["Liver enzymes"--interpretation of laboratory values]

Area of Science:

• Clinical Biochemistry
• Hepatology
• Diagnostic Medicine

Background:

• Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) serum activity measurements have been standard for liver disease identification for over 50 years.
• Mild elevations in aminotransferases can be associated with systemic conditions like metabolic syndrome, not solely specific liver diseases.
• Elevated liver enzymes correlate with increased liver-associated and overall mortality.

Purpose of the Study:

• To evaluate the reliability of current upper normal limits for ALT and AST in detecting significant liver disease.
• To assess the diagnostic value of aminotransferase measurements in the context of varying demographic factors and potential underlying conditions.

Main Methods:

• Review of existing studies on aminotransferase levels, liver disease, and mortality.
• Analysis of factors influencing aminotransferase values, including gender, age, and ethnicity.
• Comparison of current diagnostic practices with findings on the reliability of upper normal limits.

Main Results:

• Aminotransferase levels exhibit variability across different genders, ages, and ethnicities in the general population.
• Current broadly applied upper limits of normal for ALT and AST are often unreliable for sensitive detection or exclusion of significant liver disease.
• Mild aminotransferase elevations can be indicative of widespread diseases beyond primary liver conditions.

Conclusions:

• The established upper normal limits for ALT and AST may not be sufficiently sensitive or specific for diagnosing liver disease across diverse populations.
• Despite limitations, aminotransferase measurement remains a critical component in the clinical decision-making process for patient diagnosis and treatment.
• Further research may be needed to refine reference ranges or develop more accurate diagnostic markers for liver health.