Document Type



Variability of the three major classes of immunoglobulins (IgA, IgG, and IgM) relative to sex and age must be considered to interpret accurately their serum concentrations. In the present study, analyses of seasonal changes in the mean and variance of immunoglobulin levels are reported for 3,210 unselected individuals from 5 to 94 years of age. Significant variation in mean immunoglobulin concentrations based upon date was not found. However, an important seasonal variability in the range of the serum levels was demonstrated.