AI Summary The FAST score combines FibroScan liver stiffness, FibroScan liver fat (CAP), and an AST blood test to estimate the risk of MASH with significant fibrosis in people with fatty liver disease. A score below 0.35 is low risk, 0.35 to 0.67 is intermediate, and above 0.67 is high. It avoids a liver biopsy and can be repeated. It estimates risk only, so your doctor decides on follow-up and treatment.
Source: www.liverdirectory.com
Medically Reviewed.
The FAST score, short for FibroScan-AST score, combines three numbers into one risk estimate: liver stiffness and liver fat from a FibroScan, plus an AST blood test. It is used in people who have fatty liver disease.
It estimates how likely you are to have metabolic dysfunction-associated steatohepatitis (MASH) with significant fibrosis, without a liver biopsy. It is a risk estimate, not a diagnosis, and your care team reads it with your other results.
Liver Health AI Assistant
Ask Aimy
Aimy answers from LiverDirectory’s reviewed health information — helping patients make sense of liver-health terms, prepare for specialist visits, and explore what to look up next.
FIBROSCAN-AST SCORE EXPLAINED
The FAST score (FibroScan-AST score) is a calculation that estimates the chance that a person with fatty liver disease has MASH with significant fibrosis.
MASH (metabolic dysfunction-associated steatohepatitis, formerly called NASH) is a more serious form of fatty liver disease. In MASH, fat in the liver comes with inflammation and liver damage. Over time, it can lead to fibrosis (scarring), cirrhosis, or liver failure if it goes untreated.
The FAST score helps your care team find people at higher risk early, so follow-up and treatment can start in time. Unlike a liver biopsy, it needs no procedure on the liver. It uses a FibroScan and a blood test, so it is safe, convenient, and repeatable.
The score does not diagnose MASH, and it does not replace your doctor's judgment. Think of it as a guide to how closely your liver needs to be watched.
FATTY LIVER RISK MONITORING
Your doctor may suggest a FAST score if one of these situations applies to you.
Obesity, type 2 diabetes, and high cholesterol raise the chance of fatty liver disease. If you have one of them, your doctor may want to know whether your liver is at risk of more serious damage.
The FAST score estimates the likelihood of MASH with fibrosis without taking a sample of liver tissue. That makes it a practical first step.
Some fatty liver disease stays stable, and some gets worse. The score helps identify people at risk of advanced fibrosis or MASH early, so care can start on time.
Your doctor may repeat the score to see how your liver responds to lifestyle changes or medical treatment aimed at liver fat and inflammation.
FIBROSCAN AND AST INPUTS
The FAST score combines three measurements. A calculator or the FibroScan software does the math, so you do not need to work it out yourself.
A FibroScan sends a gentle pulse through the liver and measures how fast it travels. A stiffer liver usually means more scarring. Stiffness is reported in kilopascals (kPa).
The same FibroScan exam measures how much the ultrasound beam weakens as it passes through liver fat. More fat gives a higher CAP, reported in decibels per meter (dB/m).
AST is a liver enzyme measured in a blood test. It can rise when the liver is inflamed or injured, so it adds a sign of liver injury to the two scan measurements.
The three values go into a published equation that gives one number between 0 and 1. A higher number means a higher estimated risk.
LOW, INTERMEDIATE, HIGH RANGES
Your score falls into one of three risk groups. Each group suggests a different level of follow-up.
Estimated risk of MASH with significant fibrosis in a person with fatty liver disease.
Low: below 0.35 | Intermediate: 0.35 to 0.67 | High: above 0.67
Below 0.35 (low risk): MASH with significant fibrosis is unlikely. Routine monitoring and lifestyle measures are usually enough.
0.35 to 0.67 (intermediate risk): MASH with fibrosis is possible. Closer monitoring and more evaluation may be recommended, such as more imaging, lab tests, or lifestyle changes.
Above 0.67 (high risk): MASH with significant fibrosis is likely. Evaluation by a liver specialist and possible treatment are advised.
