Aspergillus fumigatus IgE

Measures IgE antibodies to Aspergillus fumigatus, a common mold, to show whether your immune system has become sensitized to it.

AI-verified against cited sources. Awaiting expert reviewAlso called m3, M003, A. fumigatus sIgELOINC 6025-1

Check your result

Your A. fumigatus IgE result

Sex (optional)

Age (optional)

Type your result to see where it falls.

Nothing you type here leaves your browser.

What it is

This test measures IgE, the antibody type involved in allergic reactions, against Aspergillus fumigatus (ImmunoCAP m3). It is a common mold found in soil, compost, decaying plants and damp buildings, and everyone breathes in its tiny spores. Results come in kilounits per liter (kU/L), and many labs also print a class from 0 to 6. The class shows how much antibody was found, not how severe any illness is.

Why it matters

Most people who have IgE to this mold never have a problem from it. In some people with asthma or cystic fibrosis, mold sensitization is linked to asthma that is harder to control and, in a small group, to a lung condition called allergic bronchopulmonary aspergillosis (ABPA). Clinicians read this result together with your symptoms, total IgE, blood eosinophils and sometimes chest imaging.

If it’s high

A level above the 'none detected' range means the lab found IgE antibodies to this mold. This is called sensitization. It is not the same as an allergy or a lung condition, and many sensitized people have no symptoms. Higher numbers mean more antibody, not necessarily more severe illness. Your clinician can put the result in context.

Common causes

Sensitization with no symptoms
Allergic asthma or hay fever, with mold as one of several triggers
IgE that cross-reacts from related molds such as Penicillium, Alternaria or Cladosporium
Allergic bronchopulmonary aspergillosis (ABPA), mostly in people with asthma or cystic fibrosis (uncommon)

What can help

Talk with a clinician or an allergist about whether this result fits your symptoms
Ask whether other tests would add context, such as total IgE, an eosinophil count, Aspergillus IgG or chest imaging
Ask about ways to reduce mold at home, such as fixing leaks and drying damp areas

Usual ranges

What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.

For adults: 0–0.09 kU/L. Source: ARUP Laboratories, Labcorp, Children's Minnesota Laboratory, Thermo Fisher Scientific (Phadia), American Academy of Pediatrics (Pediatrics).

Adults (this one applies)0–0.09 kU/L
Sources: ARUP Laboratories, Labcorp, Children's Minnesota Laboratory, Thermo Fisher Scientific (Phadia), American Academy of Pediatrics (Pediatrics)

ImmunoCAP IgE classes (ARUP, Iowa, Children's Minnesota and CUHK; labs differ on which class an exact edge value falls in)

Class 0: no significant level detectedbelow 0.1 kU/L
Class 0/1: clinical relevance undetermined0.1 to under 0.35 kU/L
Class 1: low0.35 to under 0.7 kU/L
Class 2: moderate0.7 to under 3.5 kU/L
Class 3: high3.5 to under 17.5 kU/L
Class 4: very high17.5 to under 50 kU/L
Class 5: very high50 to under 100 kU/L
Class 6: very high100 and above kU/L

Labcorp class scale (cutoffs differ from the ImmunoCAP scale above; exactly 100.00 is class V)

Class 0: negativebelow 0.1 kU/L
Class 0/I: equivocal or low0.1 to under 0.32 kU/L
Class I: low0.32 to under 0.56 kU/L
Class II: moderate0.56 to under 1.41 kU/L
Class III: high1.41 to under 3.91 kU/L
Class IV: very high3.91 to under 19.01 kU/L
Class V: very high19.01 to under 100 kU/L
Class VI: very high100 and above kU/L

What can affect your result

Having asthma, cystic fibrosis or other allergic conditions, which make mold sensitization more common
How much mold you are exposed to at home, at work and outdoors
Cross-reacting IgE from related molds
The lab and test brand, because results from different systems are not directly comparable
Antihistamines generally don't interfere with blood IgE tests, unlike skin tests (AAP). MedlinePlus advises telling your provider about everything you take, since some medicines may matter for this test, so ask your clinician before changing any medicine.
Assays from different manufacturers aren't equivalent, so compare results only from the same lab and method (AAP).

