How To Read And Interpret A Fibroscan Report?

A FibroScan report gives you two numbers that matter most: the liver stiffness measurement (LSM), reported in kilopascals (kPa), and the controlled attenuation parameter (CAP), reported in decibels per meter (dB/m). The kPa value estimates how much scar tissue is in your liver. The CAP value estimates how much fat is in it. Everything else on the page — the IQR, the IQR/median ratio, the number of valid measurements — tells you how much to trust those two numbers.

If you understand those four things, you can read the report the way a hepatologist reads it.

What Is a FibroScan and What Is It Actually Measuring?

A FibroScan is a specialized ultrasound device that measures two different things about your liver at the same time, using two different physical principles.

For stiffness, the machine sends a mechanical pulse through the liver and measures how fast a shear wave travels through the tissue. Scar tissue is denser and less elastic than healthy liver tissue, so waves move through it faster. The machine converts that speed into a stiffness score in kilopascals. Higher kPa means a stiffer liver, which usually means more fibrosis.

For fat, the machine measures how much the ultrasound signal is attenuated (weakened) as it passes through the liver. Fat droplets absorb and scatter sound waves. More fat means more attenuation, which is reported as the CAP score in dB/m.

These are two separate measurements from one test. They are not interchangeable. A person can have a very high CAP (a lot of fat) with a low kPa (little scarring), or the reverse. This is one of the most commonly misunderstood points about FibroScan reports.

The test itself is painless and takes about 10 minutes. You lie on your back with your right arm raised. The technician places the probe between your ribs on the right side. There is no radiation and no needle.

What Do the kPa Numbers on a FibroScan Report Mean?

Liver stiffness in kPa is the core number on the report. Higher values suggest more fibrosis, but the exact cutoff for each fibrosis stage depends on the cause of your liver disease.

Different underlying conditions — hepatitis B, hepatitis C, MASLD (metabolic dysfunction-associated steatotic liver disease), alcohol-related liver disease — produce different stiffness values for the same amount of scarring. That is why the same kPa reading can mean different things for different patients.

That said, there are general ranges that clinicians use as a rough guide:

• Under about 7 kPa — usually considered normal or minimal fibrosis in most conditions. Many clinicians treat this as reassuring.
• Roughly 7 to 10 kPa — often suggests mild to moderate fibrosis. This is a gray zone where other tests may help clarify the picture.
• Roughly 10 to 14 kPa — often suggests significant fibrosis. Many clinicians would consider this a level worth closer monitoring.
• Above roughly 14 kPa — raises concern for advanced fibrosis or cirrhosis, though the exact threshold varies by disease and by the specific cutoff validated for that condition.

These ranges are approximate. Your hepatologist will interpret your number in the context of your specific diagnosis, your other test results, and your history. Do not treat any single kPa value as a diagnosis on its own.

One important caveat: liver stiffness is not only affected by scar tissue. Active inflammation, congestion from heart failure, and even recent meals can push the number up. That is why most centers ask you to fast for at least three hours before the test.

What Does the CAP Score Tell You About Liver Fat?

The CAP score estimates steatosis — the amount of fat in your liver. It is reported in dB/m, and higher values suggest more fat.

Rough general ranges that appear in the clinical literature:

• Under about 240 dB/m — usually considered to indicate little or no significant steatosis.
• Roughly 240 to 280 dB/m — often suggests mild steatosis.
• Roughly 280 to 300 dB/m — often suggests moderate steatosis.
• Above about 300 dB/m — often suggests severe steatosis.

These cutoffs are not universal. Different studies and different device versions have proposed slightly different thresholds. The CAP is also less reliable in people with very high BMI, because the chest wall thickness affects how well the signal reaches the liver.

An important limitation: CAP cannot tell you whether the fat is causing inflammation. Fat alone (simple steatosis) and fat with inflammation (steatohepatitis) can produce similar CAP scores. That distinction matters for prognosis, and CAP alone cannot make it.

What Do IQR and IQR/Median Ratio Mean on the Report?

