What is FIB-4?
Fatty liver is present in one in four adults, and in most it stays at fat. In some the liver becomes inflamed over the years and forms scars, fibrosis, and that is the step that matters: a liver with fat recovers completely, a liver with many scars does not. The problem is that you do not see that in ALT and gamma-GT; those say the liver is under strain, not how much scar already lies there. FIB-4 fills that gap with four numbers you already have. Your age, because scars take years. Your AST and ALT, because a liver forming scars releases proportionally more AST. And your platelets, because a liver with many scars lets the blood from the gut through less well, so the spleen swells and traps platelets. Age times AST, divided by platelets times the square root of ALT, and the pattern that does not stand out in the single values becomes a number. The score is built to rule something out, not to prove something. Below 1.30 advanced scarring is unlikely, and the score is good at that. Above 3.25 it is likely enough to image the liver, with an elastography that measures the stiffness. In between the score deliberately says nothing, and that is not a shortcoming but the reason there are three bands.
Why is FIB-4 relevant?
FIB-4 is the score that turns fatty liver into an answerable question. Anyone with a slightly raised ALT and belly fat really wants to know only one thing: is this still fat, or are there scars already. A FIB-4 below 1.30 says it is almost certainly still fat, and fat disappears with weight loss, less sugar and exercise. That is the outcome the score was made for, and in most people with fatty liver it is the outcome. The second reason is that the score is free and already sits in your result. Your age, AST, ALT and platelets are in every ordinary panel, and the calculation takes ten seconds. Anyone who has their liver values measured yearly can calculate the score yearly and see whether it stays stable, which is the intention, or rises, which raises the question about the liver sooner. The third reason is that you have to know what the score is not. Your age is in the numerator, so the score rises with the years without anything changing in your liver; two people with the same blood get a different result at forty and at seventy, and above 65 the lower cut-off therefore sits higher in practice. Platelets fall through very different things than the liver too, and an AST that shoots up after hard training lifts the score with it. So a high score is a pattern to look further at, not a diagnosis.
FIB-4 decision limits
What counts beside the number:
- Your age, because it is in the numerator and lifts the score without your liver changing
- Your platelets separately, because a fall for another reason lifts the score too
- AST and ALT separately, and whether you trained hard or drank before the draw
- Whether the four numbers come from the same draw
- The trend over the years, because a stable score says more than one result
- With a high score: an elastography, which measures the stiffness of the liver directly
These are decision limits and not normal values: the score sorts by how likely advanced scarring is, and is built to rule it out, not to prove it. Because your age is in the numerator, the score rises with the years, and above 65 the lower cut-off sits higher in practice. Not every lab prints the score; you can calculate it yourself from four numbers from the same draw.
FIB-4 = age × AST (U/l) / (platelets (×10⁹/l) × √ALT (U/l))
McPherson et al., simple non-invasive fibrosis scoring systems can reliably exclude advanced fibrosis in non-alcoholic fatty liver disease, GutFour numbers you already have: age times AST, divided by platelets times the square root of ALT. Nothing extra is drawn for it. Your age is in the numerator, so the score rises with the years even if your blood stays the same.
( × ) ÷ ( × √) =
What Dutch labs actually use
0 – 1.3score
At Unilabs this is normal.
every lab calls 0 – 1.3 score normal. Outside that range every lab calls it abnormal.
Every age, per lab
| Laboratory | Group | Reference range |
|---|---|---|
| Unilabs(Saltro, Medlon, SHO, Atalmedial)2026 | Volwassene | 0 - 1.30 score |
Each band as the lab publishes it, retrieved in 2026, unless marked otherwise.
FIB-4 high or low: what it means
A low FIB-4, below 1.30, means advanced scarring is unlikely. That is the outcome the score was made for, and with an ordinary liver picture at a younger age it is the outcome you expect. If you have fatty liver, this is the moment to clear the fat with lifestyle, before the score ever rises. A high FIB-4, above 3.25, means the four numbers together form a pattern that fits scarring, and then the liver should be imaged with an elastography. It does not mean the diagnosis is established. Look first back at the four numbers separately: an AST that shot up after training, platelets that are low for another reason, or simply being a year older, can lift the score without the liver having changed. Usually it is the first and rarely the last: getting older, fewer platelets, a shift between AST and ALT, and rarely real scarring. In between, from 1.30 to 3.25, the score deliberately says nothing. The question is then answered with an elastography or with a second score, and with the trend: a score that stays the same year on year is more reassuring than a score that rises. What you do about it: with fatty liver and a low score this is the moment for weight loss, less sugar and alcohol, and exercise, because fat is reversible and scars much less so. With a high or rising score the liver should be imaged. Always calculate the score from four numbers from the same draw, and have blood drawn on a rest day, at least two days after hard exertion.
