π« NAFLD Fibrosis Score Calculator
Advanced fibrosis risk in fatty liver disease.
For informational purposes only, not medical advice. Consult a healthcare professional.
The NAFLD fibrosis score estimates the likelihood of advanced liver fibrosis in nonalcoholic fatty liver disease from routine labs and demographics: age, BMI, diabetes status, AST/ALT ratio, platelets, and albumin. Angulo and colleagues derived it in 2007. Below -1.455, advanced fibrosis is unlikely (about 90% negative predictive value); above 0.676, it is likely; between is indeterminate.
Enter the seven values. The calculator returns the score, the risk band, and the guideline next step: routine monitoring, elastography, or hepatology referral. It is a triage tool that spares low-risk patients liver biopsy.
How to Use This Calculator
Use recent labs: AST, ALT, platelet count, and albumin, plus age, BMI, and whether impaired fasting glucose or diabetes is present. Enter all seven. Read the score against the two cutoffs. Indeterminate scores go to elastography (FibroScan); high scores go to hepatology.
Enter age, BMI, and diabetes status.
Enter AST, ALT, platelets, and albumin from recent labs.
Read the NFS and risk band.
Follow the next step: monitor, elastography, or referral.
The NFS Formula
+ 0.99 x (AST/ALT) - 0.013 x platelets - 0.66 x albumin
The coefficients come from logistic regression on biopsy-staged NAFLD patients. Age and BMI capture exposure time and metabolic load; diabetes adds the largest single increment (1.13) because it strongly predicts fibrotic progression; the AST/ALT ratio rises as fibrosis advances and ALT-predominant injury gives way; falling platelets mark portal hypertension and hypersplenism; falling albumin marks failing synthetic function. The dual cutoffs were chosen for clinical utility: -1.455 maximizes sensitivity to rule out, 0.676 maximizes specificity to rule in, leaving an indeterminate middle where imaging adjudicates.
Worked Example
Age 55, BMI 32, no diabetes, AST 48, ALT 52, platelets 220, albumin 4.2: NFS is -1.350, in the Indeterminate: consider elastography band, so the next step is Elastography (FibroScan). Add diabetes and the score jumps over a full point: the 1.13 diabetes coefficient is the single biggest lever in the formula.
The Three Zones
Low (under -1.455): advanced fibrosis unlikely; continue lifestyle management and periodic reassessment. Indeterminate: the score cannot decide, so vibration-controlled transient elastography measures liver stiffness directly. High (over 0.676): advanced fibrosis likely; hepatology referral for confirmation, variceal and HCC screening, and aggressive metabolic management. Scores track over time: a rising NFS on serial labs deserves attention before it crosses the high cutoff.
Fatty Liver Needs a Doctor's Plan
NAFLD management centers on sustained weight loss (7-10% moves fibrosis), diabetes and lipid control, alcohol avoidance, and medication review. Do not interpret the score as a biopsy result: it is a probability triage. New jaundice, swelling, confusion, or GI bleeding need prompt care. For informational purposes only, not medical advice. Consult a healthcare professional.
Related tools: MELD score, Lille score and BMI calculator.
For informational purposes only, not medical advice. Consult a healthcare professional.
Frequently Asked Questions
What is the NAFLD fibrosis score?
A 7-variable formula estimating advanced fibrosis risk in fatty liver disease from age, BMI, diabetes, AST/ALT, platelets, and albumin.
What NFS rules out fibrosis?
Below -1.455: advanced fibrosis unlikely, with about 90% negative predictive value.
What NFS indicates advanced fibrosis?
Above 0.676 suggests advanced fibrosis and warrants hepatology referral.
What if my score is indeterminate?
Between -1.455 and 0.676: guidelines recommend elastography (FibroScan) to measure liver stiffness directly.
What is the difference between NFS and FIB-4?
Both are noninvasive fibrosis scores; FIB-4 uses age, AST, ALT, and platelets only. They are often used together, with concordant results strengthening confidence.
Can fatty liver be reversed?
Steatosis often reverses with 7-10% weight loss; early fibrosis can stabilize or regress. Advanced cirrhosis does not reverse.
Does normal ALT rule out NASH?
No. Significant steatohepatitis and fibrosis occur with normal ALT, which is why scores use multiple variables.
How often should NFS be rechecked?
Typically yearly with routine labs in NAFLD follow-up, more often when values are changing or indeterminate.
Can the NAFLD fibrosis score replace a liver biopsy?
At the extremes, often yes. A score below -1.455 rules out advanced fibrosis reliably enough that most hepatologists skip the biopsy; above 0.676, advanced fibrosis is likely enough to act on. The middle zone is indeterminate and may still need elastography or biopsy. The score is a triage tool that spares many people an invasive procedure.
How often should NFS be recalculated?
Yearly is reasonable for monitoring, since fibrosis progresses slowly and the inputs (age, labs, BMI, diabetes status) do not swing wildly month to month. Recalculate sooner if something changes meaningfully: new diabetes diagnosis, major weight change, or worsening liver labs. Track the trend; a score drifting upward across years matters more than one reading.
Does a high NFS mean I have cirrhosis?
Not necessarily. The score predicts advanced fibrosis (stages F3 to F4), and only F4 is cirrhosis. A high score warrants referral and confirmation with elastography or biopsy, which stages the fibrosis precisely. Many people with high NFS have F3, which is serious but still has more reversibility than established cirrhosis.