ALT

Understanding the marker

ALT is an enzyme found mainly in liver cells. More can enter the blood when those cells are affected, so it is measured as part of a liver assessment.

ALT gives information about liver-cell injury but is not a complete measure of how the liver works. The pattern across other liver tests, symptoms, medicines and health history matters. A value within the interval does not exclude all liver disease.

What does high ALT mean?

A high ALT needs to be assessed with the other liver tests, symptoms and any medicines. The level and changes over time help guide investigation. A marked elevation can need prompt assessment; the result alone does not identify the cause.

What does low ALT mean?

An isolated low ALT is usually of limited significance. It does not replace assessment of the other liver tests or any symptoms.