A high score does not confirm MASH, and a low score does not rule out every problem. Your doctor reads it alongside your blood tests, imaging, and health history.
FIBROSIS TEST COMPARISON
No single test tells the whole story. Doctors often use these tests together.
A FibroScan gives separate stiffness and CAP numbers. The FAST score adds the AST blood result and turns all three into one risk estimate for MASH with significant fibrosis.
Blood-only scores, such as the FIB-3 score, use lab values and age. They need no scan. The FAST score needs a FibroScan as well, so it draws on direct measures of liver stiffness and fat.
A liver biopsy examines a tissue sample under a microscope and is the most precise way to confirm the stage of fibrosis. The FAST score carries no procedure risk, so it can help decide whether a biopsy is needed.
FOLLOW-UP AFTER YOUR SCORE
Your risk of MASH with significant fibrosis is low. Your doctor will likely suggest routine monitoring and lifestyle measures. Keep your follow-up visits, since fatty liver disease can change over time.
Ask what your score means for you, when to repeat it, and whether you need more tests. Bring a list of your medicines and your other test results. If you want a specialist's opinion, you can search for a liver specialist near you.
Your doctor may order more imaging or lab tests, or refer you to a liver specialist. Treatment for MASH aims to reduce liver fat and inflammation. Medicines are usually used together with a balanced diet, exercise, weight management, and limiting alcohol.
Food is part of care for fatty liver disease. Your doctor may advise a balanced diet, exercise, weight management, and limiting alcohol alongside any treatment. Our liver-friendly diet guides can help you plan meals.
Explore Liver DietThe Amsety Bar is a nutrition bar made for people with liver conditions. It is low in sodium, gluten-free, dairy-free, and free of refined sugars, colors, and preservatives. It contains the Super 16 Vitamin & Mineral Mix and can serve as a snack or meal replacement.
Shop Amsety Bars
COMMON QUESTIONS
The FAST score is a FibroScan-AST score. It estimates the risk that a person with fatty liver disease has MASH with significant fibrosis. It combines three measurements: liver stiffness and liver fat (CAP) from a FibroScan, and AST from a blood test. A calculator or the FibroScan software turns them into one number between 0 and 1. A higher number means a higher estimated risk. The score is a guide to how closely your liver needs to be watched. It does not diagnose MASH.
A FAST score below 0.35 is the best result. It means low risk. A score from 0.35 to 0.67 is intermediate risk, and a score above 0.67 is high risk. With a low score, MASH with significant fibrosis is unlikely, and routine monitoring and lifestyle measures are usually enough. With an intermediate score, your doctor may suggest closer monitoring and more evaluation, such as more imaging or lab tests. With a high score, evaluation by a liver specialist and possible treatment are advised.
No. A high FAST score does not confirm MASH. It estimates risk only. A score above 0.67 makes MASH with significant fibrosis likely, so your doctor may suggest a visit with a liver specialist or more tests to confirm it. A liver biopsy is the most precise way to confirm the stage of fibrosis. Your doctor reads the score alongside your blood tests, imaging, and health history. A low score also does not rule out every liver problem.
No. The score itself needs no procedure on the liver. It uses FibroScan measurements and a blood test. A FibroScan works like an ultrasound. You lie on your back while a small probe rests over your liver area. The exam is painless and takes about 5 to 10 minutes. It is usually done in a doctor's office or hospital clinic. The blood test is a standard blood draw. Because the score is safe, it can be repeated over time.
Your doctor decides how often, based on your score and health history. Doctors can use the score to follow how your liver responds to lifestyle changes or medical treatment, so repeat testing is common. Because it needs no biopsy, it is easy to repeat. Ask your doctor when to repeat it, and keep your follow-up visits, since fatty liver disease can change over time.
Medical disclaimer: LiverDirectory provides educational information and a directory of providers. It does not provide medical advice, diagnosis, or treatment. Always consult a licensed physician regarding any medical condition.
