Metabolic health
Fatty Liver Blood Test Normal Range: The Numbers, Read Honestly
Reviewed by a qualified clinician · analysed at UKAS-accredited UK labs (ISO 15189)
Last reviewed August 20266 min read
Every Helvy guide is written by our health editors, then checked by a qualified clinician before it goes live and re-checked as the science moves. We name clinical roles, not individuals, until each reviewer has agreed to be credited publicly. This is wellness guidance to help you understand your own data, not a diagnosis.
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UK labs read ALT against roughly 10 to 60 IU/L in men and 10 to 40 in women, and AST under 50 and 35. Fatty liver often sits inside those ranges. NICE notes that more than 80% of people with the condition have normal routine liver blood tests, so normal does not rule it out.
Not sure which markers you need? Build your test →You have a liver result in front of you. ALT 44. Nothing flagged. Someone has mentioned fatty liver, so you want to know where 44 sits and what it means.
Here are the numbers. Then the awkward part, which is that the numbers answer a narrower question than most people expect.
1. What is the normal range on a fatty liver blood test?
There is no single test called the fatty liver test. What gets run is a liver panel, and the two enzymes people ask about are ALT and AST. Both are proteins that live inside liver cells. When those cells are irritated, some enzyme leaks into the blood.
Ranges differ from lab to lab. North Bristol NHS Trust publishes the figures below.
| Marker | Men | Women |
|---|---|---|
| ALT | 10 to 60 IU/L | 10 to 40 IU/L |
| AST | under 50 U/L | under 35 U/L |
Other trusts word it differently. Royal Cornwall Hospitals uses a single adult ALT range of 0 to 55 U/L for both sexes. So an ALT of 44 is normal in Cornwall and normal for a man in Bristol, but above range for a woman there. Always read your number against the range printed on your own report. Our guide to how UK reference ranges are built explains why they move around like this.
2. Can you have fatty liver with normal blood tests?
Yes, and it is the usual case rather than the exception. This is the single most useful thing to know before you read your result.
“More than 80% of patients with MASLD have normal routine liver blood tests.”
— NICE guideline NG49
MASLD is the current name for what most people still call non-alcoholic fatty liver disease. It stands for metabolic dysfunction-associated steatotic liver disease. The name changed in 2023. The condition did not.
The reason normal is so common is simple. Enzymes leak when liver cells are actively irritated. Fat can sit in the liver quietly for years without that happening. So a normal ALT tells you your liver cells are not leaking much today. It does not tell you what is stored inside them.
3. What ALT level suggests fatty liver?
There is no cut-off that settles it. No number on a liver panel diagnoses fatty liver, and no number rules it out. Imaging does that job, usually an ultrasound scan.
What the enzymes give you is a pattern worth taking to a GP. Three things stand out.
- A mild, persistent rise. Fatty liver typically nudges ALT to somewhere between one and three times the upper limit, not ten times it.
- ALT above AST. Early on, ALT is usually the higher of the two.
- It stays up. One raised reading after a hard gym session or a heavy weekend means little. Two, months apart, means more.
Enzymes also rise for reasons that have nothing to do with fat. Intense exercise, recent illness, some medicines and alcohol all do it. If you are testing privately, our guide on alcohol before a blood test covers how long to leave before the sample.
4. What does the AST:ALT ratio tell you?
Divide your AST by your ALT. The number that comes out is a rough pointer to where the strain is coming from. It is a clue, not a verdict.
| Ratio | What it points at |
|---|---|
| Below 1 | The usual pattern in early fatty liver. |
| Around 1 or above | Can appear as scarring builds. Worth a GP conversation. |
| Above 2 | Classically points at alcohol rather than fat. |
That above-2 pattern has been described in the liver literature for decades. One published comparison found a mean ratio of 2.54 in people with alcohol-related liver disease.
One caution. A ratio needs both numbers, and plenty of UK liver panels report ALT without AST. If yours does, you cannot calculate it, and there is nothing wrong with your result. Our liver enzyme levels by age guide covers what shifts these numbers decade by decade.
5. Which numbers matter alongside the enzymes?
Fatty liver is a metabolic condition. So the markers that describe your metabolism often say more than the liver enzymes do.
- Triglycerides. The fat your blood carries. High triglycerides and a low HDL travel with fatty liver.
- HbA1c. Your average blood sugar over about three months.
- Waist measurement. Free, and a better predictor than most blood markers.
Read together, those give you the picture the enzymes cannot. If your triglycerides are the part you want to understand, our cholesterol blood test guide breaks down what each lipid number is doing. The metabolic health hub gathers the rest, including insulin resistance, which sits underneath most cases.
There is one more marker you will see mentioned online. GGT is another liver enzyme, and it is sensitive to alcohol. It is not part of a Helvy panel, so if you want it, ask your GP. Our GGT guide explains what it adds.
6. Which blood test reports these markers?
Helvy's Thyroid & Vital Organs panel (£159) reports ALT, ALP and albumin with your full cholesterol breakdown, including triglycerides. It also covers kidney and thyroid markers, because those move for some of the same reasons.
For the blood sugar half of the picture, HbA1c sits in our Advanced Heart Health panel (£159), next to ApoB and hs-CRP.
Two honest limits. We do not carry AST or GGT on any panel, so you cannot calculate an AST:ALT ratio from a Helvy result. And no blood test sees fat inside the liver. That needs a scan. What these markers give you is a baseline you can measure the next six months against, which is exactly what the lower-your-ALT guide is built around.
To choose your own markers, the build-my-test tool walks you through it. For the mechanism behind all of this, read our fuller fatty liver blood test guide.
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Frequently asked questions
What is the normal range for a fatty liver blood test?
There is no separate fatty liver test. The liver panel reports ALT and often AST. North Bristol NHS Trust reads ALT against 10 to 60 IU/L in men and 10 to 40 in women, with AST under 50 and 35. Ranges vary between labs, so use the one on your report.
What ALT level indicates fatty liver?
No single level does. Fatty liver typically produces a mild, persistent rise, somewhere between one and three times the upper limit of the range, with ALT higher than AST. A scan confirms it, not a number. A qualified clinician reads the pattern in context.
Can you have fatty liver with normal liver enzymes?
Yes, and it is common. NICE notes that more than 80% of people with the condition have normal routine liver blood tests. Fat can sit in the liver for years without irritating cells enough to push enzymes up.
What AST:ALT ratio suggests fatty liver?
A ratio below 1 is the usual pattern in early fatty liver. A ratio above 2 classically points at alcohol instead. One published comparison found a mean of 2.54 in alcohol-related liver disease. The ratio is a clue for a clinician, not an answer on its own.
Which liver enzymes are raised with fatty liver?
Usually ALT first, sometimes AST alongside it, and sometimes GGT as well. ALT is the most liver-specific of the three, which is why it is the one most often reported on its own.
Is there a fatty liver blood test chart by number?
No official one exists, and any chart claiming to grade fatty liver by ALT value is inventing thresholds. Enzyme levels track irritation, not how much fat is stored. The two do not line up closely enough to build a chart from.
Related guides
Fatty Liver Blood Test UK
The markers, the mechanism, and when to see your GP.
ALT Blood Test UK
What the single most-reported liver enzyme measures.
How to Lower ALT Levels
What actually moves the number, and over what timescale.
Liver Enzyme Levels by Age UK
How ALT, AST and ALP shift decade by decade.
Liver Function Test UK
Every marker on a standard UK liver panel, explained.
Blood Test Reference Ranges UK
Why normal on a lab report is a population range, not a target.