2025 Volume 74 Issue 1 Pages 169-172
Cases of falsely low IgG levels due to the prozone phenomenon have been reported due to the discrepancy between globulin levels and the total of immunoglobulins. In IgG assay reagents, there are polyclonal antibodies that react with the subclasses from anti-IgG1 to anti-IgG4, the prozone concentrations are different for each subclass. In this case, although the immunoglobulins measured within the quantitative range of the reagent, the increase in IgG1 caused the prozone phenomenon, resulting in a false low value. To detect such cases, a method using the measured values of TP, Alb and immunoglobulins was studied. As a measure of response, a histogram of globulin and total Ig values was created to determine large differences, which was identified as +3 SD of 2.1 g/dL. Furthermore, to detect the prozone more efficiently, a reference upper limit value of 8.1 g/dL for the TP has been used. Based on the above results, a check function can be set up in the laboratory information system (LIS) for samples with a difference of more than 2.1 g/dL between globulin and total Ig and TP of more than 8.1 g/dL. To avoid missing subclass prozone phenomena, the LIS could be used.
