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Immune System

Blood Testing for Asthma

Blood testing supports asthma care by tracking airway inflammation and systemic stress. At Superpower, we offer Eosinophils and CRP tests for asthma assessment. Superpower provides both in-clinic and at-home blood testing. Home blood testing for asthma is available in selected states. See FAQs below for more information.

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What are Asthma biomarkers

Asthma biomarkers are measurable signals in your blood that mirror the inflammation inside your airways. Blood testing highlights the immune pathways that tighten and swell the bronchial tubes, helping distinguish asthma driven by allergy-type inflammation from other patterns. Key players include eosinophils (a type of white blood cell) and allergic antibodies (IgE), which rise when type 2 immune responses are active (T2 inflammation). These arise from immune cells and the airway lining and reflect the release of inflammatory messengers (cytokines such as IL‑5 and IL‑13) that promote mucus production, airway sensitivity, and flare‑ups. Additional blood proteins from the airway-epithelial response (periostin) can also signal this biology. By capturing this internal story, biomarkers make invisible airway inflammation visible—showing how “hot” the disease is, how likely symptoms or exacerbations are, and which biologic targets may be relevant. In short, asthma biomarkers translate complex airway immune activity into objective clues your clinician can use to characterize the disease and personalize care.

Why is blood testing for Asthma important?

  • Confirm your asthma’s inflammation type to personalize inhaler and biologic choices.
  • Spot eosinophilic asthma that responds well to inhaled steroids and biologics.
  • Flag higher flare risk when eosinophils run elevated despite current therapy.
  • Clarify symptoms by flagging infection-related inflammation when CRP is elevated.
  • Guide biologic eligibility using eosinophil thresholds like 150–300 cells per microliter.
  • Track trends to confirm control, steroid response, and relapse risk between visits.
  • Explain non-asthma causes of high eosinophils, like allergies or parasites.
  • Best interpreted with symptoms, FeNO, spirometry, and recent exacerbation history.

What insights will I get?

Asthma blood testing provides insight into how your immune system is functioning and how it may be influencing your overall health. Asthma is not just a lung condition—it’s a reflection of how your body manages inflammation and immune responses, which can affect energy, metabolism, cardiovascular health, and even cognitive function. At Superpower, we focus on two key biomarkers for asthma: Eosinophils and C-reactive protein (CRP).

Eosinophils are a type of white blood cell involved in allergic reactions and defense against certain infections. In asthma, eosinophils can become elevated, signaling that the immune system is reacting strongly—sometimes too strongly—to environmental triggers. CRP is a protein produced by the liver in response to inflammation anywhere in the body. While CRP is not specific to asthma, higher levels can indicate ongoing inflammation, which is often present during asthma flare-ups or poorly controlled disease.

Healthy levels of eosinophils suggest that the immune system is balanced and not overreacting, which supports stable airway function and reduces the risk of asthma symptoms. Similarly, a low CRP level indicates minimal systemic inflammation, which is associated with better respiratory health and overall stability. Together, these markers help reveal whether the body’s inflammatory and immune responses are under control, which is essential for maintaining healthy lung function in asthma.

Interpretation of these biomarkers can be influenced by factors such as recent infections, allergies, age, pregnancy, and certain medications like steroids. Laboratory methods and reference ranges may also vary, so results are best understood in the context of your overall health and medical history.

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Frequently Asked Questions About

What is Asthma blood testing?

Asthma blood testing looks for signals of airway and systemic inflammation in your blood. Superpower measures eosinophils (a white blood cell linked to allergic/type 2 airway inflammation) and C‑reactive protein, or CRP (a marker of whole‑body inflammation). These markers don’t diagnose asthma by themselves; they help characterize your asthma phenotype, gauge inflammation burden, and track response to therapy alongside symptoms and lung function.

Why should I get Asthma blood testing?

It clarifies what kind of inflammation is driving your asthma. Higher blood eosinophils point to eosinophilic/type 2 asthma and greater flare risk; CRP shows if there is broader systemic inflammation that may worsen control. With Superpower, eosinophils and CRP help you and your clinician link biology to symptoms, predict exacerbation risk, and monitor whether treatment is reducing inflammation.

Can I get a blood test at home?

Yes. With Superpower, our team member can organise a blood draw in your home.

How often should I test?

Start with a baseline. Recheck when symptoms change, after major treatment changes, or around exacerbations to see how inflammation shifts. If you have eosinophilic features or frequent flares, periodic monitoring (for example, once or twice a year) can help track stability. Routine testing is otherwise occasional and guided by your clinical picture.

What can affect biomarker levels?

Corticosteroids and biologics that target type 2 pathways lower eosinophils. Allergen exposure, parasitic infection, and active asthma flares raise eosinophils. CRP rises with infection, obesity, smoking, autoimmune disease, and recent injury or surgery. Intense exercise, acute stress, and time of day cause modest shifts. A single abnormal value may reflect an intercurrent illness rather than asthma activity.

Are there any preparations needed before the blood test for Eosinophils, CRP?

No fasting is required. Avoid unusually strenuous exercise right before the draw, as it can transiently shift white cell counts and CRP. If you’re on steroids or biologics, the timing of your dose can influence eosinophils; note dose timing when testing. Testing during a flare versus when well will show different biology, so context matters.

Can lifestyle changes affect my biomarker levels?

Yes. Factors that reduce whole‑body inflammation tend to lower CRP, and factors that reduce allergic/type 2 airway activation tend to lower eosinophils. Body weight, smoking exposure, sleep quality, infection burden, and allergen exposure all influence these pathways. The biomarkers reflect the inflammatory state across systems; when that state shifts, the numbers follow.

How do I interpret my results?

Blood eosinophils are typically below about 500 cells/µL. Levels above ~150 suggest type 2 inflammation; above ~300 often signal higher exacerbation risk and potential responsiveness to anti‑eosinophilic therapies. CRP is usually low (<3 mg/L) when systemic inflammation is minimal; marked elevations often reflect infection or another inflammatory trigger. These tests support, but do not replace, symptom history and lung function in diagnosing and managing asthma.

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