A case of ALT unmeasurable due to abnormal reaction time course

Abstract

Ordinarily, reaction time course in measurement of alanine aminotransferase (ALT) after adding a second reagent is decrease gradually in 340 nm, but we experienced a case in which an increase in absorbance was observed. Increasing an absorbance occurred at all 14 wavelengths used for the measurement. Immunoglobulin levels (IgG, IgA, and IgM) were within the standard range and no M protein was detected, but the results of immunoglobulin absorption test and reduction treatment indicated that IgM caused an abnormal reaction. To improve performance, some commercially available reagents contain ingredients other than the main ones. Considering the possibility that abnormal reactions may arose from there reagents, we measured the sample with the reagent prepared ourself, but the reaction time course was the same. When a surfactant was added to the first reagent of both the self-prepared reagent and the current reagent, the reaction time courses after adding a second reagent were not increased, and became common. These results suggest that the presence of strongly hydrophobic IgM may affected the ALT measurement.