Variability in Upper Limit of Normal for ALT

Labs varied greatly in criteria for “healthy volunteers.”

Have you ever wondered why upper limits of normal for some tests vary considerably from lab to lab? Researchers investigated this issue for alanine aminotransferase, which is used widely to diagnose or to monitor hepatocellular disorders. They surveyed 108 clinical laboratories in Indiana: 67 responded.

The upper limit of normal for ALT ranged from 31 U/L to 72 U/L among respondents, with slight differences for men and women. Most labs used one of four chemical analyzers made by four different companies. Labs varied in how they established their ALT reference ranges: 39% used the manufacturer's recommendation only, 17% tested local healthy volunteers only, and 40% used both methods. For labs that tested healthy volunteers, the median number …

Reviewing Author

Allan S. Brett, MD

Disclosures

Nothing to disclose

Allan S. Brett, MD

Disclosures

Nothing to disclose