A reference interval for serum IgG subclasses in Chinese children

BACKGROUND Reference intervals (RIs) for serum IgG subclasses vary greatly among different geographical regions. The present study aimed to establish RIs for serum IgG subclasses in Chinese children, which is essential for interpretation of laboratory findings and making clinical decisions. METHODS This study was performed in accordance with guideline C28-A3, proposed by the International Federation of Clinical Chemistry and the Clinical and Laboratory Standards Institute. In total, 607 apparently healthy Chinese children were enrolled, and serum levels of IgG subclasses were measured. Individuals were stratified by age and the RIs were determined through statistical analysis. RESULTS Following were the median values of RIs for serum IgG subclasses in Chinese children: IgG1, 2.78 g/L; IgG2, 0.85 g/L; IgG3, 0.13 g/L; IgG4, 0.06 g/L at 1-6 months of age; IgG1, 3.64 g/L; IgG2, 0.73 g/L; IgG3, 0.19 g/L; IgG4, 0.03 g/L at 6-12 months of age; IgG1, 5.15 g/L; IgG2, 0.87 g/L; IgG3, 0.19 g/L; IgG4, 0.07 g/L at 1-2 years of age; IgG1, 5.26 g/L; IgG2, 1.23 g/L; IgG3, 0.14 g/L; IgG4, 0.11 g/L at 2-3 years of age; IgG1, 6.33 g/L; IgG2, 1.8 g/L; IgG3, 0.2 g/L; IgG4, 0.21 g/L at age 3-4 years; IgG1, 7.05 g/L; IgG2, 1.87 g/L; IgG3, 0.25 g/L; IgG4, 0.29 g/L at 4-6 years of age; IgG1, 6.19 g/L; IgG2, 1.93 g/L; IgG3, 0.2 g/L; IgG4, 0.28 g/L at 6-9 years of age; IgG1, 6.76 g/L; IgG2, 2.29 g/L; IgG3, 0.27 g/L; IgG4, 0.37 g/L at 10-12 years of age; IgG1, 7.45 g/L; IgG2, 2.92 g/L; IgG3, 0.28 g/L; IgG4, 0.38 g/L at 13-16 years of age. CONCLUSION To our knowledge, this study is the first to establish RIs for serum IgG subclasses exclusively in Chinese children.