Ultimate Allergy Screening (ALEX 2.0)

• Allergen extracts (measured, 117 according to the manufacturer): IgE to whole extracts of foods, pollens, mites, animal danders, moulds, insects and latex.
• Molecular components (measured, 178 according to the manufacturer): IgE to individual allergenic proteins, which helps separate primary sensitisation from cross-reactivity.
• Total IgE (measured): helps put specific IgE results in context. A high total IgE can be associated with many low-level positive results.
• CCD inhibition: a step in the method rather than a result, which reduces false-positive signals from cross-reactive carbohydrates.

The laboratory counts this panel as 295 allergens. Your report lists each allergen by name, with its result and the laboratory's cut-off for a positive value. The panel does not test for drug allergies, food intolerances (such as lactose intolerance), or non-IgE-mediated reactions.

How IgE allergy works

In IgE-mediated allergy, the immune system produces immunoglobulin E (IgE) antibodies against a normally harmless substance, such as a food protein or pollen. The IgE attaches to mast cells and basophils. On later exposure, the allergen cross-links this IgE and triggers the release of histamine and other mediators, producing symptoms within minutes to a couple of hours. These can range from hives and sneezing to breathing difficulty and anaphylaxis.

A blood test can detect IgE directed at a particular allergen. The World Allergy Organization stresses the difference between sensitisation, the presence of specific IgE, and allergy, which also requires clinically relevant symptoms when exposed to that allergen. A positive result alone does not establish allergy.

Extracts and molecular components

Traditional tests use whole allergen extracts, such as an extract of peanut or birch pollen, which contain many different proteins. Molecular (component-resolved) testing measures IgE to individual purified proteins. The EAACI Molecular Allergology User's Guide explains how this can help distinguish genuine primary sensitisation from cross-reactivity. For example, IgE to certain stable seed storage proteins in peanut has a different clinical meaning from IgE to peanut proteins that closely resemble birch pollen allergens, which more often cause milder mouth symptoms in people with hay fever.

Cross-reactive carbohydrates

Some IgE antibodies recognise carbohydrate structures (cross-reactive carbohydrate determinants, or CCDs) that are shared across many plants and insect venoms. These can produce positive results to numerous extracts that are rarely clinically important. ALEX² includes a CCD inhibitor in the sample diluent to reduce this effect.

What research shows about the platform

A 2018 study of an earlier ALEX version in 43 patient samples found good agreement with another established multiplex array at the level of molecular components, and the authors described it as a promising tool, particularly for people sensitised to many allergens. The authors noted that their findings were preliminary. Multiplex arrays are an adjunct to clinical assessment and are not a substitute for an allergy-focused history, skin testing or supervised food challenges where these are needed.

Each allergen is reported as a quantitative IgE level, usually alongside a class or a positive/negative cut-off defined by the laboratory. Higher levels for some components can be associated with a greater likelihood of clinical reactions, but no level reliably predicts how severe a reaction will be.

Reading a broad panel

• Expect some positives: testing almost 300 allergens at once makes it likely that some results will be positive without any clinical meaning. NICE advises that allergy tests should be interpreted in the context of an allergy-focused clinical history.
• A positive result is not a diagnosis: do not remove a food you eat comfortably because it shows as positive. Unnecessary avoidance narrows your diet without any benefit.
• A negative result is not clearance: do not reintroduce a food or exposure that has caused you a reaction because the result is negative. Some reactions are not IgE-mediated, and specialist assessment may still be needed.
• Cross-reactivity: component results can show that several positives share one underlying sensitisation, for example to a pollen protein found in related foods.

When to seek medical advice

If your results suggest sensitisation to a component associated with more serious reactions, or if you have had a reaction involving breathing, swallowing, collapse or widespread swelling, ask your GP about referral to an allergy service. If you have been prescribed an adrenaline auto-injector, keep carrying it regardless of your results.

Allergy symptoms are common, and identifying the trigger is not always straightforward, particularly when reactions occur to several foods or follow a seasonal pattern. A broad IgE profile can help you and a clinician narrow down which allergens deserve further investigation, and component results can help explain why someone with hay fever reacts to certain fruits or nuts.

NICE guidance on food allergy in children and young people advises that allergy testing is only carried out after an allergy-focused clinical history and that tests are chosen on the basis of that history. The same principle applies to adults. NICE also advises against using IgG food testing and alternative tests such as hair analysis or kinesiology to diagnose food allergy. This test measures IgE, not IgG.

