Reference intervals for serum IgG, IgA, IgM, C3, and C4 as determined by rate nephelometry

Area of Science:

• Clinical immunology
• Pediatric reference ranges

Background:

• Accurate reference intervals for immunoglobulins (IgG, IgA, IgM) and complement proteins (C3, C4) are crucial for diagnosing immune deficiencies.
• Previous studies often relied on immunodiffusion methods, which may differ from modern techniques.

Purpose of the Study:

• To establish current reference intervals for IgG, IgA, IgM, C3, and C4 in a healthy pediatric and adult population.
• To compare findings with previously established ranges and identify discrepancies, particularly regarding age-related attainment of adult levels.

Main Methods:

• Rate nephelometry was employed to determine protein concentrations.
• Data were collected from a cohort of 750 well children and 120 healthy adults.

Main Results:

• Reference intervals for IgG, IgA, IgM, C3, and C4 were successfully established for the study population.
• The generated ranges generally align with existing immunoglobulin data.
• Some differences were noted concerning the specific ages at which adult immunoglobulin levels are typically achieved.

Conclusions:

• The study provides updated reference intervals for key immunoglobulins and complement proteins using a modern assay.
• Findings support the general agreement with prior research but highlight nuances in pediatric development of adult immune protein levels.