ImmunoCAP Phadiatop is a blood test designed to differentiate between atopic and non-atopic patients. Results indicate high or low probability for atopy. A negative result indicates that the symptoms are not caused by common environmental allergens, and the physician may explore other possibilities.
In younger children aged 0-3, allergic sensitization is mostly related to food allergens (such as egg, milk, fish, soybean and peanut) rather than inhalant allergens. However, antibodies to inhalant allergens such as house dust mites and pets can still appear early in life. With this in mind, a combination of Phadiatop and the most common food allergens is recommended when testing children for atopy.
Clinical value
Phadiatop and Phadiatop Infant are assays for the graded determination of atopy with semiquantitative or qualitative results.
Semiquantitative results
Phadiatop results are expressed as Phadia Arbitrary Units/l (PAU/l) indicating degree of sensitization. A Phadiatop PAU/l value above the limit of quantification indicates that the patient is atopic (positive), i.e. measurable levels of specific IgE antibodies to common inhalant allergens have been detected. A Phadiatop PAU/l value below the limit of quantification indicates that the patient is non-atopic (negative), i.e. the level of specific IgE antibodies is undetectable. Higher Phadiatop PAU/l values indicates a higher degree of sensitization, i.e. higher levels of specific IgE antibodies to common inhalant allergens.
Qualitative results
Phadiatop results are expressed as positive or negative. A positive Phadiatop result indicates that the patient is atopic, a negative result indicates that the patient is non-atopic, i.e. not sensitised to inhalant allergens. In order to determine the concentration of allergen specific IgE antibodies, it is recommended to retest the sample with the appropriate ImmunoCAP Specific IgE allergens.
The following clinical results were obtained from clinical trials including 836 patients with suspected allergy:
Final diagnosis
Atopy/non-atopy | ImmunoCAP Phadiatop results |
| Positive | Negative | Total |
| Atopy |
483 |
38 |
521 |
| Non-atopy |
34 |
281 |
315 |
| Total |
517 |
319 |
836 |
- Sensitivity 93%
- Specificity 89%
All tests were run using the 0.35 kU/l specific IgE calibrator as cut off.
Specimen collection and preparation
- Serum and plasma (EDTA or heparin) samples from venous or capillary blood can be used
- Collect blood samples using standard procedures
- Keep specimens at room temperature (RT) for shipping purposes only
- Store at 2–8 °C up to one week, otherwise store at –20 °C
- Avoid repeated freezing and thawing
Important note
As in all diagnostic testing, a definitive clinical diagnosis should not be based solely on the results of a single test method. A diagnosis should be made by the physician after evaluation of all clinical and laboratory findings.