Published: July 2026
Medically reviewed by:
Anna Asarnoj, MD, PhD
Confident diagnostic decisions start with the right testing strategy
The goal of allergy diagnostics is to provide clinically relevant information that helps clinicians answer the relevant diagnostic question, establish an accurate diagnosis and guide appropriate patient management.
Today's allergy diagnostics offer laboratories a broader range of testing options than ever before. These include singleplex specific-IgE (sIgE) testing and multiplex molecular profiling.
Singleplex testing measures allergen-sIgE responses to individual allergens (both whole extracts and allergen components), providing highly sensitive, quantitative results. Multiplex testing simultaneously evaluates IgE responses to multiple allergens and typically provides semi-quantitative results. These approaches provide complementary information and serve distinct roles throughout the diagnostic pathway.1–4
As these approaches are based on different analytical platforms, it is important to recognise that results obtained using different commercial in vitro assays should not be directly compared or used interchangeably. Differences in assay design, allergen presentation and detection methodology affect test results, necessitating assay-specific interpretation. When laboratories adopt a different testing platform, assay-specific validation is required rather than applying common cut-offs or conversion factors.5–8
Therefore, the challenge is not choosing one technology over another but selecting the most appropriate diagnostic approach for each patient along the diagnostic pathway.
Importantly, detection of allergen-sIgE indicates sensitization but does not, on its own, confirm clinical allergy. Some patients are sensitized without developing symptoms, whereas others experience allergic reactions despite relatively low allergen sIgE concentrations. This also suggests that any positive or negative allergen-sIgE results needs to be interpreted based on the patient’s clinical history. Consequently, laboratory findings should always be interpreted alongside the patient's clinical history and physical examination to support accurate diagnosis and appropriate patient management.1–4,9
“A major challenge is patients who are referred to the specialist clinic following extensive IgE testing, where the test results, sometimes obtained several years before referral, have led to recommendations to avoid foods that the child has never eaten or had previously tolerated without symptoms.”
International guidelines recommend a clinically driven, stepwise approach in which the patient's clinical history directs laboratory investigations. Targeted testing using whole allergens is typically the first in vitro investigation when an IgE-mediated allergy is suspected. When additional diagnostic precision is required, component-resolved diagnostics (CRD) can help distinguish primary sensitization from cross-reactivity. Multiplex testing may provide broader molecular insight for selected patients with complex clinical presentations, including complex polysensitization, idiopathic anaphylaxis, or cases in which targeted investigations have not fully answered the clinical question.1–4,6
No single diagnostic approach is appropriate for every patient. Using the right test at the right stage of the diagnostic pathway enables laboratories to provide clinicians with results that are both clinically relevant and operationally efficient. A targeted, guideline-endorsed testing strategy also helps minimise clinically irrelevant findings, optimise resource utilisation and support more confident clinical decision-making.
* To be interpreted according to the patient's symptoms, clinical history and other results (skin tests, challenge tests, etc.) ** Clinical questions
Key takeaways for laboratories
Support clinicians by selecting laboratory investigations based on the patient’s clinical history.
Use targeted ImmunoCAP™ sIgE tests targeting whole allergens as the recommended first laboratory investigation when clinically relevant allergens are suspected.
Add component-resolved diagnostics when additional diagnostic precision is needed.
Consider multiplex testing for carefully selected patients with complex polysensitization, idiopathic anaphylaxis or when targeted investigations have not fully answered the clinical question.
Provide results that can be interpreted alongside the patient’s history to support confident clinical decision-making.
How singleplex diagnostics support the diagnostic pathway?
Quantitative results support confident clinical decisions
One of the principal strengths of singleplex testing is its ability to provide true quantitative sIgE values for allergen that support clinical decision-making.
