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Liver

AST in women: the adult upper limit of 31 U/l and what an abnormal value means

AST is an enzyme, a protein that helps cells convert one substance into another, and it sits mainly in the liver and in heart and skeletal muscle. As long as those cells are healthy, little AST enters the blood.

Damage to liver or muscle cells makes AST in the blood rise, while a low value in adults falls within the laboratories' range. How high the AST is can only be measured with a blood test.

For adult women, Star-SHL, Unilabs, Certe and Diagnostiek voor U publish an upper limit of 31 U/l (units per litre), and for adult men 35 U/l. Unilabs applies that limit from age 19 and Certe for those older than 18.

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 49 u/l
Reference ranges by group, in u/l
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 49 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 · Female 0–31 U/l
0 31
Unilabs · Female · 19 years and older 0–31 U/l
0 31
Certe · Female · 18 years and older · a limit, not a range < 31 U/L
31
Diagnostiek voor U · Female · a limit, not a range < 31 U/L
31
0 34.1 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 the amount of aspartate aminotransferase in the blood, in U/l, and the laboratories give separate limits for women and men. Unilabs also calls the enzyme GOT, glutamate oxaloacetate transaminase.

According to the NVKC, AST is usually requested together with alkaline phosphatase, ALT and bilirubin, tests that together give insight into the state of the liver.

AST (Aspartate Aminotransferase): why this value matters

Not every raised AST has its origin in the liver. A 2017 review names, among the causes of a raised AST or ALT outside the liver, an overactive or underactive thyroid, coeliac disease (gluten hypersensitivity), Addison's disease, inflammatory bowel disease, heart failure and muscle diseases.

According to that review, coeliac disease may be found in about 5 to 10 percent of people with an unexplained raised AST or ALT, even without bowel symptoms, a figure that rests on one study.

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
Complete Metabolic Panel · €149,-
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?

A doctor requests AST on suspicion of liver damage according to the NVKC, for example with dark urine, nausea, vomiting, a swollen belly, sudden weight gain or abdominal pain. According to Thuisarts, the GP can also check the blood without symptoms, for example when someone uses medicines that can damage the liver.

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

Low Levels

A low AST is not an abnormality in adult women: Star-SHL, Unilabs, Certe and Diagnostiek voor U set the adult lower limit at 0 U/l or give none.

High Levels

An AST above 31 U/l in an adult woman lies above the limit of all four laboratories and can point to damaged liver or muscle cells. Star-SHL names haemolysis (red blood cells bursting) as a cause of a falsely raised result: according to Star-SHL, a red blood cell has an AST concentration roughly 10 times that of serum.

According to the NVKC, AST exceeds ALT in more serious liver damage, and also in damage to heart or skeletal muscle tissue.

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, Thuisarts advises discussing medicines, herbs and vitamins bought in a shop with the GP, because medicines can be the cause. Anyone who drinks alcohol can stop for a while according to Thuisarts, after which the GP can check after a few weeks whether the liver tests have improved.

AST (Aspartate Aminotransferase): frequently asked questions

Does AST change during pregnancy?

During pregnancy, AST can come out lower according to the NVKC: the NVKC names pregnancy as a situation with a possibly lowered AST value.

Can the thyroid affect AST?

An overactive and an underactive thyroid are both among the causes of a raised AST or ALT outside the liver in a 2017 review.

What happens with a slightly raised AST and no clear cause?

With a slightly raised AST and no clear cause, when the person is not really ill, the GP can wait a few weeks and then test the blood once more according to Thuisarts. According to Thuisarts, the GP can also order extra blood tests, for example for hepatitis A, B or C, or an ultrasound of the belly.

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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