Allergy Component Testing (CRD)

What is the Allergy Component Testing (CRD Test)?

The Allergy Component Testing (CRD Test) is an advanced blood test that helps identify specific allergenic components responsible for allergy symptoms. CRD stands for component resolved diagnostics, which means the test looks deeper than whole allergen extracts and checks for immune response to individual allergen proteins.

The test is performed on a serum sample collected from your blood. It uses Multiplex Nanotechnology Assay (4th Generation) to measure specific IgE antibodies against a wide range of allergen extracts and molecular allergen components.

Doctors may recommend this test if you have complex, repeated or severe allergy symptoms, food reactions, respiratory allergy symptoms, suspected cross reactions, insect venom allergy, latex allergy or unclear allergy triggers.

What Does an Allergy Component Testing (CRD Test) Measure?

The Allergy Component Testing (CRD Test) helps your doctor understand your allergy pattern in greater detail:

• Specific IgE response: Measures IgE antibodies against multiple allergen extracts and molecular components
• Pollen allergy pattern: Checks for sensitisation to grass, tree and weed pollen allergens
• Mite allergy pattern: Assesses house dust mite and storage mite related allergens
• Food allergy pattern: Evaluates plant based foods, milk, egg, fish, seafood, meat, nuts, seeds, grains, legumes, fruits and vegetables
• Insect and venom sensitivity: Checks allergens related to ant, bee, wasp and cockroach exposure
• Fungal and yeast sensitivity: Assesses response to fungal spores and yeast related allergens
• Animal related allergy pattern: Measures response to pet and farm animal epithelial tissue allergens
• Latex and other allergens: Helps assess latex, Ficus, CCD, parasite related and other allergen groups
• Cross reaction assessment: Helps differentiate true allergy from cross reactive sensitisation in selected cases

Allergy Component Testing (CRD Test): Who Needs It and Why It’s Done

What Symptoms May Call for an Allergy Component Testing (CRD Test)?

Doctors may advise this test if you have symptoms such as:

• Repeated sneezing, blocked nose or runny nose
• Wheezing, cough or breathlessness
• Itchy eyes, watery eyes or throat irritation
• Skin rashes, hives or itching after exposure to certain triggers
• Swelling of lips, face, tongue or throat after food or insect exposure
• Stomach pain, vomiting or diarrhoea after suspected food allergy
• Recurrent reactions after eating nuts, milk, egg, seafood, wheat or other foods
• Symptoms after contact with pets, pollen, dust, mould, latex or insect stings
• Severe allergic reactions or suspected anaphylaxis
• Multiple suspected allergies where the exact trigger is unclear

Who Should Get an Allergy Component Testing (CRD Test)?

• People with complex allergy symptoms involving more than one trigger
• People with suspected food allergy or multiple food reactions
• People with respiratory allergies such as asthma or allergic rhinitis
• People with suspected pollen, mite, pet, mould, venom or latex allergy
• People with unexplained or repeated allergic reactions
• People being considered for allergen immunotherapy
• People who need help distinguishing primary allergy from cross reaction
• People who need a more detailed allergy profile after basic allergy testing
• People whose symptoms do not clearly match earlier allergy test results

Why is an Allergy Component Testing (CRD Test) Done?

The Allergy Component Testing (CRD Test) is done to identify allergenic components that may be linked to your symptoms. It helps your doctor understand whether your allergy is likely to be a true primary allergy, a cross reaction or a low level sensitisation that may not be clinically important.

Importance of Allergy Component Testing (CRD Test)

The Allergy Component Testing (CRD Test) is important because some allergy symptoms are caused by specific proteins within an allergen, not just the whole allergen source. For example, two people may both test positive to a food or pollen, but their clinical risk may differ depending on which component is positive.

This test can support more precise allergy management, dietary advice, allergen avoidance planning and decisions about immunotherapy. It is especially useful in people with multiple positive allergy results, suspected cross reactions or severe reactions where a more detailed allergy profile is needed.

A positive result shows sensitisation, but it does not always mean that the allergen is definitely causing your symptoms. Your doctor will interpret your results with your symptoms, exposure history and clinical examination.

Allergy Component Testing (CRD Test) Booking and Reports: Metropolis Healthcare

How to Book the Allergy Component Testing (CRD Test) and Get Your Reports?

1. Simple Online Booking
   Booking can be done through the Metropolis Healthcare App or website. Select the Allergy Component Testing (CRD Test), choose a convenient time slot, and provide your address for a blood test at home. You can also visit the nearest Metropolis Lab if you prefer to give the sample directly at the lab.
2. Safe Home Sample Collection
   Our trained phlebotomists ensure timely collection of your sample while strictly following all safety and hygiene protocols.
3. Sample Tracking Updates
   Stay informed at every step. From collection to testing, you can track your sample directly through the Metropolis Healthcare website.
4. Accurate Laboratory Testing
   Your sample is processed at NABL and CAP accredited laboratories, where expert technicians ensure accurate results.
5. Quick and Easy Reports
   Receive your test reports promptly via email, WhatsApp, or by downloading them directly from the Metropolis Healthcare website or app.

Is Home Sample Collection for Allergy Component Testing (CRD Test) Available Near You?

Yes, Metropolis Healthcare offers home sample collection for Allergy Component Testing (CRD Test). This service saves you time, reduces the need for travel, and ensures professional sample handling while maintaining strict quality standards.

