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Liver

AST with a fatty liver: what the ratio with ALT shows

AST is an enzyme in your liver and in your heart and skeletal muscles: a protein that helps cells convert one substance into another. In healthy cells it stays inside, so normally there is little of it in your blood.

When liver or muscle cells are damaged, your AST can rise, for example with a fatty liver, in which there is too much fat in your liver. Only a blood test can measure how much AST is in your blood.

Your AST result is given in units per litre (U/l); the upper limit at Star-SHL, Unilabs, Certe and Diagnostiek voor U is 35 U/l for adult men and 31 U/l for adult women. Thuisarts lists a fatty liver among the possible reasons for abnormal liver tests.

Doctor's Assessment Included

AST is an enzyme from liver and muscle cells that enters the blood when those cells are damaged. Star-SHL, Unilabs, Certe and Diagnostiek voor U use the same upper limit for adults: 35 U/l for men and 31 U/l for women.

  • With mild liver damage ALT is higher than AST according to the NVKC; with more serious damage to the liver cells AST is higher.
  • Haemolysis, the bursting of red blood cells, gives a falsely raised result according to Star-SHL, because the AST concentration in a red blood cell is about 10 times higher than in serum.
  • According to the NVKC, AST is usually measured together with ALT, alkaline phosphatase and bilirubin.

Reference Ranges

See the value that applies to you:

Choose male or female — this range differs by sex.

Enter your age — this range changes with age.

This range also depends on context such as cycle phase or sample material; the highlighted rows apply to your group.

Your reference range
u/l
12 53 u/l
Reference ranges by group, in u/l
Male · 1–5 years 24–53 u/l
24 53
Male · 6–12 years 19–42 u/l
19 42
Male · 13–18 years 14–39 u/l
14 39
Male · 19 years and older 14–43 u/l
14 43
Female · 1–5 years 23–49 u/l
23 49
Female · 6–12 years 15–46 u/l
15 46
Female · 13–18 years 12–33 u/l
12 33
Female · 19 years and older 13–38 u/l
13 38
12 53 u/l

Source: NVKC Reference population: Dutch general-practice population (NUMBER, n = 7,574,327)

Reference ranges may vary between laboratories. When you order a test, a BIG-registered doctor assesses your personal results in context. For treatment decisions, discuss your results with your GP.

Check your own value

AST (Aspartate Aminotransferase): what Dutch laboratories use

Reference ranges by group, in u/l
Star-shl · Male 0–35 U/l
0 35
Star-shl · Female 0–31 U/l
0 31
Unilabs · Male · 19 years and older 0–35 U/l
0 35
Unilabs · Female · 19 years and older 0–31 U/l
0 31
Certe · Male · 18 years and older · a limit, not a range < 35 U/L
35
Certe · Female · 18 years and older · a limit, not a range < 31 U/L
31
Diagnostiek voor U · Male · a limit, not a range < 35 U/L
35
Diagnostiek voor U · Female · a limit, not a range < 31 U/L
31
0 38.5 u/l

Source: Star-shl

Source: Unilabs

Source: Certe

Source: Diagnostiek voor U

Each value as the laboratory itself publishes it, retrieved in 2026.

AST (Aspartate Aminotransferase): what this test measures

An AST result gives, in units per litre (U/l), the amount of aspartate aminotransferase your blood contains. With non-alcoholic fatty liver disease (NAFLD), mildly raised liver enzymes are sometimes the only abnormal blood test according to a 2017 review.

AST (Aspartate Aminotransferase): why this value matters

The ratio between AST and ALT says something about the state of the liver in non-alcoholic fatty liver disease (NAFLD). According to a 2017 review, a reversed ratio in NAFLD, with AST higher than ALT, is a sign of a poorer outlook that can point to early or advanced fibrosis: scars where liver cells were destroyed.