What lowers it
A liver without scars, and in most people that is the outcome.
| Cause | How often |
|---|---|
| An ordinary liver picture at a young ageA normal AST and ALT, normal platelets and an age under fifty give a low score; that is the outcome the score was made for | Often |
What raises it
One of the four numbers lifting the score, and rarely all four at once.
| Cause | How often |
|---|---|
| Getting olderYour age is in the numerator, so the score rises with the years without your liver changing; above 65 the lower cut-off sits higher in practice | Often |
| Fewer plateletsPlatelets are in the denominator and also fall through a viral infection, medicines or a clotting problem; a fall that has nothing to do with the liver still lifts the score | Sometimes |
| A shift between AST and ALTAn AST that shoots up after hard training or rises more than ALT through alcohol lifts the score; drawing on a rest day prevents the first | Sometimes |
| Scarring in the liverThe reason the score looks for: a liver that has formed scars through years of fat or alcohol, with more AST and fewer platelets; an elastography measures it | Rare |
How does a FIB-4 blood test work?
- Referral
- Not needed. The score is a calculation from your age, AST, ALT and platelets, which are all in the ordinary panel you can have measured yourself.
- Fasting
- Not needed. None of the four numbers moves with food.
- When
- On a rest day, at least two days after hard exertion, because an AST that shoots up after training lifts the score.
- The result
- One score without a unit, calculated from four numbers from the same draw: age times AST, divided by platelets times the square root of ALT. Not every lab prints it; you can calculate it yourself.
- Repeating
- Yearly with fatty liver or a liver that stays under strain, from the same draw as the liver values; a score that stays the same is the intention.
- Which test
- FIB-4 is in the comprehensive test (€229) and in .
- Where to draw
- You can draw at 250+ locations near you, no referral needed. See the locations
Frequently asked questions
What is the FIB-4?
A score that estimates how likely it is that your liver has scars, calculated from four numbers you already have: your age, your AST, your ALT and your platelets. No extra tube is involved. The score sorts into likelihoods and establishes nothing; it is built to rule out advanced scarring, and it is good at that.
What does a low FIB-4 mean?
That advanced scarring is unlikely, and that is the outcome the score was made for. Below 1.30 your liver is almost certainly not scarred. If you have fatty liver, this is the moment to clear the fat with weight loss, less sugar and exercise, because fat is reversible and scars much less so.
Does a high FIB-4 mean I have liver fibrosis?
No. Above 3.25 the four numbers together form a pattern that fits scarring, and then the liver should be imaged with an elastography, which measures the stiffness. But the score is built to rule out and answers the reverse question far less sharply. Look first back at the four numbers separately: getting older, low platelets for another reason and an AST after training lift the score without the liver having changed.
What does a score between 1.30 and 3.25 mean?
That the score deliberately says nothing decisive: the four numbers together neither rule out advanced scarring nor point clearly at it. That is the most honest outcome of the three, and the reason there are three bands instead of two. The question is then answered with an elastography, a second score, or the trend over the years.
Why does my score rise while my liver values stayed the same?
Through your age or your platelets. Your age is in the numerator, so the score rises with the years without anything changing in your blood, and above 65 the lower cut-off therefore sits higher in practice. Platelets are in the denominator, so a fall that has nothing to do with your liver, through a virus or a medicine, still lifts the result.
Why are exactly these four numbers in the score?
Because together they form the pattern of a liver with scars. Scars take years, hence the age. A liver forming scars releases proportionally more AST than ALT. And a scarred liver lets the blood from the gut through less well, so the spleen swells and traps platelets. Each number on its own does not stand out; together it becomes a score.
Can I calculate FIB-4 myself?
Yes: your age times your AST, divided by your platelets times the square root of your ALT, with AST and ALT in U/L and platelets in ×10⁹/L. Use four numbers from the same draw, taken on a rest day, because an AST that shoots up after training lifts the score. Calculate it yearly if your liver stays under strain; a score that stays the same is the intention.
What was the score developed for?
To estimate in people with a liver disease, without a biopsy, whether there are advanced scars, first in viral hepatitis and later in fatty liver, where it is now used most. In fatty liver the score is the first step: low means lifestyle is the treatment, high means the liver needs imaging.
Which tests include FIB-4?
FIB-4 is in the comprehensive test (€229) and in .
Related biomarkers
Read on
Sources
- 1.Unilabs, determination guide: FIB-4 score. 2026. bepalingenklapper.nl
- 2.Certe, determination guide: FIB4 index. 2026. bepalingenwijzer.certe.nl
- 3.McPherson et al., simple non-invasive fibrosis scoring systems can reliably exclude advanced fibrosis in non-alcoholic fatty liver disease, Gut. 2010. pubmed.ncbi.nlm.nih.gov
- 4.Sterling et al., development of a simple noninvasive index to predict significant fibrosis in HIV/HCV coinfection, Hepatology. 2006. pubmed.ncbi.nlm.nih.gov
Educational information only, not medical advice. Consult a healthcare professional for clinical decisions.
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