Expected Values
Note! Good practice recommends that each laboratory establishes its own range of values.
Comparison studies between Pharmacia CAP System IgE FEIA and ImmunoCAP Total IgE have been performed with 151 samples in two replicates on three occasions. The results show good agreement between the methods.
An expected values study* was performed with ImmunoCAP Total IgE on serum collected from 63 non-atopic blood donors. The results of this study (Geometric Mean = 17.4 kU/l, and Geometric Mean +2SD = 113 kU/l) confirm the applicability of results from previously published expected values studies (1) performed with patient sera from a carefully selected non-atopic patient population using Phadebas IgE PRIST in vitro assay technology.
Since previous studies have shown good agreement between results obtained with Pharmacia CAP System IgE FEIA and Phadebas IgE PRIST, the expected values for Phadebas IgE PRIST can be used for ImmunoCAP Total IgE.
Adults
Total IgE levels have been determined using Phadebas PRIST in serum from 412 adult patients with respiratory symptoms, of which 160 were classified as non-atopic and 252 had atopic disease, and showed the following distribution pattern between atopic and non-atopic individuals (2): below 25 kU/l – 84% non-atopic, above 100 kU/l – 78% atopic.
When determined in another study using Phadebas IgE PRIST (4,5), the geometric mean calculated from the total IgE levels in serum of 175 non-atopic adults was 13.2 kU/l, + 2SD = 114 kU/l.
Children
The data from two independent studies using Phadebas IgE PRIST for determination of total IgE in serum from 466 carefully selected healthy children have been used for calculations leading to the following summary of development of serum total IgE levels during childhood (3).
After the peak at the age of 10, serum total IgE levels have reached adult values.
| Age | Geometric
mean
(kU IgE/l) | + 1 SD
(kU IgE/l) | Age | Geometric
mean
(kU IgE/l) | + 1 SD
(kU IgE/l) |
|---|
| Weeks | | | Years | | |
| 6 | 0.6 | 2.3 | 2 | 5.7 | 23 |
| Months | | | 3 | 8.0 | 32 |
| 3 | 1.0 | 4.1 | 4 | 10 | 40 |
| 6 | 1.8 | 7.3 | 5 | 12 | 48 |
| 9 | 2.6 | 10 | 6 | 14 | 56 |
| 12 | 3.2 | 13 | 7 | 16 | 63 |
| | | | 8 | 18 | 71 |
| | | | 9 | 20 | 78 |
| | | | 10 | 22 | 85 |
It is recommended that each laboratory establishes its own expected range of values. (3)
Interpretation of Results
IgE calibrators, traceable to the WHO preparation 75 / 502 for Human IgE, are used for the determination of total IgE and values are expressed in kU/l.
High levels of circulating total IgE antibodies are usually associated with allergy.
Measuring total IgE levels
- provides valuable information about the level of the total IgE load provides a valuable overview of the patient’s atopic status
- in occupational allergy, the test indicates a status that might not be associated with common allergens and that more specific allergy investigation is therefore needed.
The serum concentration of total IgE is age-related. At about 10 years of age, serum total IgE reaches values that are maintained during adult life (3).
*Studies performed at Pharmacia & Upjohn Diagnostics AB, Uppsala, Sweden.
References:
- Björksten B, Weeke B. Annual meeting of the European Accadamy of Allergy and Clinical Immunology, 1995. Allergy 1985;40 (suppl 4).
- Zetterström O Johansson SGO. IgE concentrations measured by Phadebas IgE PRIST in serum of healthy adults and in patients with respiratory allergy. Allergy 1981;36:537-547.
- Johansson S.G.O., Yman L. In Vitro Assays for Immunoglobulin E. Clin Rev Allergy 1988;6(2):93-139.
- Bhalla RB et al. Advance interpitation of clinical laboratory data. Bensen AA, Ed. New York: Marcel Dekker Inc, 1982;292-305.
- Kjelman N-IM, Johansson SGO, Roth A. Clin. Allergy 1976;6:51-59.