Types of Allergy Blood Tests | IgE Antibody, ELISA, RAST Explained

How to Diagnose Allergies with Blood Test? Types of Allergy Blood Tests

What is an Allergy?

Allergies can disrupt your life with itchy eyes, runny noses, and even wheezing. But before you reach for that antihistamine, identifying the trigger is key! Blood allergy testing in India offers a convenient and reliable way to uncover the culprits hiding in your environment.

    • Immune reaction to harmless environmental substances
    • Caused by immune system mistaking it for harmful

      What are the Allergic Reaction Cascade?

      The allergic reaction cascade is the sequence of events that occurs when an allergen triggers an immune response in an allergic individual. It involves the following key steps:

      1. Exposure - An allergen enters the body, usually through the skin, respiratory system, or digestive system. Common allergens include pollen, pet dander, foods, medications, insect venom, and latex.
      2. IgE Antibody Activation - The allergen is detected by antigen presenting cells, which alert mast cells and basophils. These cells are coated in allergen-specific IgE antibodies, which become activated and bind to the allergen.
      3. Cell Activation & Degranulation - The cross-linking of IgE antibodies triggers the mast cells and basophils to rapidly degranulate, releasing inflammatory mediators like histamine, leukotrienes, and prostaglandins.
      4. Inflammatory Response - These inflammatory mediators act systemically, causing effects like vasodilation, mucus production, muscle contraction, and nerve fibre stimulation. This produces allergy symptoms like hives, runny nose, wheezing, etc.
      5. Late Phase Reaction - In some cases, a late phase reaction occurs where other immune cells are recruited over the next few hours, worsening symptoms. This can increase the risk of anaphylaxis.

      The allergic reaction cascade describes the sequence of immunological and inflammatory events triggered when an allergen causes IgE antibody cross-linking and cellular degranulation. The end result is the symptoms we associate with allergic reactions. Controlling allergies involves avoiding triggers and interrupting steps in this cascade.

      • Allergen exposure
      • IgE antibody release
      • Histamine and chemical release
      • Symptoms manifest

      How to Diagnose Allergies with Blood Test?

      There are several types of blood tests that can be used to help diagnose allergies and monitor allergy treatment. Some of the main allergy blood reports include:

        1. Allergen-specific IgE blood test: This detects and measures the amount of immunoglobulin E (IgE) antibodies to specific allergens, such as pollen, pet dander, foods, mould, insect venom, and medications. Levels indicate allergy sensitivity.
        2. Complete blood count with eosinophils (CBC): This checks white blood cell counts, including eosinophils. Elevated eosinophils can indicate an allergic response or parasitic infection that causes allergies.
        3. Total IgE blood test: This detects levels of both allergen-specific and non-specific IgE. Very high total IgE levels usually mean an allergy, infection, or condition causing immune system over-activity.
        4. Allergen immunotherapy blood tests: Periodic blood tests monitor immunotherapy effectiveness during treatment by checking IgE levels to determine if sensitivity is decreasing.
        5. Tryptase serum test: This analyses levels of tryptase enzyme in the blood after suspected anaphylaxis to confirm the reaction was allergy-related.
        6. Component-Resolved Diagnostics (CRD): This advanced test identifies specific components within an allergen, helping personalize treatment and avoid unnecessary restrictions.

      The blood tests like IgE, CBC, total IgE, immunotherapy tests, and tryptase provide information to help diagnose, monitor, and manage different types of allergies.

      #allergytests #elisa #rast

      What is IgE Antibody Test for Allergy?

      •  Measures allergen specific immunoglobulin levels
      •  Indicates immune sensitivity

      The immunoglobulin E (IgE) antibody blood test is one of the main allergy tests used to detect what substances a patient is allergic to. Here are some key details about the IgE antibody test:

      • What it measures: An IgE antibody test measures the level of allergen-specific IgE antibodies in the blood. IgE is an immunoglobulin involved in allergic reactions. The body produces IgE when it overreacts to allergens.
      • How it works: The test detects IgE antibodies to different allergen extracts introduced in the lab. Higher levels of IgE antibodies to an allergen indicate an allergy. Values above a specific quantitative cut-off indicate sensitivity.
      • Allergens tested: Common allergens tested include pollen, pet dander, moulds, foods, insect venom, medications, and latex. Panels test for IgE reactivity to groups of related allergens.
      • Test types: ELISA/EIA assays and immunoassays are commonly used. Newer testing methods like immunoCAP and microarray assays allow for more sensitivity and broader panels.
      • Interpreting results: Results indicate the likelihood, severity, and specific substances a patient is allergic to. Levels may also be tracked over time to monitor allergy control with treatment.

      Overall, allergen-specific IgE antibody blood tests are important for identifying causative allergens. This guides appropriate treatment approaches, such as avoidance measures, medications, and immunotherapy.

      What is ELISA Test for Allergy?

      ELISA is a widely used laboratory method for detecting allergen-specific IgE to help diagnose IgE-mediated allergic conditions.

