What do the IgE reactivity levels, classes, and ranges mean?

Reactivity level is the clinical interpretation of your test results. IgE reactivity is technically what is being measured in the lab, and where your results fall will help you understand the next steps. You may also see this described as “sensitization” from healthcare providers or on other allergy tests.

Classes provide an indication of the severity of a suspected allergen. Each result will fall in a class, and each of the classes will fall within a reactivity level.

Intensity ranges are the cut-offs that define the classes. These are specific to the instrument measuring your IgE concentration in the lab. You can learn more about the different ranges your results fall into on the printable PDF for your doctor, but more information is also below.

Our test is comparable to the RAST (Radio-Allergo-Sorbent Test), which is a standard IgE blood test performed by healthcare providers. The slight differences between our test and the standard RAST test are the ranges and units of measure. Labs use different methodologies for processing based on sample type, so it’s not uncommon for the ranges or units of measure to differ. As part of our CLIA-certified and CAP-accredited partner lab’s strict validation process, a comparison between dried blood spot to traditional venipuncture is performed to ensure a high correlation between the two.

Below is a table that can help you interpret your results in comparison to the RAST test:

Category / Interpretation Class Intensity Range (UOD) RAST Concentrations
Very Low 0 5-0 ≤ 0.35
Low 1 6-10 0.35 < x ≤ 0.7
Moderate 2 11-23 0.7 < x ≤ 3.5
High 3 24-45 3.5 < x ≤ 17.5
Very High 4 46-82 17.5 < x ≤ 50.0
Very High 5 83-163 50 < x ≤ 100
Very High 6 164-255 > 100

Our physician network will contact you as a courtesy if your results are high or very high (classes 3–6).

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