For patients in the UK and internationally
If you are living with aspergillosis, including forms such as chronic pulmonary aspergillosis (CPA), allergic bronchopulmonary aspergillosis (ABPA), or severe asthma with fungal sensitisation (SAFS), you may have had blood tests that measure how your immune system responds to Aspergillus, a common type of fungus.
This guide explains the role of these tests, why results may vary between hospitals, and what they mean for diagnosis and ongoing care.
🔬 What Are These Blood Tests?
✅ Total IgE
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Measures your body’s overall allergic response.
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Often raised in people with ABPA or SAFS, but also in asthma, eczema, and parasitic infections.
✅ Aspergillus-Specific IgE
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Detects allergic reaction specifically to Aspergillus fumigatus.
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Helps diagnose ABPA and SAFS.
✅ Aspergillus-Specific IgG
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Measures immune response to longer-term exposure to Aspergillus.
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Mainly used to help diagnose CPA, but can also support ABPA diagnosis.
📊 What Are the Normal Ranges?
📌 Total IgE Reference Ranges (UK Examples)
| Age Group | NHS Reference Range |
|---|---|
| Children | Varies by age, up to ~75 kU/L |
| Adults | 0–75 to 5–120 kU/L (depends on hospital) |
In ABPA, total IgE is usually > 500 kU/L, and sometimes exceeds 1000 kU/L.
📌 Aspergillus-Specific IgE: Positive Ranges
| Level (kUA/L) | What It Means |
|---|---|
| <0.35 | Negative |
| 0.35–0.7 | Borderline |
| 0.7–3.5 | Positive |
| >3.5 | Strongly positive |
| >17.5 | Very strongly positive |
📌 Aspergillus-Specific IgG: Positive Ranges
| Test Used | Positive Threshold |
|---|---|
| ImmunoCAP (most NHS labs) | >27–40 mgA/L |
| Bordier ELISA | >50–75 AU/mL |
| LDBio ICT (lateral flow strip) | Visual positive line |
The exact “positive” level depends on the test platform used by the lab. Always check which test was used when reviewing results.
🧪 Why Do Reference Ranges Differ Between Hospitals?
It’s common for different hospitals and countries to use slightly different tests and reference ranges. This is due to:
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Different brands or types of test kits (e.g. ImmunoCAP, Bordier, Serion, LDBio)
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Varying units of measurement
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Locally validated ranges based on the population
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Differences in clinical protocols or disease thresholds
For example, a test result of Aspergillus IgG at 38 mgA/L may be seen as positive in one hospital and borderline in another depending on which assay is used.
🧭 How These Tests Fit into Aspergillosis Diagnosis
🩺 Blood Tests Help Guide the Diagnosis, But Are Not Enough Alone
| Condition | Typical Test Findings |
|---|---|
| ABPA | Total IgE >500 kU/L + Aspergillus-specific IgE >0.35 kUA/L + often raised IgG |
| SAFS | Raised Aspergillus-specific IgE + asthma + poor steroid response |
| CPA | Aspergillus-specific IgG essential; total IgE and IgE may be normal |
Diagnosis always depends on a combination of factors — not just a blood test.
🧩 Other Essential Parts of Diagnosis
| Diagnostic Tool | What It Does |
|---|---|
| Chest CT scan | Detects cavities, nodules, or bronchiectasis |
| Sputum culture or PCR | Confirms presence of Aspergillus |
| Galactomannan or beta-D-glucan | Sometimes used to monitor invasive disease |
| Lung function tests | Assess asthma or airflow limitation |
| Symptoms | Breathlessness, cough, weight loss, fatigue |
| Treatment response | Helps confirm diagnosis if patient improves with treatment |
Blood tests are just one piece of the puzzle. Doctors always interpret them alongside imaging, symptoms, and history.
🩺 What About Management?
Once diagnosed, managing aspergillosis involves more than just monitoring blood tests. Your care plan may include:
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Antifungal medication (e.g. itraconazole, voriconazole)
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Steroids or biologics (especially in ABPA)
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Physiotherapy to clear mucus
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Regular imaging (e.g. CT scans)
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Monitoring IgE/IgG over time
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Patient support for fatigue, emotional health, and quality of life
📋 Understanding Your Results: What Do They Mean?
When you receive blood test results like total IgE, Aspergillus-specific IgE, or Aspergillus-specific IgG, you may see a number alongside a reference range (sometimes called the “normal range”). This helps show whether your result is considered low, normal, or high in that specific laboratory.
🧾 Example:
| Test | Your Result | Lab Reference Range | Interpretation |
|---|---|---|---|
| Total IgE | 580 kU/L | 0–120 kU/L | Elevated |
| Aspergillus-specific IgE | 0.9 kUA/L | >0.35 = positive | Positive |
| Aspergillus-specific IgG | 39 mgA/L | 0–27 mgA/L | Borderline high |
❓ Is a Slightly High Result a Problem?
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A mild or borderline elevation does not automatically mean disease.
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Some people may have a raised IgE or IgG but no active symptoms or signs of aspergillosis.
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Other people with clear disease may have only modest rises in their test levels.
🔍 Important: Test results must always be interpreted in the context of your overall health, scan results, and symptoms.
✅ Let Your Doctor Guide You
It’s completely normal to feel uncertain or anxious about test results — especially if a number is just above the “normal range.” But:
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Let your doctor or specialist interpret the result as part of your whole clinical picture.
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They may repeat the test, combine it with a CT scan or lung function test, or monitor changes over time.
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Some test levels, like total IgE in ABPA, are tracked over months to see if treatment is working.
💬 Ask your doctor:
“How does this result fit in with my symptoms and scan findings?”
🧠 Final Takeaway
Blood tests like IgE and IgG are essential tools in diagnosing and managing aspergillosis, but they are only one part of the bigger picture. Imaging, symptoms, response to treatment, and even how you feel day-to-day are just as important.
Always ask for a copy of your results with reference ranges, and bring them to appointments.
And remember — a slightly raised result doesn’t always mean something is wrong. Your doctor is the best person to interpret it for you.
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