What does ALT (SGPT) mean on a report?
Last content review 2026-09-23
The short answer
ALT — also printed as SGPT — is an enzyme found mainly inside liver cells. When liver cells are injured, ALT leaks into the blood, so a raised ALT suggests ongoing hepatocellular injury. It indicates that something is irritating the liver; it does not by itself say what, or how severe.
What is happening?
ALT is relatively liver-specific compared with AST.
Common contributors to a mildly raised ALT include metabolic liver disease, alcohol, certain medicines and supplements, and viral hepatitis.
ALT can fluctuate between tests, so a single value is interpreted alongside history and other results.
Why does this matter?
A persistently raised ALT should be evaluated rather than repeated indefinitely without a plan.
A normal ALT does not exclude fatty liver or fibrosis.
What does the evidence say?
The biochemical basis and clinical interpretation of aminotransferases are standard, described in the MSD Manual and society guidance on abnormal liver chemistries.
Key takeaway
ALT is an injury signal, not a diagnosis — it tells your doctor to look further, not what to conclude.
Sources & references
American College of Gastroenterology
ACG Clinical Guideline: Evaluation of Abnormal Liver Chemistries (2017) · Clinical guideline
View original sourceUS National Library of Medicine (MedlinePlus)
ALT Blood Test · Official health information
View original source
This page is general health education. It is not a diagnosis, and it cannot replace advice from your treating doctor. Never start or stop a prescribed medicine based on what you read here.