FibroSure (FibroTest) for Fatty Liver Disease Assessment
FibroSure (FibroTest) is an appropriate and validated blood test for assessing liver fibrosis in fatty liver disease, though it should be used as part of a sequential testing strategy rather than as a standalone diagnostic tool. 1
Primary Recommendation
Use FibroTest as a second-line assessment after initial screening with FIB-4 score. FIB-4 should be your first-line test because it's simpler, free, and equally validated 1. Reserve FibroTest for situations where:
- FIB-4 results are indeterminate
- Elastography is unavailable
- You need more precise quantification of fibrosis stage
Diagnostic Performance in NAFLD
FibroTest demonstrates solid accuracy for detecting advanced fibrosis (F2-4) in fatty liver disease:
- Sensitivity: 71-78% at standard cutoffs 2
- Specificity: 66-73% 2
- Area under ROC curve: 0.84 for advanced fibrosis 3
The test performs particularly well for ruling out advanced disease. At a cutoff of 0.30, it achieves 90% negative predictive value for advanced fibrosis 3. This means if FibroTest is below 0.30, you can confidently exclude significant fibrosis in most patients.
Practical Cutoff Values
Use this two-threshold approach 3:
- FibroTest < 0.30: Rules out advanced fibrosis (NPV 90%, sensitivity 77%)
- FibroTest > 0.70: Rules in advanced fibrosis (PPV 73%, specificity 98%)
- FibroTest 0.30-0.70: Indeterminate zone—proceed to elastography or consider biopsy
Comparison to Other Tests
FibroTest performs comparably to other validated scores in NAFLD 2:
- Similar accuracy to NAFLD Fibrosis Score (no significant difference, p=0.26)
- Superior to APRI and FIB-4 in some head-to-head comparisons
- Less accurate than magnetic resonance elastography (MRE), which remains the most accurate noninvasive test 4
The 2025 AASLD systematic review confirms FibroTest has moderate-to-high quality evidence supporting its use across multiple fibrosis stages in hepatitis C, and this validation extends to NAFLD populations 2.
Advantages Over Simple Scores
FibroTest offers quantitative assessment across the full spectrum of fibrosis stages, unlike simpler scores that may not distinguish between adjacent stages 5. It also assesses steatosis (SteatoTest) and inflammatory activity (ActiTest) when used as part of the FibroMAX panel 6.
Important Limitations
Common pitfalls to avoid:
- Age dependency: FibroTest incorporates age, which can lead to false positives in elderly patients with minimal fibrosis
- Acute inflammation: Elevated transaminases from acute hepatitis will falsely elevate scores
- Gilbert syndrome or hemolysis: Affects bilirubin component
- Cost: Proprietary test requiring payment, unlike free FIB-4 calculation
Recommended Testing Algorithm
- Screen all NAFLD patients with FIB-4 (free, simple calculation)
- If FIB-4 indeterminate or unavailable elastography: Use FibroTest as secondary assessment 1
- If FibroTest indeterminate (0.30-0.70): Proceed to transient elastography or MRE
- Reserve biopsy for cases where noninvasive tests are discordant or when you need to assess inflammatory activity for clinical trial enrollment
Prognostic Value
Beyond diagnosis, FibroTest has prognostic value equal to or better than liver biopsy for predicting liver-related complications and death in chronic liver disease 7. This makes it useful for longitudinal monitoring, not just one-time assessment.
Bottom Line for Clinical Practice
FibroTest is a legitimate, well-validated option for NAFLD fibrosis assessment 5, 3. However, given the availability of free alternatives (FIB-4) with similar accuracy and the superior performance of elastography methods, position FibroTest as a second-tier test when FIB-4 is insufficient and elastography is unavailable 1. The test's main advantage is providing a continuous quantitative measure across all fibrosis stages with established prognostic value.