Liver markers
Normal ALT Levels UK: The Range, and What Yours Means
Reviewed by a qualified clinician · analysed at UKAS-accredited UK labs (ISO 15189)
Last reviewed September 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.
QUICK ANSWER
Most UK labs put the top of the normal ALT range somewhere between 33 and 60 U/L, and many set a lower ceiling for women than for men. ALT is alanine aminotransferase, an enzyme your liver cells hold. Read your figure against the range printed on your own report.
Not sure which markers you need? Build your test →Your result says ALT 38. Nothing is flagged. You search for the normal range anyway, and the first four pages give you four different answers.
They are all telling the truth. There is no single national ALT range in the UK, and that is the first thing worth understanding about your number.
1. What is a normal ALT level in the UK?
It depends on who ran your blood. ALT stands for alanine aminotransferase. It is an enzyme that sits inside liver cells, and a little of it leaks into your blood all the time. The test measures how much is out there.
Here is one real NHS range, published by the Liverpool University Hospitals pathology service:
“MALE: ≤41 U/l ... FEMALE: ≤33 U/l”
— Liverpool University Hospitals NHS Foundation Trust
Other UK laboratories stop lower or carry on higher, and some print one figure for everybody. So an ALT of 45 can be flagged in one city and printed as normal in the next. Our guide to high ALT levels sets several NHS trust ranges side by side, and blood test reference ranges explains why a lab range is a population spread rather than a target.
What does an ALT of 25, 38 or 55 mean?
Most people arrive holding one figure. Here it is, one value at a time, in U/L.
| Your ALT | If you are male | If you are female |
|---|---|---|
| 15 | Well inside every UK range | Well inside every UK range |
| 25 | Inside the range | Inside the range |
| 33 | Inside the range | On the ceiling at some labs |
| 38 | Inside the range at most labs | Over the line at some labs |
| 45 | Flagged at some labs, not others | Flagged at most labs |
| 55 or more | Flagged at most labs | Flagged at most labs |
One caveat covers the table. ALT is read beside your other liver markers, never alone, because the pattern says more than any single line. The liver function test explains what sits alongside it.
2. Why is the ALT ceiling different for men and women?
Because healthy men run higher. Lab ranges are built by measuring a group of people considered healthy and keeping the middle 95% of their results. When that group is split by sex, the male numbers land higher, so the male ceiling does too.
Age barely changes the adult range, which surprises people. It is the pattern of your markers that shifts as the decades pass rather than the range itself. Our guide to liver enzyme levels by age covers what does and does not move.
3. Is a normal ALT the same as a healthy ALT?
Not quite, and this is the part worth reading twice. The ceilings most labs use were set decades ago from populations that quietly included people with liver problems nobody had spotted.
A study of 6,835 first-time blood donors in Annals of Internal Medicine reworked the limits using only the people at lowest risk of liver disease. The figures came out much lower:
“Updated upper limits (for men, ... 30 U/L; for women, ... 19 U/L) were lower than current limits (for men, ... 40 U/L; for women, ... 30 U/L).”
— Prati et al., Annals of Internal Medicine, 2002
The tighter limits caught far more people with liver injury. In that study, sensitivity rose from 55% to 76.3%. Plenty of UK labs still use the older, looser figures, which is why an ALT of 38 can be printed as normal and still be worth a second look.
None of that makes 38 a problem. It makes it a number worth watching, and it is a reason to look at the trend rather than one reading. The NHS puts the underlying point plainly: “Most types of liver disease do not cause any symptoms in the early stages.” Feeling fine tells you very little either way.
4. What moves your ALT from one week to the next?
More than you would guess. ALT is not a fixed personal number, and several ordinary things nudge it up for a few days.
- A hard training session, especially heavy lifting, which is why exercise before a blood test matters.
- A heavy drinking night in the days before the sample.
- Weight gain around the middle, which pushes fat into the liver.
- Some medicines and herbal supplements, green tea extract among them.
- A recent virus, including an ordinary one.
This is why a single raised ALT is usually repeated rather than acted on. If yours has come back above the line, high ALT levels covers what tends to lie behind it, and how to lower your ALT goes through what the evidence supports. A persistently raised ALT with extra weight often points at fatty liver, which is a GP conversation rather than a website one.
5. Which blood test includes ALT?
Any standard liver panel. An NHS liver function test reports ALT, and it usually arrives beside a full blood count on the same form.
Helvy's Thyroid & Vital Organs test measures ALT alongside ALP, albumin, total protein, urea, creatinine, eGFR, your thyroid hormones and your cholesterol breakdown. That is the pattern a lone ALT is missing. It is a home finger-prick kit, processed by UKAS-accredited UK labs.
Leave hard training and alcohol out of the two days before you sample, and your ALT will read closer to your real baseline. Not sure which panel fits? The build-my-test tool walks you through it in about a minute, and the metabolic health hub holds every liver guide we have written.
READY TO TEST?
See your ALT next to the markers that give it meaning
Helvy's home blood tests report ALT with the rest of your liver and kidney panel, and say what each line means. Samples are processed by UKAS-accredited UK labs.
Frequently asked questions
What is a normal ALT level in the UK?
There is no single national figure. Liverpool University Hospitals, for example, reports 41 U/L or below for men and 33 U/L or below for women. Other UK labs stop lower or go higher, so read your result against the range on your own report.
Is an ALT of 38 high?
It sits inside most male ranges and above some female ones. It would not be flagged in many UK labs. Research into healthier reference populations suggests a tighter ceiling, so 38 is a number worth repeating rather than one worth ignoring.
Why do men and women have different ALT ranges?
Lab ranges come from measuring healthy volunteers and keeping the middle 95% of results. Healthy men run higher than healthy women, so the male ceiling is set higher. Many UK labs publish the two figures separately.
Does a normal ALT mean my liver is fine?
Not on its own. ALT is one line, and the NHS says most types of liver disease cause no symptoms early on. A qualified clinician reads ALT beside ALP, albumin and your other markers rather than treating it as a pass or fail.
Does ALT change with age?
The adult range barely moves. What changes across the decades is how likely you are to sit near the top of it, mostly through weight, alcohol and medication. Your lab holds you to the same ceiling at 30 and at 70.
Can exercise raise my ALT?
Yes, for a few days. Heavy lifting and long endurance sessions both nudge it up, because muscle holds a little ALT too. Leave hard training out of the two days before a sample if you want a clean baseline.
Do I need to fast before an ALT test?
No. ALT does not need fasting. If your panel also includes cholesterol or triglycerides, a 9 to 12 hour overnight fast makes those figures more accurate, and your ALT is unaffected either way.
Related guides
ALT Blood Test UK
What the test is, when it is used and what it cannot tell you.
High ALT Levels UK
Several NHS trust ranges side by side, and what pushes ALT up.
Metabolic health hub
Every liver, kidney and blood sugar guide in one place.
Blood Test Results Explained
How to read a whole report rather than one flagged line.
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