🫀 Liver Function

ALT: What It Means for Your Health

ALT (alanine aminotransferase, formerly SGPT) is an enzyme predominantly found in liver cells. When liver cells are damaged or destroyed, ALT is released into the bloodstream, causing levels to rise. ALT is considered the most liver-specific of the common liver enzymes (more so than AST) and is a primary screening tool for liver disease. Mild elevations are extremely common and often related to fatty liver disease.

Full Name
Alanine Aminotransferase (ALT/SGPT)
Normal Range
0–41 U/L
Also Known As
SGPT, Alanine Aminotransferase, ALT (SGPT)

Reference Range

LowNormal: 0–41 U/LHigh

Reference ranges may vary between laboratories, age groups, and sexes. The values shown are general adult reference ranges. Always compare your results to the specific range provided by your testing laboratory.

What Is ALT?

ALT (alanine aminotransferase, formerly SGPT) is an enzyme predominantly found in liver cells. When liver cells are damaged or destroyed, ALT is released into the bloodstream, causing levels to rise. ALT is considered the most liver-specific of the common liver enzymes (more so than AST) and is a primary screening tool for liver disease. Mild elevations are extremely common and often related to fatty liver disease.

Commonly included in:

Liver Function PanelHepatic PanelComprehensive Metabolic Panel

What Does High ALT Mean?

Above 41 U/L

Elevated ALT indicates liver cell damage. Common causes include non-alcoholic fatty liver disease (NAFLD, the most common cause of mildly elevated ALT), alcohol-related liver disease, viral hepatitis (A, B, C), medications (acetaminophen, statins), autoimmune hepatitis, and celiac disease. Very high levels (>1000 U/L) suggest acute viral hepatitis, drug toxicity, or ischemic liver injury.

What Does Low ALT Mean?

Below 0 U/L

Low ALT is generally not clinically significant. Very low levels have been associated with vitamin B6 deficiency (since ALT requires B6 as a cofactor) and, in some studies, with frailty in elderly patients.

Related Biomarkers in Liver Function

AST
Enzyme found in liver, heart, and muscle — rises with tissue damage.
Range: 0–40 U/L
GGT
Liver enzyme particularly sensitive to alcohol consumption and bile duct obstruction.
Range: 0–55 U/L
ALP
Enzyme found in liver, bone, kidneys, and intestines.
Range: 44–147 U/L
Total Bilirubin
Yellow pigment from red blood cell breakdown processed by the liver.
Range: 0.1–1.2 mg/dL
Albumin
Most abundant blood protein, made by the liver, essential for fluid balance.
Range: 3.5–5.5 g/dL

Track Your ALT Over Time

Upload your blood test results to Hemoly and see how your ALT levels change over time. Get trend analysis, educational insights, and a personal health timeline.

Download Hemoly for iOS

Medical Disclaimer

This information is for educational purposes only and is not intended as medical advice, diagnosis, or treatment. Reference ranges may vary between laboratories. Always consult a qualified healthcare professional for interpretation of your blood test results and before making any health decisions.