https://www.selleckchem.com/products/ll37-human.html 054). There was a significant correlation between the calculated and measured HbA (r=0.595, p<0.001). However, there was no agreement between the calculated and measured HbA . The bias ±SD (limits of agreement) for calculated versus measured HbA was -1.008±2.02% (-5.05, 2.032). Despite the presence of a significant correlation between the calculated and measured HbA , the calculated level has shown an unacceptable agreement with the measured HbA . Despite the presence of a significant correlation between the calculated and measured HbA1c , the calculated level has shown an unacceptable agreement with the measured HbA1c . The abnormal increase in serum IgG4 level is an important clinical symptom of IgG4-related disease (IgG4-RD), and the detection of serum IgG4 level is a powerful tool for the diagnosis of IgG4-RD. This study was conducted to establish a simple and rapid immunoassay for the determination of human serum IgG4 levels. Based on the competition method, a novel immunoassay was established for the determination of human serum IgG4 using a combination of time-resolved fluoroimmunoassay (TRFIA) and magnetic microspheres. IgG4 was coupled with magnetic microspheres and competed with IgG4 in the samples to bind the Eu -labeled anti-IgG4 antibody. The immunocomplex was separated and washed in a magnetic field, and the fluorescence counts were measured according to the number of dissociated europium ions. The analytical sensitivity of IgG4-TRFIA based on magnetic microspheres was 0.006g/L, and the detection range was 0.006-20g/L under optimal conditions. The precision, recovery, and specificity of this immunoassay were demonstrated to be acceptable. The clinical application of IgG4-TRFIA based on magnetic microspheres was evaluated and compared with that of immunonephelometry. The results showed that the two detection methods had a good correlation, with a correlation coefficient of .9871. IgG4-TRFIA based on m