Reference values of total serum IgE and their significance in the diagnosis of allergy among the young adult Kuwaiti population

Background The reference total serum immunoglobulin (IgE) values and the us efulness of total IgE values in the diagnosis of allergy have not been esta blished for the Kuwaiti population. The literature reference values may not be applicable since such values often vary among ethnic nationalities. Objective The aim of this study was to establish the reference IgE values f or the young adult Kuwaiti population and to determine the usefulness of su ch values in the diagnosis of allergic diseases in the community. Methods A total of 1057 randomly selected young adults were screened for at opy using the Pharmacia CAP-Phadiatop(R) method. Atopy was detected in 423 individuals (40.0%). Total serum IgE was then measured in 542 randomly sele cted Phadiatop-negative (non-atopic) cases in the age range 18-50 years (me an 28.9 years) and male:female ratio of 1.3. Results Serum total IgE values in non-atopics covered a very wide range (< 2-1993 kU/L) with a geometric mean (GM) value of 43.7 kU/L. The reference r ange, calculated as the 95% confidence interval of the log IgE (95% CI) was 3.2-602.5 kU/L, The 90% CI was 11.7-162 kU/L. The GM was significantly hig her for males than females, (53.7 vs. 35.5 kU/L, P < 0.001) and for smokers than non-smokers, (64.6 vs. 40.7 kU/L, P < 0.01), but was independent of a ge. Although the GM for the non-atopics (43.7 kU/L) was significantly lower than those of the asymptomatic atopics (213.8 kU/L) and allergic asthmatic s (626.6 kU/L), the 95% CI for the three groups showed considerable overlap . Conclusions These results show that the normal total IgE values in the youn g adult Kuwaiti population are generally high and that the distribution of the values is so wide that the diagnostic value of total serum IgE in this community is likely to be very limited.