FibroScan Report Sample: How to Interpret Your Results

A FibroScan report gives you two core numbers: a liver stiffness measurement (LSM) in kilopascals (kPa) and, on most modern machines, a controlled attenuation parameter (CAP) score in decibels per meter (dB/m). The LSM estimates how much scar tissue (fibrosis) your liver has, while the CAP score estimates how much fat (steatosis) is stored there. A healthy liver typically measures around 4 to 5 kPa and has a CAP well below 250 dB/m, but the numbers on your report can be pushed around by factors that have nothing to do with fibrosis or fat, which is why understanding context matters as much as memorizing cutoff charts.

The Two Numbers That Matter Most

When you look at your report, the liver stiffness measurement is the headline figure. A stiffer liver generally means more scarring. In a study of adults without known liver disease, the average liver stiffness was about 4.4 kPa, with values ranging from roughly 2.2 to 6.3 kPa across the group.¹ If your number falls in that neighborhood and you have no other risk factors, your liver is likely in good shape.

The CAP score is the second number. It captures how much of your liver tissue is replaced by fat droplets. The device sends an ultrasound pulse through the liver and measures how much that pulse weakens as it travels, since fat absorbs ultrasound energy. A higher CAP means more fat. In patients with chronic liver conditions, average CAP values were around 227 dB/m with no meaningful fat, climbing to roughly 255 dB/m with mild fat and close to 298 dB/m with moderate-to-severe fat.² Both measurements are taken simultaneously during the same exam, and the report typically shows the median of at least ten valid readings for each.³

Reading the Fibrosis Stage on Your Report

Most reports translate the raw kPa number into a fibrosis stage from F0 to F4. These stages describe a spectrum from a completely normal liver to cirrhosis. A widely used set of cutoffs for patients with fatty liver disease categorizes fibrosis as follows:⁴

F0 (no fibrosis): 1–6 kPa
F1 (mild fibrosis): 6.1–7 kPa
F2 (moderate fibrosis): 7.1–9 kPa
F3 (severe fibrosis): 9.1–10.3 kPa
F4 (cirrhosis): 10.4 kPa and above

These thresholds are not universal. The exact cutoffs your doctor uses can vary depending on the underlying cause of liver disease. Hepatitis C, hepatitis B, and alcohol-related liver disease each have slightly different validated ranges, so a reading of 8 kPa could place you at F2 under one set of guidelines and F1 under another. The staging on your printed report reflects whichever reference your clinic has chosen, and your doctor should be interpreting it in the context of your specific diagnosis.

It is also worth knowing that the boundary between stages is not a hard wall. A reading of 6.9 kPa and one of 7.1 kPa sit on either side of the F1/F2 line, but biologically they describe nearly identical livers. Think of the stages as zones on a gradient rather than distinct categories. What your doctor cares about most is whether you are in a low-risk zone (F0–F1), an intermediate zone where closer monitoring or treatment changes might be warranted (F2), or a high-risk zone (F3–F4) where more aggressive workup is needed.

What the CAP Score Tells You About Liver Fat

The CAP portion of your report grades steatosis from S0 (essentially no excess fat) through S3 (severe fatty infiltration). Rough thresholds vary by study and population, but a commonly cited pattern places the onset of meaningful fat detection somewhere around 240–250 dB/m for S1, with values approaching 300 dB/m or higher pointing toward moderate or severe steatosis.

The CAP score is better at telling you whether fat is present than at telling you exactly how much. One study found that CAP values above 300 dB/m were quite specific for detecting steatosis (correctly ruling it in about 88% of the time) but could not reliably distinguish between mild, moderate, and severe fat grades.⁵ In other words, once your CAP crosses a certain threshold, the device confidently says “yes, there is fat,” but it struggles to say exactly how much. A CAP of 320 and a CAP of 370 both mean fatty liver; the second does not necessarily mean twice as much fat.

Body weight complicates CAP readings. A meta-analysis found that for people with a BMI above 30, the CAP cutoffs needed to detect various fat grades were about 28–31 dB/m higher than for leaner patients.⁶ That is a meaningful gap. If you carry extra weight, a CAP reading that looks alarming by standard cutoffs may partly reflect the physics of the ultrasound passing through more tissue rather than a dramatically fattier liver. Your doctor should factor your body composition into the interpretation.

Quality Indicators You Should Not Ignore

Somewhere on your report, usually near the raw data, you will see a few quality metrics. These tell you and your doctor whether the scan itself was reliable enough to trust.

