Skip to main content

Component-resolved allergy testing (ISAC / ALEX) - high-risk vs low-risk, on one blood sample.

For children and adults where standard IgE testing does not tell you enough about risk. A consultant allergist, one blood sample, and hundreds of individual protein components analysed to separate high-risk from low-risk sensitisation.

A radiographer guides a patient onto the bed of an advanced 3 Tesla MRI scanner in a London imaging suite

Indicative pricing

What private component-resolved allergy testing costs in the UK.

In short

Component-resolved testing: £350–£700, results back in 7–14 days.

ItemIndicative range
Allergy consultation and interpretation£250–£450
ISAC 112 test£350–£550
ALEX2 test (295 components)£450–£700
Targeted single components (per allergen)£60–£120
Combined skin prick + component£500–£900
Follow-up interpretation review£150–£280
Written management planIncluded

The problem

Risk-stratify the story, on one blood sample, with a consultant interpreting.

  • The story your standard IgE cannot tell

    Component testing separates high-risk primary sensitisation from cross-reactive pollen sensitisation - the risk conversation changes.

  • One blood sample, hundreds of proteins

    ISAC and ALEX platforms measure IgE to individual allergen molecules on a single blood draw.

  • A consultant interpreting, not a lab print-out

    Component results are only useful when read against the history - you need an allergist, not just a report.

When it helps

When component-resolved allergy testing is the right step.

  • Peanut allergy risk stratification

    Ara h 2 positive is high-risk; Ara h 8 alone often indicates pollen cross-reactivity.

  • Tree nut cross-reactivity

    Hazelnut Cor a 14 versus Cor a 1 - very different risk profiles.

  • Wheat allergy vs pollen cross-reactivity

    Tri a 19 (omega-5 gliadin) matters for wheat-dependent exercise-induced anaphylaxis.

  • Shellfish

    Tropomyosin vs other components changes the cross-reactivity story.

  • Pollen-food syndrome

    PR-10, LTP and profilin patterns explain fruit and vegetable oral itching.

  • Latex-fruit syndrome

    Hev b component pattern in latex-allergic patients.

  • Insect venom allergy

    Species-specific components separate true bee vs wasp allergy from cross-reactivity.

  • Red flag: multiple positive foods with unclear history

    A conversation with a consultant, not a broader panel.

Options

When component testing outperforms skin prick and standard IgE.

  • ISAC 112

    112 components on a microarray - the classic component test.

  • ALEX2 (Macro-Array)

    295 components including extracts - often the newer choice.

  • Single-component ImmunoCAP

    Individual components (e.g. Ara h 2, Cor a 14) - targeted and cheaper.

  • Basophil activation test (BAT)

    Functional test - used in specialist centres for complex cases.

  • Skin prick with fresh food

    Prick-to-prick for foods poorly represented in extracts.

  • Oral food challenge

    The definitive test when component testing is equivocal.

  • Tryptase baseline

    To exclude mastocytosis in unexplained anaphylaxis.

  • Written interpretation with plan

    The whole point - component testing is only useful with an interpretation.

Safety and recovery

What to expect - honestly.

  • It is just a blood test

    The test itself carries only the risks of a standard blood draw.

  • Component testing can be over-interpreted

    A positive minor component without matching history is not an allergy - it needs a consultant read.

  • Cost adds up

    Broader panels are expensive; a targeted single component often does the job.

  • Turnaround is 1–2 weeks

    Not a same-visit test - plan around holidays and school challenges.

  • Not a screening test

    This is for stratifying a specific story, not "checking for allergies".

  • Complements skin prick

    Often used alongside skin prick, not instead.

  • Not for delayed reactions

    Delayed food-protein reactions and contact dermatitis need patch testing.

  • Insurance coverage varies

    Some insurers cover component testing on written medical justification.

  • Red flag: airway swelling, breathlessness or collapse

    Adrenaline first, 999 second. Every family with a diagnosed allergy needs to be clear on this.

Your notes

Your report in four parts.

A UK consultant reviewing notes
  1. Header

    Platform used and components measured

    Whether ISAC, ALEX or targeted ImmunoCAP was used.

  2. Technique

    Component pattern

    IgE levels to each relevant component, in context.

  3. Findings

    Risk stratification

    What the pattern means - primary sensitisation vs cross-reactivity.

  4. Impression

    Plan and next steps

    Read this first: strict avoidance, ladder, challenge or no action.

Recognised by major UK insurers

BupaAXA HealthVitalityAvivaWPACignaHealixBupaAXA HealthVitalityAvivaWPACignaHealixBupaAXA HealthVitalityAvivaWPACignaHealix

Paediatric allergy is available on the NHS but 6–18 months waits are typical for a first specialist appointment; it is usually covered by private insurers when medically indicated.

Frequently asked

Everything we get asked about component-resolved allergy testing.

  • When is component-resolved testing worth doing?

    When standard skin prick or specific IgE is positive but the history is unclear, when peanut or tree nut risk needs stratifying before an oral challenge or nursery start, or when a patient is sensitised to multiple foods with confusing history.

  • What does the test involve?

    A single blood sample sent to a specialist lab. ISAC uses a microarray of 112 components; ALEX2 covers 295 components including whole extracts. Results are read alongside your allergy history by a consultant allergist.

  • How much does component-resolved testing cost privately in the UK?

    Roughly £350–£550 for ISAC, £450–£700 for ALEX2 and £60–£120 for targeted single components. The consultation is a separate £250–£450.

  • Is component-resolved testing available on the NHS?

    Yes, in tertiary paediatric and adult allergy centres, but access is patchy and typically reserved for complex or high-risk cases.

  • Do I still need skin prick testing if I have this done?

    Often yes - skin prick and component testing answer different questions and are frequently used together, especially before an oral food challenge.

  • Do we need to stop antihistamines?

    No - component testing is a blood test and is not affected by antihistamines. Only skin prick testing needs antihistamines stopped.

Related treatments

Looking for something else?