Reference Intervals for Serum Immunoglobulin A Levels in Brazilian Children Aged 1 to 10 Years: a Population-Based Study.

Objective: To determine the reference intervals (RI) for serum levels of IgG, IgM, and IgE in healthy children aged 1-10 years living in central Brazil. Method: A sample of 1743 healthy children was randomly selected from kindergartens and public schools. Reference intervals were defined by non-parametric rank (Clinical Laboratory Standards Institute, USA), bootstrapping, and Horn's robust methods. Results: By the rank method, the IgG RI was 792-1771 mg/dL for children of both sexes aged 1-10 years. IgM RI were different for gender and age groups, being 45-196 mg/dL and 34-190 mg/dL for boys aged 1-2 years and 3-10 years, respectively. For girls, the IgM RI were 50-212 mg/dL and 39-212 mg/dL, for ages 1-4 and 5-10 years, respectively. The IgE RI for both sexes and ages 1-10 years was 6-1005 mg/dL. The bootstrap method showed RI similar to the rank method but with slightly different confidence intervals. Horn's robust method determined RI different from those obtained by previous methods. Conclusion: RI for serum concentrations of IgG, IgM, and IgE were established for Brazilian children aged 1-10 years. This definition will be useful for Brazilian physicians, who will have more adequate parameters for their clinical decision-making. (c) 2023 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).