ImmunoCAP sIgE tests quantify allergen-sIgE to whole allergens and allergen components with high analytical sensitivity, reliably measuring concentrations down to the lower limit of quantitation (0.1 kUA/L) because of excess allergen availability.10
Michael Thorpe et al. comprehensively reviewed the evidence on the clinical significance of low allergen sIgE concentrations (0.1-0.35 kUA/L), across multiple allergic triggers. In children with suspected peanut allergy, a 0.1 kUA/L cutoff achieved 100% sensitivity for Ara h 2. At the same time, in infants, it improved the detection of clinically relevant peanut sensitization from 97% to 100% with peanut extract and from 89% to 94% with Ara h 2. Similar findings were reported for hazelnut and walnut allergies, where a subset of clinically allergic individuals had sIgE levels between 0.1 and 0.35 kUA/L. Diagnostic benefits also extend to allergic triggers such as peach, cat, dog, drugs (rocuronium and suxamethonium) and wasp venom. Enhanced analytical sensitivity enables diagnosis in patients with a convincing history of reactions who would otherwise have been classified as seronegative.
Collectively, these findings indicate that low-level sIgE concentrations (0.1–0.35 kUA/L) may represent clinically significant sensitization and that optimal diagnostic thresholds should be selected based on the clinical context.10
Targeted allergy component testing enhances diagnostic clarity
When additional diagnostic precision is required following targeted ImmunoCAP sIgE testing with whole allergens, singleplex CRD may be sufficient if the patient's sensitization is driven by a small number of clinically relevant molecular allergen components.
For example, in cashew allergy, Ana o 3 is the major storage protein allergen. According to a study published in Allergy by Joanna Jerzyńska and colleagues, almost 82% of patients with severe Ana o 3-induced anaphylaxis were monosensitized to Ana o 3.11
This illustrates how CRD complements whole allergen testing by improving diagnostic confidence, helping clinicians answer specific diagnostic questions to support confident allergy diagnosis and management alongside the patient's clinical history.
Distinguishing primary sensitization from cross-reactivity
CRD improves diagnostic precision by helping distinguish genuine primary sensitization from clinically irrelevant cross-reactivity.
In food allergy, sensitization to profilins or PR-10 proteins may produce positive extract-based IgE results that do not necessarily indicate clinically relevant primary pollen or food allergies. When interpreted in the context of the patient's clinical history, targeted component testing helps distinguish genuine sensitization from cross-reactivity, thereby improving diagnostic accuracy and reducing the risk of unnecessary dietary restrictions.12
Another source of cross-reactivity is cross-reactive carbohydrate determinants (CCDs). CCDs are carbohydrate structures present on plant, insect venom and latex glycoproteins (but absent in humans), which induce anti-CCD IgE antibodies in approximately 20–25% of atopic individuals. Although IgE antibodies directed against CCDs can cause apparent sensitization to multiple Hymenoptera venoms and lead to false-positive allergen-sIgE results, they rarely have clinical relevance.13-15
Assessment of CCD-sIgE, for example using the ImmunoCAP™ allergen component o214 (MUXF3 CCD), can help identify patients in whom multiple venom-sIgE responses are attributable to CCD-mediated cross-reactivity rather than clinically relevant sensitization. In Hymenoptera venom allergy, component-resolved diagnostics using marker allergens—such as Ves v 1 and Ves v 5 for yellow jacket venom and Api m 1, Api m 3, Api m 4 and Api m 10 for honeybee venom—can identify the primary sensitizing venom in most patients. However, positive sIgE results to both honeybee and vespid venoms may still occur because of true double sensitization following exposure to multiple species or due to cross-reactivity between homologous venom proteins.
Consequently, interpretation of multiple venom sensitizations should integrate the clinical history, marker allergen profile and, when appropriate, CCD-sIgE results to distinguish clinically relevant sensitization from cross-reactivity.15,16
“In 25 years of pediatric practice, I've rarely needed multiplex microarray testing because, in most cases, a thorough clinical history is enough to guide targeted specific IgE testing. However, patients with multiple sensitizations and suspected but unclear symptoms to multiple triggers can benefit from multiplex microarray testing to map their sensitization patterns.”
Quantitative testing supports long-term patient management
The value of quantitative allergen-sIgE testing extends beyond diagnosis.