In how much time will I get Allergy Component Testing (CRD Test) report?

Reports are usually available on the same day once the sample reaches the lab.

Note: Reporting time may vary based on your location.

Where can I see or get Allergy Component Testing (CRD Test) results?

Test results from Metropolis Healthcare can be accessed through multiple convenient channels. You can log in to the Metropolis website using your credentials or use the Metropolis Healthcare App to view and download your reports. Additionally, test reports are sent via email or WhatsApp and you also have the option to collect a physical copy directly from the lab.

Interpreting Allergy Component Testing (CRD Test) Results

Understanding abnormal Allergy Component Testing (CRD Test) results by parameter

A positive result shows sensitisation, but it does not always confirm that the allergen is causing your symptoms. Your doctor will connect the result with your symptoms, exposure pattern, reaction severity, and medical history.

How Should You Prepare for an Allergy Component Testing (CRD Test)?

The Allergy Component Testing (CRD Test) needs simple preparation. Follow these instructions before your sample collection:

• Preferably fasting: A fasting sample is preferred, but it is not mandatory. Follow your doctor’s advice.
• Share clinical history: Tell your doctor about your allergy symptoms, past reactions, suspected foods, environmental triggers and insect sting history.
• Mention severe reactions: Inform your doctor if you have had swelling, breathing difficulty, fainting or anaphylaxis.
• Medication review: Inform your doctor about all medicines, allergy medicines, inhalers, steroids, immunotherapy and supplements you are taking.
• Do not stop medicines on your own: Continue or stop medicines only as advised by your doctor.
• Normal hydration: Drink water as you usually do before the test.
• Carry previous reports: Bring earlier allergy test reports, food reaction records, asthma reports or hospital notes if available.

How Is an Allergy Component Testing (CRD Test) Done? (Step-by-Step Procedure)

• Preparation: A tourniquet is tied around your arm to make veins more visible.
• Cleaning:The puncture site is cleaned with antiseptic.
• Sample Collection
  A sterile needle is used to draw about 3 ml of blood into a gel vacutainer.
• Completion: The needle is removed, and a bandage is applied to the site.
• Processing: The serum sample is tested using Multiplex Nanotechnology Assay (4th Generation) to measure specific IgE antibodies against allergen extracts and molecular components.

Conditions That May Affect Allergy Component Testing (CRD Test) Accuracy

Certain patient related and clinical factors can influence how your CRD results are interpreted:

• Recent allergen exposure: Results are more meaningful when matched with your recent food, pollen, dust, pet, mould, latex or insect exposure.
• Cross reactive proteins: Some allergen components are shared across different foods, pollens or natural sources and may cause cross reactive results.
• CCD reactivity: Cross reactive carbohydrate determinants can sometimes contribute to broad sensitisation patterns.
• Allergen load: Heavy or repeated exposure to an allergen may influence symptom severity and clinical relevance.
• Age and atopy: Your age and tendency to develop allergic conditions can affect how results relate to symptoms.
• Previous reaction history: A positive result is more useful when it matches your actual reaction pattern.
• Treatment history: Ongoing allergy treatment or immunotherapy should be shared with your doctor for correct interpretation.

Diseases That an Allergy Component Testing (CRD Test) Can Help Detect

• IgE Mediated Food Allergy: Allergy to foods such as nuts, milk, egg, seafood, wheat, fruits, vegetables or other foods
• Allergic Rhinitis: Sneezing, runny nose, blocked nose and nasal itching linked to allergens
• Allergic Asthma: Wheezing, cough and breathlessness triggered by allergens
• Pollen Allergy: Allergy symptoms related to grass, tree or weed pollen exposure
• Dust Mite Allergy: Allergy linked to house dust mites or storage mites
• Fungal Allergy: Allergy related to moulds, fungal spores or yeast allergens
• Pet Allergy: Symptoms triggered by cat, dog, horse or other animal allergens
• Insect Venom Allergy: Allergy related to bee, wasp, hornet or ant venom components
• Latex Allergy: Allergy linked to latex components
• Pollen Food Allergy Syndrome: Cross reactive symptoms between pollen allergens and certain plant based foods
• Risk Pattern in Severe Allergy: Helps doctors assess sensitisation patterns in people with severe or repeated allergic reactions

References

1. Ansotegui IJ, Melioli G, Canonica GW, Caraballo L, Villa E, Ebisawa M, et al. IgE allergy diagnostics and other relevant tests in allergy, a World Allergy Organization position paper. World Allergy Organ J. 2020;13(2):100080. PMID:32128023.
2. Luengo O, Cardona V. Component resolved diagnosis: when should it be used? Clin Transl Allergy. 2014;4:28. PMID:25250172.
3. Sastre J. Molecular diagnosis in allergy. Clin Exp Allergy. 2010;40(10):1442-1460. PMID:20682003.
4. Calamelli E, Liotti L, Beghetti I, Piccinno V, Serra L, Bottau P. Component-resolved diagnosis in food allergies. Medicina (Kaunas). 2019;55(8):498. PMID:31426616.
5. Platteel ACM, van der Pol P, Murk JL, Verbrugge-Bakker I, Hack-Steemers M, Roovers THWM, et al. A comprehensive comparison between ISAC and ALEX2 multiplex test systems. Clin Chem Lab Med. 2022;60(7):1046-1052. PMID:35470638.