This test may suit

• Adults with symptoms that suggest IgE-mediated allergy, such as hives, rhinitis, asthma symptoms or reactions shortly after eating
• People with several suspected triggers or possible pollen-food cross-reactivity
• People who cannot easily stop antihistamines, which interfere with skin prick tests but not with blood IgE tests

This test is not suitable for

• Anyone having a reaction now. Call 999 for anaphylaxis, for example if your throat feels tight or you are struggling to breathe or swallow.
• Deciding whether it is safe to eat a food you have reacted to
• Food intolerance, irritable bowel symptoms, drug allergy or delayed non-IgE reactions
• Children: please seek assessment through your GP or a paediatric allergy service
• Screening people without symptoms

Allergies can begin, change or fade at any age. Some people develop new allergies in adulthood, while some childhood food allergies are outgrown. Sensitisation patterns can also change over time, so a result describes the point at which the sample was taken. There is no evidence that broad allergy testing in people without symptoms improves long-term health, and this test is intended for people with symptoms to investigate.

• Antihistamines: you do not need to stop them. Blood IgE tests are not affected in the way skin prick tests are.
• Fasting: not needed.
• Specialist treatments: tell us if you receive allergen immunotherapy or anti-IgE treatment, as these can affect IgE levels and how results are read.
• Your history: before your appointment, note any reactions you have had, what you were exposed to, how soon symptoms began and what they were. This record is essential for interpreting the results.

Choose how your sample is taken when you book. We confirm the collection option, any collection fee and the expected turnaround time before you book.

• Juvenology Clinic, Maidstone (82 King Street, Maidstone ME14 1BH): Available.
• Partner clinic near you, anywhere in the UK: Available on request. We confirm availability for your postcode before you book.
• Postal home finger-prick kit: Ask before ordering. We offer a home kit only where the laboratory confirms this test is suitable for a finger-prick sample.

Sample: Venous blood sample (serum)

Collection notes: No fasting needed and antihistamines can be continued. Bring a written note of past reactions and suspected triggers. A home finger-prick kit is offered only if the laboratory confirms a capillary sample provides enough serum for the full array.

The price of this test covers laboratory analysis and the laboratory's results report. The report lists each result beside the laboratory's reference range.

Beyond the blood test: optional support, priced separately

• Personalised written interpretation report: £50
• General consultation: £50
• Results consultation (results discussion and follow-up advice): £100
• Personalised programme: from £150, after we assess whether a programme suits you

Consultations are with Marina, an NMC-registered nurse. She explains what your results show and how they relate to lifestyle. No prescription service is offered with these tests.

If a result suggests you need medical follow-up, we will recommend that you see your GP and, with your consent, can provide a letter to take with you. A blood test cannot rule out every condition. If you have symptoms, speak to your GP or NHS 111, and call 999 in an emergency.

If I test positive to a food, am I allergic to it?

Not necessarily. A positive result shows sensitisation. Whether that sensitisation matters depends on whether you have symptoms when you eat the food. Many people with positive results eat the food without problems.

Can this test replace a food challenge?

No. Where it is unclear whether someone is allergic, specialist allergy services may use supervised food challenges or other tests. A blood test cannot show that a food is safe.

What is the difference between this and an IgG food intolerance test?

This test measures IgE, the antibody involved in true allergy. NICE advises against using IgG testing to diagnose food allergy.

Will it show what is causing my bloating or tiredness?

Unlikely. These symptoms are rarely caused by IgE-mediated allergy, and positive results in this situation can be misleading.

How are results reported?

Your report lists every allergen tested with an IgE level and the laboratory's cut-off. Because the report is long, it can help to have it reviewed alongside your symptom history.

Is interpretation included?

The price covers laboratory analysis and the laboratory's report. You can add a personalised written interpretation report (£50) or a results consultation (£100). Where results suggest you need specialist allergy assessment, we will advise you to see your GP and, with your consent, can write to them.

1. Ansotegui IJ, et al. IgE allergy diagnostics and other relevant tests in allergy, a World Allergy Organization position paper. World Allergy Organization Journal, 2020;13(2):100080. https://doi.org/10.1016/j.waojou.2019.100080
2. Dramburg S, et al. EAACI Molecular Allergology User's Guide 2.0. Pediatric Allergy and Immunology, 2023;34(S28):e13854. https://doi.org/10.1111/pai.13854
3. Heffler E, et al. Extended IgE profile based on an allergen macroarray: a novel tool for precision medicine in allergy diagnosis. World Allergy Organization Journal, 2018;11:7. https://waojournal.biomedcentral.com/articles/10.1186/s40413-018-0186-3
4. Food allergy in under 19s: assessment and diagnosis (CG116). National Institute for Health and Care Excellence, 2011 (updated 2018). https://www.nice.org.uk/guidance/cg116/resources/food-allergy-in-under-19s-assessment-and-diagnosis-35109392795845
5. ALEX² Allergy Explorer product information. MacroArray Diagnostics, 2024. https://a.storyblok.com/f/164899/x/15491b7a11/20240223_web_madx_alex_flyer_210x250mm_en.pdf
6. Allergies. NHS. https://www.nhs.uk/conditions/allergies/