The medical laboratory issues about recommendation on uniform cutoff values of “normal” ALT in the ACG guidelines

In the recent American clinical guidelines dealing with laboratory tests for evaluation of liver disease, the American College of Gastroenterology ( ACG) recommends ALT upper reference limits of 33 U/L for males and 25 U/L for females respectively, and that individuals with ALT above these“normal”cutoffs should be further investigated. Considering the differences between laboratory assays measuring ALT in our country, the standardization of methods and the consistency of results can not be completely ensured. The uniform “normal”range of ALT recommended by the ACG guidelines is largely based on findings from foreign studies and may not be suitable to Chinese population. On the other hand, reference upper/lower limits should not simply be equated with clinical decision thresholds. However, due to improper application of the related concepts of the above medical laboratory issues, simply recommending the uniform reference range of the ALT may lead to overdiagnosis and unnecessary follow-up examinations.