In adults with abnormal liver blood tests, an AST/ALT ratio above 1 indicates advanced fibrosis or cirrhosis, dying liver tissue, according to a 2018 British guideline.

AST (Aspartate Aminotransferase): how the blood test works

Referral
No GP referral needed. After the order we arrange the referral through ZorgDomein, within one business day; orders after 17:00 or at the weekend start on the next business day. ZorgDomein emails a barcode, and that barcode is what the draw site needs.
The draw
A blood draw from a vein in the arm, at a partner laboratory's draw site. No home kit, no finger prick.
Which test
GLP-1 Check-in Panel · €109,- · GLP-1 Extended Panel · €196,- · GLP-1 Baseline Panel · €214,-
Where
650+ draw sites run by independent laboratories across the Netherlands. Draw sites

AST (Aspartate Aminotransferase): how to prepare

  1. No hard training beforehand

    Required

    No heavy training, long endurance sessions or anything that leaves you out of breath in the 48 hours before the draw. Normal walking is fine.

  • Water is always fine. Drink as usual beforehand, it makes the draw easier.
  • Take your usual medication, unless your own doctor told you otherwise.

AST (Aspartate Aminotransferase): when is testing worthwhile?

According to Thuisarts, your GP has liver tests, AST among them, done among other things when your liver feels too large on examination, and sometimes without symptoms, for example with medicines that can damage the liver. According to a 2018 British guideline, the AST/ALT ratio stays useful in adults for estimating the risk of liver fibrosis, even when both values fall within the normal range.

AST (Aspartate Aminotransferase): symptoms of a high or low value

Low Levels

At Star-SHL, Unilabs, Certe and Diagnostiek voor U the adult lower limit for AST is 0 U/l or absent, so a low value is not an abnormality there. According to a 2018 British guideline, a normal AST does not rule out advanced liver disease: AST and ALT can both be normal, even in liver cirrhosis, dying liver tissue.

High Levels

A raised AST can fit a fatty liver, but for abnormal liver tests Thuisarts also names medicines, alcohol, a viral liver inflammation, gallstones and drugs as possible causes. Thuisarts advises an appointment with your GP when your skin or the whites of your eyes turn yellow, your belly keeps growing, you lose weight without knowing why or you keep getting more ill.

AST (Aspartate Aminotransferase): causes of a low or high value

What lowers the value

  • Pregnancy

    ASAT can be lower during pregnancy.

What raises the value

  • Liver inflammation (hepatitis)

    In liver inflammation, whether caused by a virus or not, ASAT can stay raised for months.

  • Heavy drinking

    Alcohol can damage the liver, after which ASAT leaks from liver cells into the blood.

  • Medicines

    Some medicines can damage the liver and so raise ASAT.

  • Muscle damage

    ASAT is also found in heart and skeletal muscle; in muscle damage ASAT is higher than ALAT.

  • Burst red blood cells in the tube

    A red blood cell holds about 10 times as much ASAT as serum, so blood damaged in the tube gives a falsely high result.

AST (Aspartate Aminotransferase): lifestyle and this value

With a raised AST and excess weight, Thuisarts advises losing weight by eating healthily and moving more, because that reduces the fat in your liver. An ultrasound of your belly can show why the liver tests are off according to Thuisarts, for example because of a fatty liver, but an ultrasound does not always find a cause.

AST (Aspartate Aminotransferase): frequently asked questions

Is ALT or AST higher with a fatty liver not caused by alcohol?

With non-alcoholic fatty liver disease (NAFLD), ALT is usually higher than AST according to a 2017 review, so the AST/ALT ratio lies below 1.

Can gamma-GT be raised in fatty liver disease not caused by alcohol?

Next to AST, gamma-GT can be raised in about half of the people with non-alcoholic fatty liver disease (NAFLD) according to a 2017 review, up to 3 times the upper limit, even without alcohol use.

