Clinical Health Hub

Lab test guide

Understanding ALT and AST liver tests

ALT and AST are enzymes that can provide clues about liver and other tissue injury.

Written by: Clinical Health Hub Editorial Team · Last reviewed 09 September 2026

What the test is

This test measures alanine transaminase and aspartate transaminase. Results are interpreted with your history, symptoms and the laboratory's own reference information.

Why it may be ordered

A healthcare professional may order it for investigating symptoms, medicines or other results. The reason for testing varies from person to person.

What it measures

The report may include alanine transaminase and aspartate transaminase. Ask which markers were requested and what each one means.

Understanding your result

A higher result can have several possible explanations and does not diagnose a condition by itself. Your clinician will interpret the pattern and context. A lower result can also have several possible explanations. A result outside a reference range is not automatically a diagnosis.

Factors that can affect results

Reference ranges and results can vary by laboratory, method, age, sex where clinically relevant, pregnancy and individual circumstances. Medicines, supplements, hydration, recent illness and timing may also matter.

Questions to ask a healthcare professional

Ask why the test was ordered, which result matters most for you, whether you need a repeat test and what follow-up is appropriate.

When professional advice may be appropriate

Seek professional advice for personal interpretation, persistent symptoms or concerns about a result. For urgent symptoms, contact local emergency services.

References & editorial standards

This page uses the linked references below for general educational context.

References
View sources & standards

This page is not a substitute for professional medical advice, diagnosis or treatment. Contact an appropriately qualified healthcare professional with personal questions.