GP consultation tool

FIB-4: from score to next step

Assess fibrosis risk, decide when to consider FibroScan or gastroenterology, and prepare a practical management plan.

For adults with suspected MASLD. FIB-4 estimates the likelihood of liver fibrosis using age and blood tests. It helps select the next assessment; it does not diagnose MASLD, MASH or cirrhosis.

Uses Northern/Auckland laboratory age bands, updated 4 August 2026. See thresholds and sources ↓

01 / Blood results

Start with the same blood draw.

Use stable results where possible. The calculation needs AST as well as ALT and platelets.

Age at blood testyearsUse age in whole years.ASTU/LRequest separately if missing from the liver panel.ALTU/LUse the actual value, not a multiple of the upper limit.Platelets×10⁹/LFor 200 ×10⁹/L, enter 200.

FIB-4 = age × AST ÷ (platelets × √ALT)

02 / Clinical context

Check whether the score fits.

Are these stable outpatient results?Clinical settingAny features of advanced liver disease?Concerning: splenomegaly/portal hypertension on USS, unexplained low platelets, low albumin or raised INR. Acute: new/worsening ascites, jaundice with illness, confusion or GI bleeding.Could another condition distort AST or platelets?Examples: muscle injury, haemolysis, haematological disease or medicines affecting platelets.Metabolic risk for future recallOther risks include central obesity, hypertension, high triglycerides or low HDL.Liver enzymes raised for more than six months?

03 / Optional weight goals

Turn a percentage into kilograms.

For MASLD with overweight or obesity, agree a sustainable target and protect muscle mass. Avoid automatic weight-loss advice with frailty, malnutrition or advanced liver disease.

Weight loss is appropriate for this adult after nutritional assessment.Current weight (optional)kg

Alongside fibrosis assessment

Treat metabolic risk at every score.

Agree weight goals

At least 5% sustained loss can reduce liver fat.
7–10% can improve liver inflammation.
At least 10% offers a greater chance of fibrosis improvement.

These are goals for suitable adults with overweight/obesity, not guaranteed outcomes.

Make changes achievable

Build towards more than 150 minutes of moderate activity a week, or 75 minutes vigorous activity, as tolerated. Include resistance activity to preserve muscle.

Use a Mediterranean-style eating pattern: vegetables, wholegrains, legumes, nuts, fish and unsaturated fats. Reduce sugary drinks and ultra-processed foods.

Manage the wider risks

Review HbA1c, blood pressure, lipids, alcohol and medicines. Offer dietitian and weight-management support; consider diabetes/obesity medicines for their indicated use.

Discourage alcohol; advise abstinence with advanced fibrosis or cirrhosis. Investigate alternative liver disease when indicated.

Quick reference

Use the threshold for the setting.

Northern Region / Auckland laboratory FIB-4 bands
Age	Lower result	Next assessment
Under 36	Unreliable: consider another fibrosis assessment if risk is significant.
36–59	Below 1.3	1.3 or above: consider FibroScan and gastroenterology assessment.
60 and over	Below 2.0	2.0 or above: consider FibroScan and gastroenterology assessment.

A score above 2.67 adds concern and supports specialist referral in international guidance. International guidelines often use different age boundaries (under 35 and over 65); this tool uses the local bands above.

When FIB-4 can mislead

Acute illness, acute hepatitis or a recent alcohol-related liver flare can transiently raise the score.
Non-hepatic platelet abnormalities, muscle injury or haemolysis can distort the inputs.
Young age can produce a deceptively low score; older age can increase false positives.
Diabetes and other high-risk settings reduce reassurance from a low result. Normal ALT or ultrasound does not exclude advanced fibrosis.
FIB-4 does not measure liver function or prove a change in fibrosis. A falling score after treatment does not by itself show scar regression.
Known cirrhosis, portal hypertension, low albumin, unexplained high INR or discordant findings need clinical assessment regardless of the score.

Repeat testing and FibroScan

With a low result and reassuring clinical findings, consider FIB-4 again in 1–2 years with prediabetes/type 2 diabetes or multiple metabolic risks, and 2–3 years at lower metabolic risk. Review sooner if the clinical findings or blood trends change. Persistent enzyme elevation for more than six months merits investigation and possible specialist review.

For an elevated score, discuss gastroenterology and FibroScan or another second-stage test. Routine ultrasound and FibroScan answer different questions. A reliable FibroScan stiffness below 8 kPa generally suggests lower risk of advanced fibrosis in MASLD; 8 kPa or above needs further assessment. Interpret stiffness with the scan quality and clinical context.

Sources and calculation

FIB-4 = age (years) × AST (U/L) / [platelets (×10⁹/L) × √ALT (U/L)]. Thresholds use the Northern/Auckland test guide; reassessment and management advice draw on EASL and AASLD guidance.

Sources checked 18 October 2026. Review the clinical findings alongside the result.

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