Normal range: 7 – 55 U/L (lower is better)
ALT is an enzyme concentrated in your liver cells. When those cells are damaged or inflamed, ALT leaks into the bloodstream, so a blood test can pick it up. It is the most specific marker of liver injury. Elevated ALT is commonly seen in fatty liver disease, viral hepatitis, alcohol use, and medication-related liver stress. Even mildly elevated ALT over time is associated with increased risk of liver disease progression.
ALT isn't sold on its own. It comes in a comprehensive metabolic panel, about $40. A fuller workup adds Vitamin D ($75), hs-CRP ($69), ApoB ($50), and ApoA1 ($50). You can test ALT and 100 other biomarkers for $190 as part of an Empirical membership.
Empirical is FSA/HSA eligible, so you can pay with pre-tax dollars. Fast for 8-12 hours beforehand for the most accurate lipid and metabolic results, and expect results in days rather than weeks.
ALT is an enzyme found mainly in the liver. High levels may indicate liver damage.
In NHANES 2021-2023, the median ALT was about 16 U/L for adults aged 18-29 and 16 U/L for adults aged 70 and older. The chart below shows the full distribution by age and sex.
Median ALT by age and sex, with the 10th to 90th percentile band. Source: NHANES 2021-2023 (weighted estimates).
A normal ALT is 7 – 55 U/L. Lower is better.
Non-alcoholic fatty liver disease (NAFLD) is now the most common cause of elevated ALT, driven by obesity and insulin resistance. Losing even 5-10% of body weight can significantly lower ALT in people with fatty liver. Alcohol use, viral hepatitis (B and C), and medications (especially acetaminophen, statins, and certain antibiotics) are other frequent causes.
Intense exercise can temporarily spike ALT for 24-48 hours. Herbal supplements (especially kava, green tea extract, and comfrey) are an underappreciated cause of liver injury and elevated ALT.
Lifestyle changes are the frontline treatment for elevated ALT. Cutting back on alcohol, losing excess weight, exercising regularly, and reducing sugar intake can all bring levels down. If you take regular medications, your doctor may monitor ALT periodically to catch liver stress early.
ALT is most highly correlated with AST and Ferritin. Here are the top biomarkers correlated with ALT, based on 500,000 tests done by Empirical Health.
The percentage shows how strongly two biomarkers move together. A higher number means the relationship is stronger. Green = rises and falls together. Orange = one rises as the other falls.
ALT is drawn at 2,200+ Quest and BioReference patient service centers across the US, so there's usually one within a short drive. Browse the full directory to find the one closest to you.
Test your ALT (Alanine Aminotransferase) and 100+ other biomarkers in a single blood draw.
