Serum immunoglobulin levels in healthy children and adults.

Serum levels of IgM, IgG and IgA were determined in 270 healthy children, 4–12 years old, and in thirty healthy adults by the radial immunodiffusion method of Mancini. There were nine 1-year age groups of thirty children each (fifteen boys and fifteen girls); the adult group consisted of fifteen males and fifteen females. The difference in values between adults and children was statistically significant. The IgG and IgA concentrations showed a gradual rise with increasing age; the IgM concentration remained constant at a distinctly lower level than that in adults. The IgA level was about the same in both sexes. Girls had significantly higher IgM and IgG levels than boys. A consistent seasonal influence on the three serum immunoglobulin concentrations could not be demonstrated. A very wide variation in serum levels of each immunoglobulin in each age group was found. Very low values were by no means exceptional. The consequence of this finding for the diagnosis of immunological incompetency is discussed.