The most important quality marker for the liver stiffness measurement is the IQR/Med ratio, which stands for interquartile range divided by median. In plain terms, it tells you how consistent the individual readings were. If the machine took ten pulses and some came back at 6 kPa and others at 14 kPa, the spread is wide and the median may not be trustworthy. A ratio below 0.30 (sometimes cited as below 0.10 for stricter reliability) is generally considered acceptable. Research confirms that the reliability of liver stiffness values depends on this ratio.³ If your report shows a high IQR/Med, your doctor may want to repeat the exam or use a different assessment method.

Interestingly, the CAP score does not depend on the IQR/Med ratio in the same way.³ That is a quirk of the physics involved: the stiffness measurement relies on tracking a shear wave through tissue, which is more sensitive to variability in positioning and body habitus, while the CAP is based on how much signal the ultrasound loses over a fixed distance, which tends to be more reproducible. Still, if your overall scan had technical problems (too few valid shots, for example), both numbers should be viewed cautiously.

You will also see the total number of valid measurements and the success rate. The standard protocol requires at least ten valid readings. If the operator struggled to get valid shots and the success rate dips below about 60%, or if fewer than ten valid readings were obtained, the results may be unreliable regardless of what the median value says.

Why You Should Fast Before a FibroScan

If your clinic told you to skip food for two or three hours before the exam, there is a solid reason. Eating triggers increased blood flow through the portal vein into the liver, a process called splanchnic hyperemia. That extra blood flow temporarily swells and stiffens the liver, and the FibroScan dutifully measures the artificially elevated stiffness.

The effect is not trivial. One study measured liver stiffness before and after a standard meal and found that stiffness jumped from an average of about 7.8 kPa fasting to 10.3 kPa after eating.⁷ That kind of increase could bump you from an F1 reading to an F3 reading on paper, a difference large enough to change clinical decisions. Another study in 100 healthy volunteers found that eating created an 11% chance of being incorrectly classified as having significant fibrosis when no fibrosis was actually present.⁸

The post-meal effect appears more pronounced in people who already have chronic liver disease. A separate study found that the stiffness rise 30 minutes after eating was statistically significant in patients with liver disease but not in healthy volunteers.⁹ The CAP score, by contrast, did not change meaningfully after eating in the same study.⁹ So if your liver stiffness number seems unexpectedly high but your CAP looks normal, and you happened to eat beforehand, a non-fasting state is a likely explanation for the stiffness result.

Other Things That Can Inflate Your Stiffness Reading

Eating is the most controllable confounder, but it is not the only one. Active liver inflammation, particularly when liver enzymes (ALT and AST) are elevated, can significantly raise stiffness readings independent of how much scar tissue is actually present. In patients with chronic hepatitis B, elevated ALT has been shown to lead to overestimation of fibrosis stage.¹⁰ If you had your scan during a flare of hepatitis or while your liver enzymes were running high for any reason, your doctor may interpret the result more conservatively or wait for the inflammation to settle before making staging decisions.

Heart failure and liver congestion can also drive stiffness up. When the heart cannot pump blood forward efficiently, back-pressure builds in the hepatic veins, engorging the liver and making it stiffer on the scan. Various conditions including steatosis, hepatitis, and cholestasis (bile-duct obstruction) are recognized confounders of liver stiffness measurement.¹¹ If you have known heart problems, your hepatologist needs to weigh the stiffness result against your cardiac status.

The practical takeaway: a single elevated reading does not automatically mean advanced fibrosis. Your doctor should look at the stiffness number alongside your blood work, imaging, symptoms, and medical history before deciding what stage you are in.

M Probe Versus XL Probe

Your report may note which probe was used. FibroScan machines come with two main probes for adults: the standard M probe and the larger XL probe, designed for people with more body tissue between the skin surface and the liver. The XL probe sends its pulse deeper (measuring at roughly 35–75 mm depth compared to 25–65 mm for the M probe) and uses a slightly lower ultrasound frequency.¹²

The XL probe succeeds far more often in patients where the M probe fails or gives unreliable results. In one study of overweight and obese patients, the XL probe produced reliable readings in 73% of patients compared to only 50% with the M probe.¹³ A separate comparison found that 98% of patients could be measured with the XL probe versus 85% with the M probe.¹⁴

Here is the catch: the XL probe consistently produces lower stiffness readings than the M probe in the same person. Studies report XL values running roughly 1 to 2 kPa lower, with one study finding median liver stiffness of 6.8 kPa with the XL probe versus 7.8 kPa with the M probe in the same patients.¹³ That means the fibrosis cutoffs listed in the previous section may not apply directly to XL-probe readings. Some clinics use adjusted cutoffs for the XL probe, while others note the probe type and interpret accordingly. If your report does not specify which probe was used and you are comparing results across visits or clinics, ask your provider, because switching probes between scans could make it look like your fibrosis improved or worsened when nothing actually changed.