Birth cohort studies have shown that IgE reactivity to a limited number of allergen components in early childhood is associated with the subsequent development of asthma and allergic rhinitis, suggesting that selected component-sIgE responses may provide clinically useful prognostic information regarding future allergic respiratory disease.17,18
In addition, a longitudinal birth cohort study using repeated ImmunoCAP tests demonstrated that total IgE and allergen-sIgE could be followed from infancy through adolescence. Approximately 5 years onward, total IgE and overall allergen-sIgE followed parallel longitudinal trends, indicating that serial quantitative IgE measurements reflect changes in allergic sensitization over time. These findings suggest that longitudinal IgE assessment may have value for future risk evaluation, although further clinical validation is required.19
Where multiplex testing complements the diagnostic pathway
Multiplex testing enables the simultaneous detection of sIgE antibodies to multiple allergens in a single test, providing a broad molecular sensitization profile from a patient sample.1
Multiplex assays immobilise allergen molecules in very small quantities, offering both advantages and limitations. Their primary advantage is the ability to generate broad molecular sensitization profiles from minimal sample volumes, making them particularly valuable for complex multisensitized pediatric patients where sample volume is limited. However, due to the small amount of immobilized allergen some allergen-sIgE antibodies may remain unbound, while competing antibody isotypes, particularly IgG, can further reduce sIgE binding, potentially leading to underestimation of allergen-sIgE levels.2 This results in a narrower linear range and semi-quantitative, rather than fully quantitative, measurements.
For complex polysensitization and idiopathic anaphylaxis when conventional testing is inconclusive
Multiplex assays may provide additional clinical insight in selected complex clinical scenarios, particularly when patients present with complex polysensitization, idiopathic anaphylaxis or when targeted investigations have not provided sufficient diagnostic clarity.2
For example, in a multicentre cohort of patients with idiopathic anaphylaxis, multiplex testing using the ImmunoCAP™ ISAC E112i* assay identified nearly half of the allergen sensitizations that had not been detected in previous investigations.20
Supporting better patient outcomes
Laboratories play a central role in supporting accurate allergy diagnosis. Every testing decision influences the quality of information available to clinicians and, ultimately, the care patients receive. Effective allergy diagnostics is not about testing more— it is about using the right test at the right time. A stepwise approach that begins with a careful clinical history, followed by targeted quantitative ImmunoCAP sIgE testing using whole allergen extracts and allergen components, with multiplex molecular profiling reserved for clinically indicated cases, provides a balanced strategy for most patients. No single testing strategy is appropriate for every patient. Singleplex and multiplex assays should be viewed as complementary diagnostic tools, just as whole-allergen and allergen-component testing provide complementary clinical information. Understanding when to use each enables confident allergy diagnosis and management through a personalised, patient-centred approach.
Frequently asked questions
Singleplex testing measures sIgE antibodies to whole extracts or allergen components and provides quantitative results that support diagnosis, patient assessment and risk evaluation. Multiplex testing evaluates sIgE antibodies against multiple allergens simultaneously, providing a semi-quantitative broader molecular sensitization profile that can support selected complex clinical investigations.
International guidelines recommend targeted singleplex sIgE testing as the first laboratory investigation for most patients with suspected IgE-mediated allergy. It is particularly useful when the clinical history suggests specific allergen triggers or when quantitative allergen-sIgE measurements are required.
Multiplex testing may provide additional clinical insight in selected complex clinical scenarios, including complex polysensitization, idiopathic anaphylaxis or when targeted investigations have not fully answered the clinical question.
Yes. When initial extract-based allergy testing and targeted CRD do not fully explain the patient's sensitization profile or the clinical relevance of potentially cross-reactive allergens remains uncertain, a U-shaped diagnostic approach can be applied. This strategy begins with the conventional top-down approach (clinical history, examination and whole allergen-based testing, followed by allergen component testing) and, when diagnostic uncertainty persists, expands to a bottom-up approach using broader molecular sIgE panels. These are particularly useful for patients with complex polysensitization, helping to distinguish genuine sensitization from cross-reactivity, clarify the clinical relevance of sensitization patterns and guide therapeutic decisions such as allergen avoidance or allergen immunotherapy. The decision to proceed to broader molecular testing should be individualized based on the diagnostic outcome of the initial evaluation.2
Continue exploring allergy diagnostics
The ImmunoCAP allergy portfolio supports a guideline-driven approach to allergy diagnostics by providing quantitative sIgE testing, component-resolved diagnostics and multiplex solutions that help laboratories deliver clinically meaningful results. Understanding when to apply each approach helps laboratories support confident clinical decisions and better patient outcomes. Better allergy diagnosis is not about generating more data. It is about delivering the right information at the right time to support confident allergy diagnosis and management.
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