Comparison of four indirect methods for establishing sex- and age-specific reference intervals for IgG: based on real...

To compare four indirect methods for establishing sex- and age-specific reference intervals (RI) for adult serum immunoglobulin G (IgG) based on real world data.

All serum IgG measurement results from 2020 to 2021 in Beijing Hospital were collated. Following data screening, four indirect methods were applied to calculate the RI of the total population, different sexes, ages and seasons (months). The results were then compared with the manufacturer's RI and National Industry Standard in China to verify the reliability of the RI obtained in this study. The minimal allowable bias of the CV of the RI and the permissible difference (pD) elaborated by the German Society for Clinical Chemistry and Laboratory Medicine (DGKL) were used as the criterion.

A total of 13,162 data points were obtained. There were significant differences between men and women within the RI calculated by four methods. With increasing age, the upper limit of RI (URL) increased and the lower limit reference (LRL )decreased. However, there was no obvious trend in different seasons. The LRL of the four methods were within the pD based on manufacturer's RI, while the URL of the Hoffmann and RefineR methods conformed to the pD based on the National Industry Standard's RI, and neither the RI of the National Industry Standard nor the manufacturer's were within the minimal allowable bias of the CV of the RI with our study.

The serum IgG RI were established by four indirect method. The significant differences were found between males and females, younger and older. Clinical laboratories should establish their own RI in order to better diagnose and treat disease.