Alanine Aminotransferase (ALT), Serum — Mass Concentration
An ALT blood test measures an enzyme that is concentrated in the liver and can help assess liver injury.
["An elevated ALT result may indicate liver cell injury, but it must be interpreted alongside other liver tests and your health history."]
Key facts at a glance
- LOINC
- 26951-4
- Short code
- A alternata IgG Ser-mCnc
- Synonyms
- A alternata IgG Ser-mCnc
- Category
- liver
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 7
- Ref high
- 56
- Critical range
- — – 500 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 84484
- SNOMED
- 302773008
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
What is this test?
Alanine aminotransferase, commonly called ALT, is an enzyme found in liver cells and, in smaller amounts, in other tissues. This test measures the amount of ALT in serum, the liquid portion of a blood sample.
Why might I need this test?
Your clinician may order an ALT test to evaluate liver health, investigate symptoms such as jaundice or abdominal discomfort, or monitor certain medicines. It is often included with a liver function test panel.
How is the test performed?
A blood sample is drawn from a vein, allowed to clot, and separated to obtain serum. The laboratory then measures the ALT concentration using an approved testing method.
How do I prepare for the test?
Fasting is usually not required for an isolated ALT test, but follow any instructions from your clinician. Tell your care team about medicines and supplements you take because some can affect liver results.
Reference range
Adult males: 7-56 U/L; Adult females: 7-43 U/LN/A
No special preparation required. Avoid fatty meals before the test if possible.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
An elevated ALT result may occur with liver cell injury caused by conditions such as viral hepatitis, fatty liver disease, alcohol-related injury, or certain medicines and supplements. A low ALT result is less commonly clinically significant. ALT should be interpreted with other liver tests, symptoms, medications, and your medical history.
Short name
ALT
Frequently asked questions
Does an abnormal ALT result mean I have liver disease?
Do I need to fast before an ALT test?
Can exercise or alcohol affect the result?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 17, 2026. · Read our editorial policy