D3.332 - Determination of Reference Intervals for IgG, IgA, and IgM Levels by Age in Healthy Adults

Serum immunoglobulin level determination is frequently used in clinical practicebecause it is useful in the diagnosis of immunodeficiencies and the identification of variousinfections and immune conditions. Clinical laboratories typically use the reference rangesspecified in the manufacturer's kits; however, immunoglobulin levels can vary based onpopulation characteristics such as region, age, sex, and exposures. Therefore, the aim of thisstudy is to establish new age-specific immunoglobulin reference ranges for our population.

The study included 305 individuals aged 18-65 years. Serum IgG, IgA, and IgMlevels were measured using the nephelometric method in a total of 5 groups, each consistingof 61 individuals. Based on the obtained data, new reference ranges were calculated for thedetermined age groups using a 95% confidence interval. These reference ranges werecompared with the manufacturer's own values and literature data. The effects of age, sex,smoking and alcohol exposure, and urban-rural living factors on immunoglobulin levels wereinvestigated.

The age-independent reference ranges for serum IgG, IgA, and IgM parameters werecalculated as 11.8-12.3, 2.04-2.24, and 1.07-1.21, respectively. While IgG and IgA levels didnot show significant changes with age, it was observed that IgM levels decreased with age.There was no effect of gender on IgG and IgA levels, whereas IgM levels were found to behigher in men than in women. IgG and IgM levels were lower in smokers compared to non-smokers. Alcohol consumption, body mass index, and urban-rural living factors did not causesignificant changes in any of the three immunoglobulin levels.

The data from our study were found to be different when compared to otherstudies in the literature and the manufacturer's reference values. This difference was attributedto regional variations. As a result, our study provides useful regional data on the changes inserum immunoglobulin values based on age, sex, alcohol and smoking exposure, and urban-rural living characteristics.

While IgG and IgA levels do not show significant changes with age, IgM levels were observed to decrease with age.

When analyzed by gender, it was found that IgM levels in male individuals were significantly higher than in female individuals. Each laboratory should determine its own reference ranges for its local population.If the evaluated parameter is affected by variables such as age, gender, and environmental factors, it would be beneficial to classify and determine reference ranges accordingly.