FIB-4 for Primary Care: When to Refer to Hepatology

July 20, 2026

FIB-4 was built specifically to be usable in primary care, since it only requires labs most patients already have on file. This guide covers how AASLD practice guidance frames the referral decision once a score comes back from the FIB-4 calculator.

Step 1 — Identify Who Should Be Screened

FIB-4 is most useful as a first-line screen in patients with metabolic risk factors for MASLD (obesity, type 2 diabetes, metabolic syndrome) or known chronic liver disease risk (hepatitis B/C, heavy alcohol use), rather than as a universal screening test for the general population without risk factors.

Step 2 — Run the Score and Apply the Right Cutoff

Enter age, AST, ALT, and platelet count into the FIB-4 calculator. Remember the age-adjusted cutoff — patients 65 and older use a low-risk threshold of below 2.00 rather than below 1.30, since age inflates the score independent of actual fibrosis.

Step 3 — Low Risk: Manage in Primary Care

A FIB-4 below the applicable low-risk cutoff has a negative predictive value exceeding 90% for advanced fibrosis, per AASLD guidance — this is reassuring enough that these patients are typically managed in primary care with routine monitoring (repeat FIB-4 periodically, usually every 1-3 years depending on risk factors) rather than an immediate specialist referral.

Step 4 — Indeterminate: Add a Second Non-Invasive Test Before Deciding

A FIB-4 in the indeterminate zone (1.30-2.67, or 2.00-2.67 in patients 65+) doesn’t resolve cleanly to “refer” or “don’t refer” on its own. AASLD guidance describes using a second non-invasive test — most commonly elastography (FibroScan) — to clarify risk before committing to a referral decision. A low elastography result after an indeterminate FIB-4 often allows continued primary care management; an elevated one supports moving to Step 5. See the liver fibrosis staging glossary for what elastography actually measures.

Step 5 — High Risk or Confirmed on Second Test: Refer to Hepatology

A FIB-4 above 2.67 (or an indeterminate score confirmed by elevated elastography) is the threshold where AASLD practice guidance points toward hepatology referral for further evaluation — which may include additional imaging, closer monitoring, or consideration of liver biopsy in select cases. This is also the point where FIB-4’s weaker positive predictive value (around 65% even at stricter cutoffs) matters most: a high score is a strong signal to involve a specialist, not a confirmed cirrhosis diagnosis on its own.

Step 6 — Don’t Skip Reassessing Confounders First

Before referring on an indeterminate or high score, rule out non-fibrosis explanations for the underlying labs — recent heavy exercise or muscle injury can elevate AST independent of the liver, and certain medications (including some statins) have been shown to shift FIB-4 and elastography results for a given patient. See common FIB-4 calculation mistakes for the specific confounders worth checking before finalizing a referral decision.

Quick-Reference Pathway

FIB-4 Result	Typical Next Step
Below low-risk cutoff	Manage in primary care; periodic repeat FIB-4
Indeterminate	Add elastography or another non-invasive test before deciding
Above 2.67 (or indeterminate + elevated second test)	Refer to hepatology

Bottom Line

FIB-4 is designed to triage, not diagnose — a low score keeps most patients comfortably in primary care, an indeterminate score calls for a second non-invasive test rather than an immediate referral, and a high or confirmed score is the clear signal to involve hepatology. Use the FIB-4 calculator as the first step in this pathway, not the last one.