Is a FibroSure (FibroTest) test required to diagnose hepatic steatosis in a patient with non‑alcoholic steatohepatitis (NASH)?

FibroSure/FibroTest is NOT Required to Diagnose Hepatic Steatosis

FibroSure (FibroTest) is not needed to diagnose hepatic steatosis itself—ultrasound is the primary screening modality for detecting steatosis. However, FibroSure may be useful as a secondary test to assess for advanced fibrosis in patients with NAFLD, though simpler non-proprietary scores like FIB-4 should be used first 1, 2, 3.

Understanding the Clinical Context

The question conflates two distinct diagnostic goals:

1. Diagnosing hepatic steatosis (fat in the liver)
2. Assessing for advanced fibrosis in patients with NAFLD/NASH

These require different approaches, and FibroSure addresses only the second issue.

Diagnosing Hepatic Steatosis

Abdominal ultrasound is the primary screening modality for hepatic steatosis 4. It has high accuracy (>80%) for detecting moderate-to-severe steatosis, though sensitivity drops for mild steatosis (<30% fat content) 1, 4.

In high-risk patients (those with diabetes, metabolic syndrome, or obesity), you can skip imaging for steatosis diagnosis and move directly to fibrosis risk stratification 2. This is because the pretest probability of NAFLD is so high in these populations that confirming steatosis adds little clinical value.

Key Point About Steatosis Detection

• Ultrasound, CT, and MRI can all detect steatosis but none can distinguish simple steatosis from NASH 1, 5
• FibroSure/FibroTest does not diagnose steatosis—it assesses fibrosis 6, 1

Assessing for Advanced Fibrosis (Where FibroSure Might Be Considered)

Once hepatic steatosis is identified, the critical clinical question becomes: Does this patient have advanced fibrosis (F3-F4)? This determines prognosis, need for hepatology referral, and HCC screening.

The Two-Tier Approach (Recommended Algorithm)

Step 1: Use FIB-4 Score First 2, 3, 7

• FIB-4 is calculated from age, AST, ALT, and platelet count
• FIB-4 <1.3 (or <2.0 if age >65): Rules out advanced fibrosis with >90% NPV—no further testing needed, reassess in 2-3 years 2
• FIB-4 >2.67: High risk for advanced fibrosis—refer to hepatology 2
• FIB-4 1.3-2.67 (indeterminate zone): Proceed to Step 2

Step 2: Use Secondary Testing for Indeterminate FIB-4 2, 7 Options include:

• Vibration-controlled transient elastography (VCTE/FibroScan): LSM <8 kPa rules out advanced fibrosis 8
• Proprietary blood tests: Enhanced Liver Fibrosis (ELF) test <9.8, FibroTest <0.48, or FibroMeter <0.45 8
• Magnetic resonance elastography (MRE): Most accurate but expensive, reserved for select cases 1, 8

Why FIB-4 Before FibroSure?

FIB-4 is preferred as the first-line test because it is:

• Free and calculated from routine labs
• Well-validated with AUROC 0.78-0.80 for advanced fibrosis 3, 7
• Correlates with clinical outcomes (liver-related mortality) 2, 7
• More cost-effective than starting with proprietary tests 2, 7

FibroSure/FibroTest performance:

• AUROC 0.85 for advanced fibrosis 5
• Sensitivity 38.9%, specificity 92.7% for advanced fibrosis 1
• Not superior enough to FIB-4 to justify routine first-line use 7
• More expensive and proprietary 2

Common Pitfalls to Avoid

1. Don't order FibroSure to diagnose steatosis—it doesn't measure fat, only fibrosis
2. Don't skip FIB-4 and go straight to expensive tests—the two-tier approach is cost-effective 2, 7
3. Don't assume normal aminotransferases rule out significant disease—up to 50% of patients with NAFLD and even advanced fibrosis have ALT <40 U/L 3
4. Don't use NAFLD Fibrosis Score (NFS) in primary care/endocrinology settings—it overestimates advanced fibrosis in patients with obesity and diabetes 3

When FibroSure Might Be Appropriate

FibroSure/FibroTest can be considered as a secondary test when:

• FIB-4 is in the indeterminate range (1.3-2.67) AND
• Elastography is not available 1, 7
• You need additional risk stratification before hepatology referral

However, elastography (FibroScan) is generally preferred over FibroSure in this scenario because it provides immediate point-of-care results and has comparable accuracy 7, 8.

The Bottom Line

For hepatic steatosis diagnosis: Use ultrasound, not FibroSure 4.

For fibrosis assessment in NAFLD: Start with FIB-4, then use elastography or proprietary tests (including FibroSure) only for indeterminate results 2, 3, 7, 8.

FibroSure is not a first-line test and is never needed just to diagnose steatosis. The most cost-effective and evidence-based approach uses simple, free calculations (FIB-4) before considering proprietary biomarkers.