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Liver

AST (aspartate aminotransferase): normal value and what a rise means

AST, in full aspartate aminotransferase, is an enzyme: a protein that helps cells convert one substance into another. The enzyme sits mainly in the liver and in heart and skeletal muscle, and as long as those cells are intact, the amount in the blood is low.

When liver or muscle cells are damaged, AST is released into the blood and the value rises; a low value falls within the adult range at the laboratories. How much AST is in the blood can only be established with a blood test.

The AST result is given in units per litre (U/l). Star-SHL, Unilabs, Certe and Diagnostiek voor U publish an upper limit for adults of 35 U/l for men and 31 U/l for women.

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

The AST test measures how much of the enzyme aspartate aminotransferase is in the blood, in units per litre (U/l). Unilabs also calls the same enzyme GOT.

According to the NVKC, the Dutch society for clinical chemistry, AST is usually requested together with other liver tests, such as alkaline phosphatase, ALT and bilirubin. The ratio between AST and ALT gives information about how serious an abnormality is, according to the NVKC. AST sits mainly in the mitochondria, the small power plants inside the cell, which only break down with more serious cell damage, according to the NVKC.

AST (Aspartate Aminotransferase): why this value matters

A raised AST points to damaged cells, but not always to the liver: according to a 2017 review, AST is not very specific, because it is also abundant in muscles and red blood cells. Besides liver disease, a rise can also come from muscle diseases, muscle breakdown from strenuous exercise and the bursting of red blood cells, according to that review.

Star-SHL writes that the AST concentration in a red blood cell is about 10 times higher than in serum, and that haemolysis, the bursting of red blood cells, leads to falsely raised results. A 2018 British guideline calls ALT the more liver-specific value, while AST can be a more sensitive sign in alcohol-related liver disease.

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
Liver checkup · €89,-
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?

AST is requested, according to the NVKC, when a doctor suspects liver damage. The NVKC names dark urine, nausea, vomiting, a swollen belly, sudden weight gain and abdominal pain as symptoms that can point to liver damage.

According to Thuisarts, the Dutch GP information site, the GP sometimes also checks the liver tests without symptoms, for example with medicines that can damage the liver.

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

Low Levels

In adults, a low AST is not an abnormality at Star-SHL, Unilabs, Certe and Diagnostiek voor U, because the adult lower limit is 0 U/l or absent. According to the NVKC, the AST value can be lowered during pregnancy.

High Levels

An AST above 35 U/l in adult men or 31 U/l in adult women can point to damaged liver or muscle cells, or to haemolysis, the bursting of red blood cells, which according to Star-SHL gives a falsely raised result. In acute muscle breakdown, AST is at first more than 3 times as high as ALT according to a 2017 review, and after a few days that ratio approaches 1, because AST falls faster.

According to Thuisarts, an appointment with the GP is needed with yellow skin or yellow whites of the eyes, light grey stools, dark urine like strong tea, pain at the upper right of the belly, a belly that keeps growing, unexplained weight loss or getting ever 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 slightly raised AST and no clear cause, the GP can wait a few weeks and then test the blood again according to Thuisarts, if the person is not really ill. With alcohol use, Thuisarts advises stopping for a while, so the GP can see after a few weeks whether the liver tests have improved.

With excess weight, Thuisarts advises losing weight through healthy eating and more exercise, because that reduces the fat in the liver. According to Thuisarts, it is sensible to also discuss medicines, herbs and vitamins bought in a shop with the GP.

AST (Aspartate Aminotransferase): frequently asked questions

Can exercise raise the AST level?

Yes, strenuous muscle exercise can raise AST. In a Swedish study, 15 healthy men who were moderately active but not used to weightlifting did an hour of weightlifting; their AST and ALT then stayed raised for at least 7 days, while bilirubin, gamma-GT and alkaline phosphatase stayed within the normal range.

What does an AST higher than ALT mean?

An AST higher than ALT fits more serious liver damage according to the NVKC, and also damage to heart or skeletal muscle. A 2017 review calls an AST of 2 times ALT or more a sign that should make a doctor strongly suspect liver damage from alcohol.

Can AST be normal in serious liver disease?

Yes, according to a 2018 British guideline, AST and ALT can both be normal, even in liver cirrhosis, dying liver tissue. According to that guideline, the ratio between AST and ALT stays useful in adults for estimating the risk of liver fibrosis, even when both values fall within the normal range.

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

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AST (Aspartate Aminotransferase)

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