🩸 Understanding Blood Tests for Aspergillosis: A Patient Guide

If you’ve been told you have ABPA, CPA, or another form of aspergillosis, your doctors may run several blood tests. These tests help confirm the diagnosis, guide treatment, and monitor your progress.

Please remember that blood tests only form part of the process of diagnosing and managing aspergillosis – scans, case history, symptoms and more are also essential parts of a doctor’s reasoning. To get a complete picture of your diagnosis, we need all of the parts.

Here’s a breakdown of what each test is, why it’s done, and what it means:

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1. Total IgE (Immunoglobulin E)

🧪 What it is: A measure of all the allergy-related antibodies in your blood.
📌 Why it’s used:

• In ABPA, total IgE is usually very high — often above 1,000 IU/mL.

• Doctors use it to help diagnose ABPA and then to monitor flare-ups or improvements.

💡 What it tells you:

• High IgE suggests an allergic response, often to Aspergillus.

• A fall in IgE after treatment often shows you’re getting better.

• A sudden rise might mean a flare-up.

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2. Aspergillus-specific IgE

🧪 What it is: A test that looks for allergy antibodies targeting Aspergillus fumigatus.
📌 Why it’s used:

• Helps confirm whether your immune system is reacting to Aspergillus.

• It’s part of the diagnosis for ABPA and SAFS (Severe Asthma with Fungal Sensitisation).

💡 What it tells you:

• A positive result means you are sensitised (allergic) to Aspergillus.

• It doesn’t prove infection — just allergy.

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3. Aspergillus-specific IgG

🧪 What it is: A test for long-term antibody response to Aspergillus.
📌 Why it’s used:

• Important in diagnosing Chronic Pulmonary Aspergillosis (CPA).

• Also used in Aspergillus bronchitis.

💡 What it tells you:

• High IgG means your immune system has been exposed to Aspergillus over time, likely indicating long-term infection.

• It’s not an allergy test — it looks for signs of chronic infection or colonisation.

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4. Aspergillus precipitins (Immunodiffusion or counter-immunoelectrophoresis)

🧪 What it is: An older test to detect antibodies to Aspergillus proteins.
📌 Why it’s used:

• Sometimes used in CPA or fungal ball (aspergilloma) diagnosis.

• Less sensitive than IgG ELISA but still used in some labs.

💡 What it tells you:

• A positive test supports the diagnosis of chronic infection.

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5. Eosinophil Count

🧪 What it is: A blood count of a type of white cell linked to allergy and inflammation.
📌 Why it’s used:

• In ABPA, eosinophils are often elevated, especially during flares.

• It helps show how much inflammation is present.

💡 What it tells you:

• High eosinophils support a diagnosis of allergic inflammation.

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6. Galactomannan (in blood or BAL fluid)

🧪 What it is: A test for fungal cell wall fragments released by Aspergillus, useful when detecting the patient’s immune response to infection is limited.
📌 Why it’s used:

• Mainly used in hospitals to detect invasive aspergillosis, especially in people with weakened immune systems.

💡 What it tells you:

• A positive result may suggest active infection — but false positives can occur.

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7. Beta-D-Glucan (BDG)

🧪 What it is: A general marker of fungal infection in the bloodstream.
📌 Why it’s used:

• Used to detect invasive fungal infections, especially in ICU patients.

💡 What it tells you:

• Not specific to Aspergillus, but may support the diagnosis of serious fungal disease.

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🧭 Putting It All Together

Different types of aspergillosis need different combinations of tests:

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🗨️ Questions to Ask Your Doctor

• What type of aspergillosis do I have?

• Which tests are being used to monitor my condition?

• Should I expect these results to go up and down?

• What symptoms should I report if things change?