      • Enzyme-linked immunoassay binding reaction
      • Identifies antigens triggering allergies

      The enzyme-linked immunosorbent assay (ELISA) is a common lab test used to detect and quantify allergen-specific immunoglobulin E (IgE) antibodies to help diagnose allergies. Here are some key details about using ELISA for allergy testing:

      • How it Works: The ELISA test uses allergen extracts bound to an enzyme-coated plate. The patient's serum is added, allowing any allergen-specific IgE antibodies present to bind to the allergens. After washing, enzyme-linked antibodies are added that will bind to any IgE. The enzyme converts a substrate to a measurable product, with more product indicating higher IgE levels.
      • Allergens Tested: ELISA can test IgE sensitivity to single or mixes of allergen extracts including pollen, moulds, foods, dust mite, pet dander, insect venom, and drugs. Panels group related allergens.
      • Benefits: ELISA offers affordable, quantitative testing for allergen-specific IgE. It is more sensitive and specific than skin prick testing. Many allergens can be tested from one serum sample. Good for young children.
      • Drawbacks: Results can be variable between labs. Lower sensitivity in detecting very low or very high IgE levels versus other tests. Unable to identify new/changing allergens over time as molecular biology does.
      • Results Interpretation: Quantitative IgE antibody levels indicate the likelihood, severity, and specific substances causing an allergic reaction. Levels are compared to reference cut-offs to determine allergy. Trends over time are also analysed.

      What is RAST Testing for Allergy?

      RAST pioneered allergy blood testing, but far more advanced allergen-specific IgE antibody assays using ELISA and other immunochemistry methods have supplanted RAST testing in modern clinical immunology labs.

      • Radioallergosorbent blood assay
      • Detects IgE antibodies to different allergens

      RAST (radioallergosorbent test) is an older blood test method used to detect allergen-specific immunoglobulin E (IgE) to diagnose allergy. Here are some key details:

      • How it Works: RAST uses radioisotope labels to detect IgE antibodies binding to allergen extracts immobilized on a solid phase substrate. The amount of radioactivity measured correlates with the amount of IgE present.
      • Allergens Tested: Like ELISA testing, RAST can test IgE sensitivity to pollens, foods, chemicals, mold, pet dander, dust mites, and insect venom using single or mixes of allergen extracts.
      • Benefits: As an in-vitro assay, RAST avoids skin test risks like anaphylaxis. It offers quantitative IgE antibody levels for many allergens from one blood sample.
      • Drawbacks: Less sensitive than modern immunoassays. Radioisotopes have safety/disposal issues. Unable to reliably detect very low or very high IgE. Does not assess cellular allergy mechanisms.
      • Current Use: Since better-performing immunoassays like chemiluminescent and fluorometric ELISA emerged, RAST technique is rarely performed today, replaced by these non-radiolabeled IgE tests.

      How Accurate are Blood Allergy Tests?

      There are several key benefits that make blood testing a useful diagnostic tool for allergies:

        1. Accurate diagnosis: Say goodbye to guesswork and identify your triggers with precision.
        2. Targeted treatment: Get personalized therapy plans based on your specific allergies.
        3. Improved quality of life: Manage your symptoms effectively and enjoy life to the fullest.
        4. Safety - Blood tests pose no risk of inducing anaphylaxis or causing dangerous reactions, unlike skin allergy testing. This allows testing where skin testing may be too risky.
        5. Accuracy - Quantitative blood tests analyze actual antibody concentrations, giving objective precision regarding the likelihood and severity of allergies. Results have improved accuracy over skin prick tests.
        6. Convenience - Only requires a simple blood sample collection. Multiple allergens can be tested simultaneously from one sample. Easier for hard-to-test patients.
        7. Age-Independent Testing - Allergy blood tests can be performed on patients of any age, including very young children that are poor candidates for skin testing.
        8. Identifies Precise Allergens - Blood assays allow the detection of IgE antibodies specific even to protein components of allergen extracts. This helps identify the precise allergenic proteins.
        9. Supports Additional Testing - A collected serum sample can undergo further immunological testing relevant to the allergy beyond just IgE testing.

          The allergy blood testing provides indispensable clinical immunology data safely, precisely, and conveniently to diagnose the specific causative allergens behind a patient's symptoms.

          What is the Cost of Blood Allergy Testing in India?

          The cost varies depending on the type of test and the number of allergens tested. Expect to pay anywhere between ₹650 to ₹6,000 per test.

          Where to Get Tested for allergies in India?

          healthcare nt sickcare is your trusted partner for reliable and affordable blood allergy testing in India. Our NABL-accredited laboratory and experienced team ensure accurate results and personalized care.


          At healthcare nt sickcare, our allergy profiles leverage multiple blood investigation methods like IgE antibody tests, ELISA and RAST to uncover your sensitivity. Our allergists create personalized treatments thereafter so you can breathe easy! Book your test today.

          Don't let allergies dictate your life! Take control with blood allergy testing in India. At healthcare nt sickcare, we empower you with accurate diagnosis and personalized care to lead a healthier, happier life. Book your test online or visit our Pune laboratory today!

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