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Background: The reference values for total serum IgE are accepted to vary according to the geographical area involved. In 1981 we published the reference values for a donor population in the city of Valencia (Spain) and its metropolitan area. Since then, we have noted an increase in the prevalence of asthma and rhinitis in countries with a Western lifestyle, including Spain., Aim: To update the adult reference values for total serum IgE in the city of Valencia and its metropolitan area, and to determine their diagnostic usefulness in asthma and allergic rhinitis., Material and Methods: We studied two groups of 69 and 100 individuals each. One group comprised apparently healthy blood donors, as assessed by a routine blood bank study protocol and the application of a questionnaire to exclude perceived allergic or parasitic diseases, while the other group consisted of individuals with atopic respiratory disease (bronchial asthma and allergic rhinitis) studied in our service in the same time period (spring 2004). Total serum IgE was determined by the UniCAP method developed by Pharmacia., Results: The geometric mean of total serum IgE among blood donors was 46.65 kU/l (95% CI: 15.5-77.8) versus 204.29 kU/l (95% CI: 93.3-515) among allergic subjects. The difference between the two groups was statistically significant. No significant difference was found between our donor sample in 1981 and the sample in the present study. Establishing an arbitrary cut-off point of 1.65 standard deviations (SD)(equivalent to 95 % of the donor population), we obtained a figure of > 183 kU/l whereby 44% of all allergic individuals presented a value below this cut-off point. To practical effects, these allergic patients behaved as low responders (LRs) in relation to total IgE, whereas the remaining individuals were high responders (HRs) in relation to total IgE., Conclusions: Our data confirm the current validity of the reference values obtained in 1981, which continue to be significantly different from those of the UniCAP method for Swedish donors. The population of allergic subjects can be divided into two subgroups: subjects with total IgE levels similar to those of the donors, which we refer to as LRs, and which represent 44% of all allergic subjects, and a second subgroup with total IgE values above those of the donors (HRs), who would therefore be the only subjects that would be identified by individual serum IgE study.

A limited survey on the allergic status and total IgE was performed on 205 persons of Turkish origin aged between 16 and 76 years living in Stockholm, Uppsala, Sweden in 1990. A questionnaire was mailed to 205 persons and was returned by 92%. 71 persons were randomly selected among those who returned the questionnaire, and were examined after an interview, skin-prick test (SPT) and total IgE levels were also measured. The atopy prevalence of the randomly selected group of Turks was found 32.4%. Clinical symptoms were significantly associated with positive SPT reactivity. IgE levels in the atopic group were significantly higher than those of non atopic group (78.2 ku/l vs 28.4 ku/l respectively). However, the difference in IgE levels were significant between non atopic and atopic groups residing in Sweden longer than 10.5 years, but not significant between those who resided less than 4.5 years. The allergic spectrum changed with residence time spent in Sweden in Turks. Skin test positivity to birch, cat, and dog increased with time. This increase may be related to the change in life styles and habits, such as indoor contact with pets, and intensive environmental birch pollen exposure. In conclusion, our data indicate that immunologic status of persons is influenced by a new millieu. Within a few years the allergic status of Turkish immigrants adapted to the new environment.