EmpeiriaAspartate aminotransferase
Also known as
AST, SGOT, serum glutamic-oxaloacetic transaminase
enzyme activity · no single molecular formula
unverified These explanations are written to be easy to read and have not yet been checked against a source. The ranges and measurement notes on this page show theirs.
definition unverified
An enzyme found in the liver, but also in heart and skeletal muscle and in red blood cells. A raised level means cells somewhere have been damaged, and the other tests say where.
An enzyme found in the liver, but also in heart and skeletal muscle and in red blood cells. A raised level means cells somewhere have been damaged, and the other tests say where.
No clinical version written yet.
if high unverified
Often the liver. But hard exercise, a pulled muscle, or a blood sample that was shaken on the way to the lab will all raise it too. None of those mean anything is wrong with your liver.
Often the liver. But hard exercise, a pulled muscle, or a blood sample that was shaken on the way to the lab will all raise it too. None of those mean anything is wrong with your liver.
No clinical version written yet.
caveats unverified
Because it comes from several tissues, it is read next to ALT rather than on its own. A rise in AST with a normal ALT often points away from the liver.
Because it comes from several tissues, it is read next to ALT rather than on its own. A rise in AST with a normal ALT often points away from the liver.
No clinical version written yet.
What this substance is
EC 2.6.1.1
L-aspartate + 2-oxoglutarate = oxaloacetate + L-glutamate
Requires pyridoxal 5'-phosphate.
UniProt P17174
Each molecule is drawn from ChEBI's curated 2D drawing, accepted only after its InChIKey, formula and charge matched the ChEBI release. Atom diagrams are checked against the NIST Atomic Spectra Database.
3D model
Predicted structure of one AST chain (AlphaFold). The working enzyme is a pair of chains. Predicted by AlphaFold (model v6, average confidence 96 of 100); its sequence matches UniProt exactly. Colour is AlphaFold's own confidence for each part: dark blue very high (above 90), light blue confident (70-90), yellow low (50-70), orange very low (below 50). Drag to rotate, scroll to zoom.
Reference ranges
Checking your own result against this range needs the running application; this is a static copy. Nothing you type anywhere in Empeiria is ever sent to a server.
This open edition shows a range only where a public-domain or openly licensed source states one, and none does for this marker yet. Compare your result with the range printed on your own lab report.
How it is measured
In practice
A health worker takes a small blood sample from a vein in your arm with a needle. It usually takes less than five minutes. AST is usually checked along with other blood tests, so you may need to skip food and drink for up to 12 hours first.
Serum, or EDTA- or heparin-anticoagulated plasma, from venipuncture; separated serum or plasma should be removed from cells within one hour. Haemolysis interferes because erythrocytes contain AST, so haemolysed specimens should not be analysed. Usually ordered with other tests, for which patients may fast for up to 12 hours.
Before the test
- Fast (no food or drink) for up to 12 hours if your provider asks, since AST is usually ordered with other blood tests.
- Tell your provider about everything you take, but do not stop any medicine unless your provider tells you to.
Where: laboratory
Sources: AST Test, MedlinePlus (U.S. National Library of Medicine); NHANES 2017-2018 Laboratory Procedure Manual, Aspartate Aminotransferase (AST) (CDC National Center for Health Statistics) cited · not yet checked by a person
In the lab
IFCC-based kinetic UV (NADH/MDH coupled)
AST is a helper protein that speeds up a chemical reaction. The machine adds the ingredients for that reaction and times how fast a light-absorbing chemical gets used up. The faster it disappears, the more AST is in the blood.
AST transfers an amino group from L-aspartate to alpha-ketoglutarate, and the oxaloacetate formed is reduced to malate by malate dehydrogenase while NADH is oxidised; the rate of absorbance fall at 340 nm is proportional to AST activity (a modification of the IFCC-recommended method).
- Read by: Rate of NADH absorbance decrease at 340 nm (secondary 700 nm)
What can throw it off
- Haemolysis (red cells contain AST)
- Isoniazid (falsely low)
- Furosemide (falsely high)
- Hydroxocobalamin (Cyanokit)
- IgM gammopathy (rare)
Sources: Koerbin G et al. Bias Assessment of General Chemistry Analytes using Commutable Samples. Clin Biochem Rev 2014;35:203-211 (PMC4310060); NHANES 2017-2018 Laboratory Procedure Manual, Aspartate Aminotransferase (AST), CDC/NCHS cited · not yet checked by a person
What it reports on
-
hepatocyte
released on injury
AST is found mainly in the liver, so damaged liver cells (hepatocytes) release it into the blood.
-
liver
released on injury
AST is found mainly in the liver, and a damaged liver releases it into the blood.
-
skeletal muscle organ, vertebrate
released on injury
AST is also found in skeletal muscle, so muscle damage can raise AST in the blood.
-
heart
released on injury
AST is also found in the heart, so heart damage can raise AST in the blood.
Associated symptoms
- high Feeling tired all the time · non specific · common
-
high
Muscles feeling weak
· non specific · occasional
Present when the source is muscle rather than liver.
Conditions this marker features in
-
high
Fatty liver
· supportive
A raised AST, with ALT, can make a doctor suspect it; AST is also one input to the FIB-4 scarring score.
-
high
Liver damage from alcohol
· supportive
Part of the consensus criteria for alcohol-related hepatitis: AST above 50 but below 400 IU/L, with an AST:ALT ratio above 1.5. Classically higher than ALT.