Reference intervals for serum immunoglobulins G, M and E 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.