These two values are reliability indicators. They tell you how consistent the individual measurements were.

The machine takes multiple individual stiffness measurements and reports the median as your final kPa. The IQR (interquartile range) is the spread between the 25th and 75th percentile of those measurements. A small IQR means the measurements were consistent. A large IQR means they varied a lot.

The IQR/median ratio is the IQR divided by the median. It is usually expressed as a percentage or a decimal.

A commonly cited rule of thumb: an IQR/median ratio under 30% (or 0.30) is considered a reliable result. Above that, the result may be less trustworthy, and your clinician may want to repeat the test or use another method.

Other reliability markers to look for on the report:

• Number of valid measurements — most guidelines suggest at least 10 valid measurements are needed for a reliable result.
• Success rate — the percentage of attempts that produced a valid measurement. Higher is better.
• Probe type — the M probe is standard for most adults. The XL probe is used for people with higher BMI, and the values are not directly interchangeable with the M probe.

If the report shows fewer than 10 valid measurements or an IQR/median above 30%, the kPa value should be interpreted with caution. This does not mean the test was useless, but it does mean the number is less precise.

Why Does the FibroScan Report Sometimes Give a Range Instead of a Single Number?

Many modern FibroScan reports do not give a single kPa value with a single interpretation. They give a range, or they show where your value falls on a continuum of risk.

This is because stiffness values overlap between fibrosis stages. A person with stage 2 fibrosis and a person with stage 3 fibrosis can both have a kPa of 11. The test cannot always separate them cleanly.

What the test does well is rule out advanced disease at the low end and rule it in at the high end. The middle zone is where uncertainty lives.

When your value falls in an ambiguous range, your clinician may recommend:

• A second non-invasive test, such as an ELF (Enhanced Liver Fibrosis) blood test or a FIB-4 score
• Repeating the FibroScan after some time to see if the value is changing
• In some cases, a liver biopsy, which remains the only way to definitively stage fibrosis

This is not a sign that something went wrong. It is how non-invasive testing is meant to be used — as a first step, not always as the final answer.

What a FibroScan Cannot Tell You

A FibroScan is a good test, but it has real limits. Knowing them helps you read your report honestly.

It cannot tell you the cause of your liver disease. It measures stiffness and fat, not what is driving them.

It cannot reliably distinguish between adjacent fibrosis stages in the middle of the range. It is better at the extremes than in the middle.

It cannot tell you whether you have inflammation. The kPa value can rise with active inflammation, but the test does not measure inflammation directly.

It cannot replace a biopsy for definitive staging. A biopsy samples a small piece of liver and can be examined under a microscope. FibroScan gives you a whole-liver estimate, but with less detail.

It is also less accurate in certain situations: acute hepatitis, congestive heart failure, extrahepatic cholestasis, and very high BMI can all affect the reading. Your clinician should know about these conditions before interpreting your result.

How Does FibroScan Compare to Other Liver Tests?

FibroScan is one of several non-invasive tools for assessing liver fibrosis. It is not the only option, and it is not always the best one for every patient.

No single test is perfect. Many clinicians use a combination — for example, a FIB-4 first, then a FibroScan if the FIB-4 is elevated. This stepwise approach is common in hepatology and is supported by several professional guidelines.

What Should You Do After Reading Your Report?

Your FibroScan report is a tool for your clinician, not a diagnosis you should act on alone. The kPa and CAP values need to be interpreted in the context of your medical history, your other test results, and the specific condition being evaluated.

If your kPa is low and your CAP is low, that is generally reassuring. If either number is elevated, the next step is a conversation with your doctor about what it means for you specifically.

One practical point: bring the actual report to your appointment, not just the summary your doctor may have received. The reliability indicators (IQR, number of measurements, probe type) matter for interpretation, and they are not always included in a brief summary.

If your result falls in a gray zone, ask your clinician what the plan is. A single number rarely changes management on its own. Trends over time, combined with other clinical information, are usually more useful than any one reading.