Range of normal serum immunoglobulin (IgG, IgA and IgM) values in Nigerians.

: The serum levels of immunoglobulins G, A and M of 703 apparently healthy Nigerians resident in Ibadan and aged 1-50 years were studied. The differences in values that are related to age, sex and season were also computed. Normal values of the immunoglobulins varied with age and sex. IgG mean values for the different age groups ranged from 688 to 1251 mg/100 ml in the males and from 720 to 1038 mg/100 ml in the females. For the IgA class the mean values ranged from 81 to 211 mg/100 in the males and from 90 to 206 mg/100 ml in the females. Mean values of IgM varied from 65 to 132 mg/100 ml in the males and from 96 to 114 mg/100 ml in the females. There was a general increase in IgG levels with advancing age especially in the first 20 years of life. IgA increased progressively with age from 1 to 50 years. The male IgM levels generally rose with increasing age while there was no significant elevation in female IgM values. Females had higher levels of IgG, IgA and IgM in the first 10-20 years of life after which the levels were either the same or higher in the males. The possible reason for this observation is discussed. A significant seasonal influence on the three immunoglobulin concentrations could not be demonstrated.