ALEX² Allergy Test (295 Allergens)

What is the ALEX² allergy test?

ALEX² (Allergy Explorer) is a multiplex allergy test that measures specific IgE antibodies to a large number of allergens at the same time from a single blood sample. The test covers a total of 295 allergens, made up of 117 allergen extracts and 178 molecular allergen components; in addition, the total IgE level in the blood is also measured. The panel covers a wide range of allergens, including foods, tree, grass and weed pollens, house dust mites, hair and dander from animals such as cats and dogs, molds, insect venoms and latex.

An allergen extract is prepared from the whole allergen source and shows general sensitization to that source. Molecular component analysis, on the other hand, looks at the individual proteins within the same source. Because some proteins are similar across different pollens and foods, a person may also test positive for an allergen they do not actually react to; this is called cross-reactivity. Component-level results can help distinguish true sensitization from cross-reactivity and allow the doctor to assess the characteristics of a possible reaction in more detail.

When is the ALEX² allergy test ordered?

Your doctor may order this test to investigate which allergens may be linked to symptoms that suggest an allergy. For people in whom sensitization to more than one allergen is suspected, whose symptoms change with the season or environment, or who cannot have skin testing, being able to examine a wide range of allergens from a single blood sample is a practical option.

• Allergic rhinitis (hay fever) symptoms such as sneezing, runny nose, nasal congestion and itchy eyes
• Symptoms that may be related to asthma, such as wheezing, coughing and chest tightness
• Skin symptoms such as hives, itching or eczema
• Itching in the mouth, abdominal pain or a skin rash after eating certain foods
• Reactions after a bee sting or contact with latex
• Situations where skin testing is not suitable because of widespread skin disease or medication use

The test can help in understanding which allergen a past reaction may have been linked to and support your doctor in planning avoidance advice. However, it is not used to assess an emergency. If a sudden, severe reaction develops, such as shortness of breath, swelling of the lips, tongue or throat, or fainting, call 112 without delay.

How do I prepare for the ALEX² allergy test?

No fasting is required for the test; the blood sample can be taken at any time of day. Antihistamine medications usually do not affect the measurement of IgE in the blood. For this reason, unlike skin testing, for which medication may need to be stopped some time in advance, there is often no need to stop allergy medication before the blood test. Even so, consult your doctor before stopping or changing any medication you take.

Telling our nurse during the appointment about the medications you take, any known allergies and any allergy tests you have had before makes the results easier to interpret. If you are receiving treatment such as allergy immunotherapy (allergy shots) or a biologic medication, please share this with your doctor as well; some treatments can affect how the results are interpreted. The blood sample is taken by a nurse at your home or workplace and analyzed in an accredited laboratory.

How are ALEX² allergy test results interpreted?

The results report shows the specific IgE level measured for each allergen and the total IgE value. Detecting specific IgE to an allergen shows that the body has become sensitized to that allergen; however, this alone does not mean a diagnosis of allergy. Some people who are sensitized may have no symptoms at all when they are exposed to that allergen.

For this reason, the results should be evaluated together with your symptoms and medical history by your doctor and, if necessary, by an allergist. Molecular component results can help interpret whether a positive result is due to cross-reactivity. You are advised not to remove a food or food group from your diet on your own based on the results; unnecessary restrictions can have a negative effect on your nutrition. A negative result does not rule out every allergy either, because some reactions can occur through mechanisms other than IgE. Reference limits may vary between laboratories.