Blood WorkALT (alanine aminotransferase) is a liver enzyme that leaks into the blood when liver cells are irritated or damaged. It's part of a comprehensive metabolic panel (CMP). Lab ranges often go up to about 36 to 56 U/L, but the American College of Gastroenterology puts a healthy ALT at about 29 to 33 U/L for men and 19 to 25 U/L for women. The most common cause of a mildly high ALT is fatty liver; others include alcohol, medicines, supplements and hepatitis.
What does ALT measure?
ALT is an enzyme found mostly in liver cells. A small amount in your blood is normal; more than usual means liver cells are being irritated or injured. Clinicians read it with AST, alkaline phosphatase, bilirubin and albumin, which together are often called liver function tests.
What is a normal ALT?
| Result | What it usually means |
|---|---|
| Up to about 29 to 33 U/L (men), 19 to 25 U/L (women) | Healthy range in the ACG guideline. Many lab reports print a higher upper limit. |
| Up to 5 times the upper limit | Borderline to mild: most often fatty liver, alcohol or medicines. |
| 5 to 15 times the upper limit | Moderate: needs a prompt workup, within days. |
| Above about 15 times the upper limit (often over 1,000 U/L) | Severe: acute hepatitis, medicine or acetaminophen injury, or poor blood flow to the liver. Needs same-day care. |
Your lab's printed range applies. Heavy or new workouts, especially weightlifting, can raise ALT and AST for up to a week.
What causes high ALT?
- Fatty liver (MASLD), the most common cause, especially with extra weight, diabetes or high triglycerides. See fatty liver care.
- Alcohol, often with AST higher than ALT.
- Medicines and supplements: acetaminophen, some antibiotics, statins (usually mild), and herbal or bodybuilding supplements.
- Viral hepatitis B or C. See hepatitis B and C testing.
- Less common: celiac disease, thyroid disease, iron overload (hemochromatosis), autoimmune hepatitis and muscle injury.
Go to the ER if a high ALT comes with confusion, unusual sleepiness or easy bleeding. Get care the same day for yellow skin or eyes, dark urine or severe belly pain. If you may have taken too much acetaminophen (Tylenol), call Poison Control at 1-800-222-1222 or go to the ER now, even if you feel fine.
What happens after a high ALT?
For a mild rise without symptoms, the ACG guideline suggests repeating the test and looking for the cause: alcohol, medicines and supplements, weight, hepatitis B and C, and other blood tests. Your AST, ALT, platelet count and age give a FIB-4 score for liver scarring. If you have fatty liver or its risk factors, a score of 1.3 or higher usually leads to a liver stiffness scan (some guidelines use 2.0 after age 65).
If your ALT is high at Passion Health
A Texas-licensed clinician reviews every result and calls you the same day about anything critical. One result outside the range is common and often harmless; we read it with the rest of your panel, your history and your medicines, and recheck when that's the sensible next step.
We review alcohol, medicines and supplements, check hepatitis B and C, calculate FIB-4 from Essential Blood Work, and arrange a FibroScan liver health assessment at a Passion Health clinic when it's indicated.
ALT test cost in Texas
Self-pay. ALT comes with every comprehensive metabolic panel. In Essential Blood Work ($59) it's part of 33 results with the draw and a clinician's review included; on its own, the metabolic panel is $20 plus the $29 draw and review fee ($49).
With insurance. If we're in network with your plan, we bill it when the test is covered. You pay cash for a test only after we tell you the price in writing, and Medicare patients sign an Advance Beneficiary Notice first.
ALT blood test questions
What is ALT in a blood test?
ALT, alanine aminotransferase, is a liver enzyme. Higher than normal levels mean liver cells are irritated or damaged. It's part of a comprehensive metabolic panel.
What is a normal ALT level?
The American College of Gastroenterology puts a healthy ALT at about 29 to 33 U/L for men and 19 to 25 U/L for women. Many labs print a higher upper limit, often 36 to 56 U/L.
What is the most common cause of high ALT?
Fatty liver, linked to extra weight, diabetes and high triglycerides. Alcohol, medicines, supplements and viral hepatitis are other common causes.
Can exercise raise ALT?
Yes. Heavy or new workouts, especially weightlifting, can raise ALT and, even more, AST for up to a week. Avoid unusually hard workouts for a few days before a liver test.
How can I lower my ALT?
Treat the cause. For fatty liver, losing 5% to 10% of body weight, cutting alcohol and sugary drinks, and staying active usually bring ALT down. Stop supplements your clinician flags, and don't stop prescribed medicines without asking.
Sources
- ACG Clinical Guideline: Evaluation of Abnormal Liver Chemistries, American Journal of Gastroenterology, 2017
- AASLD Practice Guidance on the clinical assessment and management of nonalcoholic fatty liver disease, Hepatology, 2023
- MedlinePlus: Alanine transaminase (ALT) blood test
- MedlinePlus: Liver Function Tests