Aminotransferase levels in clinical practice - what is normal?

Area of Science:

• Clinical Biochemistry
• Hepatology
• Laboratory Medicine

Background:

• The upper limit of normal (ULN) for alanine aminotransferase (ALT) lacks universal consensus, leading to diagnostic variability.
• Significant differences exist in ALT reference values between laboratories, ranging from 30 to 60 U/L.

Purpose of the Study:

• To review the wide variation in ALT ULN.
• To identify key factors contributing to these differences.
• To propose solutions for standardizing ALT reference ranges.

Main Methods:

• Review of existing literature on ALT reference ranges.
• Analysis of factors influencing ALT assay variability.
• Evaluation of studies proposing new ALT cut-offs.

Main Results:

• Laboratory-specific ALT ULN values show considerable two-fold variation.
• Differences in reference populations, analyzers, and assays are primary causes for variability.
• Studies suggest revised ALT cut-offs for improved liver disease detection.

Conclusions:

• Standardizing ALT reference ranges remains a critical unmet need in clinical practice.
• Harmonization of analyzer methods and rigorous inclusion criteria for reference populations are essential.
• Universal standardization of ALT reference ranges requires collaborative efforts.