Total immunoglobulin concentrations in normal individuals are influenced by a number of factors including age, gender and ethnic background . In general, immunoglobulin levels are lower when young and increase into adulthood. The exception is IgG in newborn infants: placental transfer of IgG results in high neonatal serum concentrations (near adult levels) that persist for several months after birth.
Significant ethnic differences in immunoglobulin concentrations have been observed. Black Africans have higher levels of IgG and IgM but similar levels of IgA compared with Caucasian populations . Gender may also influence immunoglobulin concentrations and significant differences in IgM reference intervals for males and females have been reported .