Your FibroScan report has two main numbers: one estimates liver fat, and the other measures liver stiffness. Stiffness helps assess fibrosis, the medical word for scarring. Having FibroScan results explained starts with keeping those measurements separate. A high fat reading doesn't automatically mean advanced scarring.
Blood tests, measurement quality and sometimes a biopsy, a small tissue sample, complete the picture. A clinician reads each result against the device's and lab's reference.
FibroScan results explained: CAP score and liver fat
FibroScan uses sound waves to assess the liver. CAP, short for controlled attenuation parameter, estimates fat from how much the ultrasound signal weakens. It's reported in dB/m, decibels per meter, a unit of sound weakening. It isn't a percentage of liver fat.
Karlas and colleagues' 2017 Journal of Hepatology analysis combined individual results from 2,735 people with several liver diseases. Its abstract reports these two cutoffs using the standard M probe, the scanner's measuring attachment:
| CAP cutoff in that analysis | What it helped distinguish |
|---|---|
| 248 dB/m | At least mild fat on biopsy (any grade above S0; S0 means no significant fat) |
| 268 dB/m | Fat grades above S1, meaning more than mild fat on biopsy |
These aren't universal boundaries. Body size, diabetes and the cause of liver disease affected CAP. A small change between scans doesn't necessarily mean the amount of fat changed by the same proportion.
Biopsy fibrosis stages F0–F4
A biopsy shows the pattern of scar tissue directly. The fatty-liver staging system, described in Myers' 2010 multicenter study, uses these stages:
| Stage | Plain meaning |
|---|---|
| F0 | No scarring |
| F1 | Local scarring around small vessels or areas where larger vessels enter |
| F2 | Scarring in both of those locations |
| F3 | Bridging: bands of scar tissue joining areas |
| F4 | Cirrhosis: extensive scarring that changes liver structure |
The 2023 naming consensus introduced MASLD, liver fat linked to metabolic risks such as high blood sugar. MASH is its inflammatory form, with liver-cell injury. These replace the older names NAFLD and NASH.
In ESSENCE, reported by Sanyal in NEJM in 2025, the first 800 participants had MASH and F2–F3 scarring. In that trial at 72 weeks, scarring improved without worse MASH in 36.8% on semaglutide versus 22.4% on placebo, an inactive comparison treatment. MASH cleared without worse scarring in 62.9% versus 34.3%.
Those percentages count people meeting biopsy criteria; they aren't changes in CAP. The ESSENCE trial guide and semaglutide for fatty liver explain the treatment evidence.
FIB-4 score meaning: age and three blood results
FIB-4 estimates the likelihood of advanced scarring using age, AST and ALT, enzymes measured in blood, and platelets, cells involved in clotting. Sterling's 2006 Hepatology paper developed it in people with both HIV and hepatitis C, two viral infections. A FIB-4 of 2 doesn't mean stage F2.
The AASLD 2023 practice guidance sets out a fatty-liver assessment pathway:
| FIB-4 result | Meaning in that pathway |
|---|---|
| Below 1.3 | Lower likelihood of advanced scarring; periodic reassessment |
| 1.3–2.67 | Further assessment, usually a stiffness scan or another blood test |
| Above 2.67 | Higher concern; specialist assessment considered |
Age changes the interpretation. Over age 65, the guidance uses a cutoff above 2.0 for further assessment. Accuracy is lower below age 35. Acute illness can distort the score.
A lab's “normal” ALT range also varies. Normal enzymes can occur alongside advanced scarring, so they don't settle the question alone.
Liver stiffness kPa: why the bands aren't biopsy stages
Stiffness is reported in kPa, or kilopascals, the unit used for this measurement.
In the same AASLD pathway, stiffness below 8 kPa helps rule out advanced scarring after FIB-4. Between 8 and 12 kPa may indicate fatty-liver inflammation with scarring. Above 12 kPa raises concern for advanced scarring, but isn't a diagnosis by itself.
Inflammation and blood backing up into the liver can also raise stiffness. As of October 1, 2026, the day this article was written, an August 3 records study in npj Gut and Liver reported lower stiffness after semaglutide use. Its authors stress that stiffness isn't identical to biopsy-confirmed scarring. The study was observational: it tracked care rather than randomly assigning treatment.
In SYNERGY-NASH, Loomba's 2024 NEJM trial studied 190 adults with MASH and F2–F3 scarring. In that trial at 52 weeks, at least one-stage biopsy improvement without worse MASH occurred in 55%, 51% and 51% across tirzepatide groups, versus 30% on placebo. That doesn't translate into a particular kPa drop. Tirzepatide for fatty liver covers the medication question.
The quality figures beside the result
Reports may list the number of valid readings, their median, or middle value, and IQR/median. IQR means interquartile range: the spread of the middle half of readings. The ratio shows how scattered they are relative to the middle value.
Boursier's 2013 Hepatology study tested the traditional criteria of at least 10 valid readings and IQR/median no higher than 30%. Reading count alone didn't establish accuracy. Results were poorly reliable when IQR/median exceeded 30% and stiffness was at least 7.1 kPa.
That 30% describes measurement spread. It doesn't mean 30% liver fat.
MRI-PDFF liver fat: percentages and percentage points
MRI-PDFF, magnetic resonance imaging proton density fat fraction, estimates the share of the scan's signal coming from fat. It measures fat, not scarring. AASLD lists 5% or more as a threshold for identifying liver fat with this method.
As of October 1, 2026, the day this article was written, Novo Nordisk's October 1 STEP UP announcement reported MRI liver fat falling from 8.8% to 3.1% over 72 weeks in pooled semaglutide groups. That's a 5.7-percentage-point drop: subtracting one percentage from another. This exploratory conference analysis involved a 55-person subgroup and wasn't a planned main trial outcome.
In Stanley's 2019 Lancet HIV trial, 61 adults with HIV and fatty liver were studied for 12 months. Researchers used magnetic resonance spectroscopy, a related technique that separates fat and water signals. In that trial, tesamorelin's estimated treatment effect versus placebo was a 4.1-percentage-point greater fat reduction and a 37% relative reduction. Relative change compares the drop with the starting amount.
Neither figure means 37 percentage points of fat disappeared. The population and measurement matter; tesamorelin for fatty liver explains the study's limits.
How the numbers fit a provider conversation
A repeat result is most useful with its date, method, units and quality information. Fat, inflammation and scarring can change differently. They answer separate questions.
As of October 1, 2026, the day this article was written, the Wegovy label, marked “Revised: 6/2026”, lists adults with MASH and F2–F3 scarring without cirrhosis. The FDA's indication letter names this same group. A CAP score alone doesn't establish that diagnosis.
Through Promise, semaglutide, tirzepatide and tesamorelin are dispensed as compounded medications, prepared by a pharmacy for a prescription. This is different from an FDA-approved product: the formulations offered here are not FDA-approved. The FDA explains that compounded drugs aren't reviewed for safety, effectiveness or quality before marketing. Trial results don't establish identical outcomes for these preparations.
A licensed provider may still prescribe — that decision is between you and your doctor. At Promise, a licensed provider reviews every request, and not everyone qualifies.
