Asthma Testing & Diagnosis – What You Should Know

Educational resource by Marylebone Diagnostic Centre (MDC)

Understanding Asthma & Why Diagnosis Matters

Asthma is a respiratory condition characterised by airway inflammation, bronchial hyperreactivity, and variable airflow obstruction. Common symptoms include:

• Wheezing
• Cough (especially at night or early morning)
• Chest tightness
• Shortness of breath

Because these symptoms overlap with other respiratory or cardiac conditions, accurate testing is essential. Early and correct diagnosis helps ensure the right treatments are selected by your physician, avoids unnecessary medications, and improves long-term control.

How Asthma is Typically Diagnosed

Since MDC is purely a diagnostic centre, we focus on the tests and investigations that help confirm or rule out asthma. The actual decision on treatment and follow-up lies with your GP or specialist. Here’s how the diagnostic pathway generally works:

1. Clinical History & Symptom Pattern

Physicians will ask detailed questions such as:

• When did symptoms start?
• Are symptoms intermittent or persistent?
• Do they worsen at night, early morning, or with triggers (cold air, allergens, exercise)?
• Any personal or family history of asthma, allergies, eczema?
• Smoking, occupational exposures, other lung disease risk factors

This history helps tailor which diagnostic tests are most appropriate.

2. Lung Function & Spirometry Testing

These tests gauge how well your lungs are working:

• Spirometry: measures volumes like FEV₁, FVC, and the FEV₁/FVC ratio.
• Bronchodilator reversibility test: after administering a bronchodilator (e.g., salbutamol), repeat spirometry to see if lung function improves (a key indicator supporting asthma).
• Peak flow measurements: tracking daily peak expiratory flow over time helps identify variability.
• Provocation / challenge testing (if required): using agents like methacholine to see how reactive the airways are under controlled stimulus.

3. Biomarkers & Laboratory Tests

While no single blood test can confirm asthma, certain biomarkers help support the diagnosis and subtype the disease. At MDC, we can perform or coordinate:

• Full Blood Count (FBC) including eosinophil count — elevated eosinophils may indicate eosinophilic (allergic) asthma
• Total and specific IgE / allergy panels — to detect sensitisation to allergens
• C-Reactive Protein (CRP) / other inflammation markers — to exclude concurrent inflammatory or infectious causes

We can provide fast turnaround labs so your GP or respiratory physician has data to guide management.

4. Imaging & Exclusion of Other Lung Disease

Because asthma mimics or coexists with other lung conditions, imaging may be needed:

• Chest X-ray: to rule out structural lung disease, pneumonia, or alternate causes
• High-Resolution CT (HRCT): in selected or atypical cases
• Other specialist imaging or tests (if referral by GP)

MDC can coordinate imaging and provide high-quality scans and reports to clinicians, but we do not prescribe or follow up treatments.

How MDC Supports the Diagnostic Journey

Although we do not provide asthma treatment or clinical appointments, MDC’s diagnostic role is pivotal. Here’s how we help:

1. High-quality lab and biomarker testing (full blood counts, IgE, inflammatory markers)
2. Imaging services (CXR, CT) with specialist radiology reports
3. Rapid result turnaround — efficient reporting to your GP or specialist
4. Data package for clinicians — we can bundle results (spirometry, labs, imaging) into a consolidated report
5. Patient education resources — information on how the tests work, preparing for tests, what to expect

Our goal is to empower you and your doctor with accurate diagnostic data — you remain under the care of your treating physician for therapy, monitoring, and follow-up.

What You Can Do: Preparing & Attributing Next Steps

Preparing for Diagnostic Tests

• Avoid bronchodilator inhalers (e.g. short-acting relievers) for a period before spirometry, if medically safe (ask your physician).
• Refrain from heavy meals, caffeine, or smoking for a few hours before tests.
• Wear loose clothing for comfort.
• Bring any previous test reports (spirometry, chest imaging, allergy tests) to your appointment.

After the Tests

• Your results will be sent to your GP or respiratory specialist.
• They will interpret the findings in conjunction with your symptoms and medical history.
• If asthma is confirmed, your clinician will prescribe inhalers, monitoring, and follow-up plans.
• If results are inconclusive or suggest another respiratory disorder, further specialist referral may follow.

FAQs

Read More

• NHS – Asthma
• British Lung Foundation – Asthma Tests
• American Lung Association – Asthma Diagnosis
• GOLD – Global Initiative for Asthma