AST (Aspartate Aminotransferase): sources

  1. den Elzen WPJ, Brouwer N, Thelen MH, Le Cessie S, Haagen I-A, Cobbaert CM. NUMBER: standardized reference intervals in the Netherlands using a 'big data' approach. Clin Chem Lab Med 2018;57(1):42-56. (retrieved 2026) doi.org
  2. Star-shl, Labbepalingen (referentiewaarden per bepaling), star-shl.nl, geraadpleegd 2026-10-01 (retrieved 2026) star-shl.nl
  3. Unilabs, Bepalingenklapper (referentiewaarden per bepaling), bepalingenklapper.nl, geraadpleegd 2026-10-01 (retrieved 2026) bepalingenklapper.nl
  4. Certe, Bepalingenwijzer (referentiewaarden per bepaling), bepalingenwijzer.certe.nl, geraadpleegd 2026-10-01 (retrieved 2026) bepalingenwijzer.certe.nl
  5. Diagnostiek voor U, eLabgids (Referentiewaarden DvU), diagnostiek.getincontrol.eu, geraadpleegd 2026-10-01 (retrieved 2026) diagnostiek.getincontrol.eu
  6. NVKC, Alles over testen: ASAT, allesovertesten.nl, geraadpleegd 2026-10-03 (retrieved 2026) allesovertesten.nl

Test Products

This marker is included in the following test panels.

GLP-1

GLP-1 Check-in Panel

The 3-month safety and progress check clinics do: pancreas, liver, kidneys, salts and your metabolic progress on GLP-1 medication.

ALT (Alanine Aminotransferase) AST (Aspartate Aminotransferase) HDL Cholesterol HbA1c (Glycated Hemoglobin) Potassium Sodium Glucose (Fasting) Total Cholesterol Lipase Creatinine Triglycerides eGFR (Estimated Glomerular Filtration Rate) LDL Cholesterol Cholesterol/HDL Ratio Non-HDL Cholesterol LDL/HDL Ratio
€109,-
GLP-1

GLP-1 Extended Panel

The 6-month measurement: everything from the check-in plus insulin, ApoB and your nutrients — especially relevant if you have been eating much less for a while.

Insulin (Fasting) ALT (Alanine Aminotransferase) AST (Aspartate Aminotransferase) HDL Cholesterol HbA1c (Glycated Hemoglobin) ApoB (Apolipoprotein B) Vitamin B12 Ferritin Potassium Sodium Glucose (Fasting) Total Cholesterol Albumin Lipase Creatinine Vitamin D (25-OH) Triglycerides HOMA-IR eGFR (Estimated Glomerular Filtration Rate) LDL Cholesterol Cholesterol/HDL Ratio Non-HDL Cholesterol LDL/HDL Ratio
€196,-
GLP-1

GLP-1 Baseline Panel

Your starting point before the first injection: blood sugar, cholesterol, pancreas, liver, kidneys, thyroid and nutrients in one measurement.

Insulin (Fasting) ALT (Alanine Aminotransferase) TSH (Thyroid Stimulating Hormone) AST (Aspartate Aminotransferase) HDL Cholesterol HbA1c (Glycated Hemoglobin) Bilirubin (Total) ApoB (Apolipoprotein B) Vitamin B12 Ferritin Potassium Sodium Glucose (Fasting) Total Cholesterol Albumin Lipase Creatinine Vitamin D (25-OH) Triglycerides Bilirubin (Direct) Bilirubin (Indirect) HOMA-IR eGFR (Estimated Glomerular Filtration Rate) LDL Cholesterol Cholesterol/HDL Ratio Non-HDL Cholesterol LDL/HDL Ratio
€214,-

Medical reviewer

Medical standards

Dr. Naimi oversees the medical standards behind our content and assessments.

Medical policy
CIBG Ministerie van Volksgezondheid,
Welzijn en Sport Official BIG registration BIG 49928676701 Opens in a new tab

AST (Aspartate Aminotransferase)

€9,-