFLD) is characterized by excess fat accumulation (≥ 5%) in the liver without significant alcohol consumption. It ranges from simple steatosis to NASH (with inflammation), which can progress to cirrhosis.
The primary treatment is lifestyle modification: weight loss of 7-10% body weight significantly reduces liver fat. Regular exercise (150+ min/week), Mediterranean diet, avoiding sugar-sweetened beverages, and limiting alcohol are key. Medications (pioglitazone, vitamin E) are used in selected NASH cases.