Last update:
29-Sep-2000

Arch Hellen Med, 17(1), January-February 2000, 52-60

ORIGINAL PAPER

Reference values of immunoglobulins
and complement factors
in children aged 1 day to 15 years

V. TZIMOULI,¹ F. KANAKOUDI-TSAKALIDOU,¹ A. GERMENIS,² T. KONSTANDINIDIS,³
Ch. TSANTALI,¹ V. DROSOU,⁴ V. KATSOUGIANNOPOULOS<sup>3

1</sup>1st Department of Pediatrics, Immunology Laboratory, Aristotle University, Thessaloniki,
²Department of Immunology and National Tissue Typing Center, General Hospital of Athens,
³Department of Epidemiology and Hygiene, Aristotle University, Thessaloniki,
⁴Department of Neonatology, Aristotle University, Thessaloniki, Greece

OBJECTIVE The determination of the reference values of immunoglobulins and complement factors in early infancy and during childhood.
METHOD Serum concentrations of all the above proteins were measured in 1946 apparently healthy children (971 boys and 1029 girls, aged 24 hours to 15 years) by rate nephelometry with the Behring Nephelometer Analyser (BNA). For accuracy and precision of the given results, we established our own control values and confidence limits. For statistical analysis, we calculated the 5th, 50th and 95th percentiles of serum concentrations for each group (males, females) at each age. Data were analyzed with the use of the SPSS software package.
RESULTS Concentrations were not affected by sex. They increased progressively by the 1st year with various rates and reached adult levels by different age. Findings regarding serum concentrations of immunoglobulins and subclasses confirmed those previously reported. For example the concentration of IgG and IgG1 decreased between the first 3rd–6th month and then increased again until the 3rd year. IgG3 reached the lowest concentration at the end of the 1st month and remained low until the age of 10 years. IgG2 and IgG4 concentrations were low during the first months and increased thereafter. IgA was undetectable by rate nephelometry at birth, but at three months of age it could be measured, remaining lower than adult levels during all childhood period. IgM concentrations increased rapidly, reaching adult reference values by six months. IgE, which was undetectable during early infancy, showed a wide variation of individual values after the age of one year. Concentrations of C3 and C4 corresponded to 50% of the respective adult reference values. During the following months, concentrations of these complement components increased rapidly reaching adult values by the third or sixth month of age.
CONCLUSIONS Our results indicate that adult reference values are not suitable to be used as reference values for any age period of childhood. For correct clinical interpretation of such proteins reference range of values corresponding to each year of age should be taken under consideration. We believe that our results describe the evolving pattern of the main serum proteins, that are measured in the pediatric practice for routine or research purposes.

Key words: Complement factors, Immunoglobulins, Reference values.