What is the normal reference range for Alanine Aminotransferase (ALT)?

Generally, the normal reference range for alanine aminotransferase (ALT) should be determined according to the testing method and population differences. Clinically, continuous monitoring and colorimetric methods are commonly used, with different standards for adults and children. Detailed analysis is as follows:

When using the continuous monitoring method, the normal value for adults is typically 0-40 U/L, which is the standard reference range for the currently widely used detection method. An 8- to 12-hour fast is required before testing, and strenuous exercise, alcohol consumption, and medications causing liver damage should be avoided to prevent affecting the accuracy of results.

When using the colorimetric method, the normal range is generally 5-25 U/L. The values obtained by this method tend to be relatively lower, and some institutions still use this method. It is important to refer to the reference range indicated on the test report to avoid confusion with other methods.

In children, the normal value is usually slightly lower than in adults, generally 0-30 U/L using the continuous monitoring method. Before testing, it is important to ensure children have sufficient sleep and avoid taking prohibited or caution-indicated medications. Results should be comprehensively evaluated in combination with their growth and development status.

Different testing institutions may use different instruments and reagents, so each report will indicate the specific reference range. If the values are abnormal, retesting can be performed after an interval of 1-2 weeks. Before retesting, fasting and alcohol abstinence requirements should still be followed. Maintaining a regular lifestyle, eating a light diet, avoiding staying up late, and excessive alcohol consumption can help maintain normal ALT levels.