Slow. IgE levels usually shift over months to years, not weeks.

When to talk to a clinician

Get urgent medical help for severe trouble breathing or wheezing that does not ease. Talk with a clinician soon if you have asthma that is getting harder to control, a cough that will not go away, or you cough up thick mucus plugs, even if this result is in the usual range.

Questions you could ask

Which lab method was used, and should I use the same lab for future results?
Does this result fit my symptoms?
Would checking total IgE, an eosinophil count or Aspergillus IgG add useful information?
Should I see an allergist or a lung specialist about this?
My result is in the usual range but I still have symptoms. What should we look at next?

Questions people ask

Does a positive Aspergillus IgE mean I have ABPA?

No. Sensitization to this mold is much more common than ABPA, which Thermo Fisher puts at about 1 to 2.5% of people with asthma. Clinicians look at several things together, such as total IgE, blood eosinophils, Aspergillus IgG and chest imaging, along with your symptoms.

What do the class numbers 0 to 6 mean?

The class groups the kU/L number from none detected (class 0) to very high (class 6). Higher classes mean more antibody and a higher chance of a reaction, but not a more severe one. Labcorp's class cutoffs differ from the ones ARUP and many hospital labs use, so compare the kU/L number rather than the class between labs.

Can I compare my result with one from another lab?

Not directly. Different labs and test makers use assays that are not equivalent, so track your trend with the same lab and method when you can.

Show the science and sources

For clinicians and researchers

Quantitative IgE to an Aspergillus fumigatus extract (ImmunoCAP m3) by fluoroenzyme immunoassay; ARUP and Labcorp both use the ImmunoCAP system. The system reports about 0.1 to 100 kUA/L, and results from the different FDA-cleared IgE systems are not equivalent (AAP 2012). In the 2024 ISHAM ABPA guideline, A. fumigatus-specific IgE of at least 0.35 kUA/L plus total IgE of at least 500 IU/mL are the two required criteria, together with at least two of: A. fumigatus IgG, blood eosinophils of at least 500 per µL, or compatible imaging, in people with a predisposing condition such as asthma or cystic fibrosis. Thermo Fisher describes Asp f 1 (m218), Asp f 2 (m219) and Asp f 4 (m221) as markers of genuine A. fumigatus sensitization, ties Asp f 4 and Asp f 6 (m222) to ABPA diagnosis, and notes that Asp f 3 and Asp f 6 cross-react with other organisms. A positive extract with negative components can mean sensitization to an untested component. Cross-reactivity with Penicillium, Alternaria and Cladosporium is described. ARUP reports 0.10 to 0.34 kU/L as 'clinical relevance undetermined'.

LOINC 6025-1 (primary), 112148-2. Specimen: serum.

Sources

Allergen, Fungi and Molds, Aspergillus fumigatus (test 0055061), ARUP Laboratories
Allergic Bronchopulmonary Aspergillosis (ABPA) Panel (test 2004243), ARUP Laboratories
Aspergillus fumigatus Antibody, IgE (test 602471), Labcorp
Sample report 607120, Allergens with Component Reflexes Area 20 (class description table), Labcorp
Allergen (IgE) ImmunoCAP, University of Iowa Hospitals & Clinics, Pathology Handbook
Allergen IgE (laboratory test information), Children's Minnesota Laboratory
Immunoglobulin E (IgE, Allergen-Specific), Serum, Chinese University of Hong Kong, Prince of Wales Hospital ward manual
Your quick guide to using ImmunoCAP Specific IgE testing, Thermo Fisher Scientific (Phadia) (2024)
Allergy Testing in Childhood: Using Allergen-Specific IgE Tests (clinical report), American Academy of Pediatrics (Pediatrics) (2012)
Allergy Blood Tests, MedlinePlus (National Library of Medicine)
ImmunoCAP Specific IgE tests: Aspergillus fumigatus (testing algorithm), Thermo Fisher Scientific (Phadia) (2025)
Allergen Encyclopedia: Aspergillus fumigatus (m3), Thermo Fisher Scientific (Phadia)
Revised ISHAM-ABPA working group clinical practice guidelines for diagnosing, classifying and treating allergic bronchopulmonary aspergillosis/mycoses, European Respiratory Journal (2024)

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.