Reference values of total IgE in estonian children

Background: The value of total IgE varies in wide limits (0 – 5000 kU/l) and depends on a lot of factors: genetics, allergy, parasitic infection, age, gender, immune status and geographic region. The aim of this study was to find out the factors influencing the values of total IgE in Estonian children and to establish own reference values.

Methods: The study group comprised 385 children from two prospective allergy studies followed from birth up to the age 16 years. Data about allergy symptoms were collected from the interview-questionnaires, clinical examinations were carried out and skin prick tests were made with the most common food and inhalant allergens during the follow-up investigations. The measurements of total IgE level in sera were made at birth, 3, 6, 12, months and 2, 5, 10/12, 16/18 years of life using UniCAP method.

Results: The cord blood IgE level did not have any predictive value for allergy development during the first 12 years of life. The value of total IgE increased with the age from 0.4 (95%CI 14.4) kU/l at 3 months of age up to 37.0 (95%CI 45.5) kU/l at the age of five years. The teenage reference value at 10/12 years was lower (34.2 (95%CI 41.2) kU/l) as compared to the preschool children and at the age of 16/18 years (30.0 (95%CI 38.7). Males had higher IgE values in comparison with females at every age, but statistically significant was the difference only at 6 months (3.28 vs. 1.76 kU/L; p=0.01) and at two years (21.8 vs. 11.9 kU/l; p=0.01) of age. The total IgE was higher in children with allergic diseases as compared to non-allergic only at the age of 10/12 years (75.8 vs. 44.3 kU/l; p=0.008), which might indicate quite high prevalence of parasites in non-allergic children. We tested IgE antibodies against Ascaris in children with total IgE level over 20 kU/ at 6 and 12 months and over 200 kU/l at 2, 5, 10/12 and 16/18 years of life. Antibodies against Ascaris were found in 29 of 50 preschool children and in 31 of 56 teenagers.

However, there was positive correlation between total IgE and atopy considering positive skin prick test results and presence of allergen specific IgE antibodies in sera in all age groups.

Conclusion The peak value of total IgE was at the age of five and not in teenage as usually referred to in the laboratory manuals. There was positive correlation between total IgE and skin prick test results, allergen-specific IgE antibodies and IgE antibodies against Ascaris in blood but not with allergic diseases except at the age of 10/12 years.