When FibroScan Outperforms Blood Tests, and When It Does Not

Your doctor may also have ordered blood-based fibrosis scores like FIB-4 or APRI. These scores use routine blood work (liver enzymes, platelet count, sometimes albumin and age) to estimate fibrosis without any imaging at all. They are cheap and universally available, but they tend to be less accurate than FibroScan at pinpointing where you sit on the fibrosis spectrum.

In a large hepatitis C cohort, FibroScan’s diagnostic accuracy for detecting significant fibrosis was higher than both APRI and the King’s Fibrosis Score, and similar to FIB-4, though FibroScan edged it out for diagnosing cirrhosis specifically.¹⁵ In fatty liver disease, FibroScan correctly identified advanced fibrosis (F3/F4) in about 46% of patients who actually had it on biopsy, while FIB-4 caught only about 17% and another blood-based score caught about 23%.¹⁶

Those numbers might look modest, and honestly, they are. Even FibroScan misses more than half of advanced fibrosis cases in some populations when you set the cutoffs conservatively. The flip side is that it is much better at ruling out advanced disease: if your FibroScan reading is low, you can be fairly confident that you do not have cirrhosis. Where FibroScan really shines is in its negative predictive value and in tracking changes over time, rather than providing a one-shot definitive diagnosis. Liver biopsy remains the reference standard for fibrosis staging, but it is invasive, painful, and subject to its own sampling errors, which is precisely why FibroScan exists.

For the CAP score specifically, the same fatty liver disease study found that FibroScan’s CAP correctly flagged about 90% of patients with the most severe fat grade. But it also classified about 81% of patients with only mild or moderate fat as having severe steatosis.¹⁶ This confirms the broader pattern: CAP is good at saying “fat is present” but overestimates the grade in a lot of patients.

Tracking Changes Over Time

If you have been diagnosed with chronic liver disease, you may get repeat FibroScan exams every year or two. The idea is straightforward: if treatment is working (whether that is antiviral medication, weight loss, alcohol cessation, or a new drug), your liver should get softer over time, and the kPa number should drop. Research supports using FibroScan longitudinally to track how fibrotic burden changes during antiviral or antifibrotic treatment.¹⁷

That said, small changes between scans are noisy. Normal day-to-day variability, differences in fasting status, mild inflammation, and operator technique can all shift the number by a kilopascal or two. Your doctor should be looking at the trend across multiple readings rather than reacting to a single-visit change. A drop from 12 kPa to 8 kPa over two years of treatment is a clear and meaningful improvement. A shift from 7.2 to 6.8 at your next visit is within the noise range and might not mean anything has changed biologically.

Blood-based fibrosis scores, for comparison, have been found to be only weakly associated with disease progression in fatty liver disease when measured repeatedly over time.¹⁸ FibroScan appears to capture true changes in liver stiffness more sensitively than these scores do, which is another reason doctors prefer it for serial monitoring.

Very High Readings and Portal Hypertension

If your liver stiffness comes back above roughly 20 kPa, your doctor is no longer just staging fibrosis. At those levels, the clinical concern shifts toward portal hypertension, a condition where pressure builds in the vein carrying blood to the liver, sometimes causing serious complications like enlarged veins in the esophagus or fluid in the abdomen. Liver stiffness above 21 kPa, particularly when combined with imaging showing collateral blood vessels, is used to identify clinically significant portal hypertension without needing to measure the pressure directly.¹⁹

This is worth knowing because many patients focus exclusively on the F0–F4 staging and overlook what a very high kPa reading implies beyond the label “F4.” Cirrhosis itself exists on a spectrum, and a stiffness of 11 kPa versus 30 kPa, while both technically F4, carry very different risk profiles. If your reading is in the high range, expect your doctor to order additional tests like an upper endoscopy to check for varices or imaging to evaluate the portal system directly.

FibroScan in Children

Pediatric fatty liver disease is increasingly common, and FibroScan is used in children, though with different reference values. In a study measuring liver stiffness in healthy children aged 3 to 18, the average stiffness across all ages was about 3.8 kPa by transient elastography, with normal upper limits rising gradually from about 4.4 kPa in the youngest group (ages 3–5) to roughly 5.1 kPa in adolescents aged 15–18.²⁰ These are slightly lower than adult reference values, so adult cutoffs should not be applied directly to a child’s report. If your child has had a FibroScan, the pediatric gastroenterologist will use age-appropriate ranges that account for the smaller, softer liver typical of younger patients.

The FibroScan device also comes with a smaller S probe designed for children and very thin adults, which uses a higher ultrasound frequency and measures at a shallower depth. As with the M-versus-XL issue in adults, using the wrong probe for a child’s body size can distort results, so the clinic’s choice of probe matters for accuracy.