Alternaria Alternata (M6) IgE: What Your Mold Allergy Test Result Means
Other names: Alternaria Alternata (M6) IgE, M006 IgE Alternaria Alternata, M006-IgE Alternaria Alternata, Alternaria Alternata IgE, Alternaria Alternata Mold IgE, Alternaria Alternata M6, Alternaria M6 IgE, A. Alternata IgE, Alternaria Alternata Immunoglobulin E, Alternaria Alternata IgE High, Alternaria Alternata IgE Normal Range, Alternaria Alternata IgE Allergy, Alternaria Alternata (M6) IgE High, IgE M6, M006 IgE, Alternaria Tenuis IgE, A. Tenuis (M6) IgE, Alternaria Tenuis M6, Mold Allergy Test IgE, Allergen Alternaria Alternata IgE, Alternaria Alternata Allergen, Allergy to Alternaria Alternata, Alternaria IgE Antikoru (Turkish), Alergia Alternaria Alternata (Spanish), Alternaria Alternata Allergie (German/French)
Reference range:
QUICK ANSWER
Alternaria alternata (M6) IgE measures your immune system's IgE antibody response to Alternaria alternata — a common outdoor mold and one of the most clinically significant mold allergens associated with asthma.
A positive result means your immune system has produced IgE antibodies against Alternaria mold. The higher the level, the greater the degree of immune sensitization — though sensitization does not always cause symptoms.
Quick result lookup (patient-facing):
| Your result (kU/L) | What it usually means |
|---|---|
| Below 0.10 | Negative — no detectable sensitization |
| 0.10–0.34 | Borderline / equivocal — significance uncertain |
| 0.35–3.49 | Positive sensitization — mild to moderate |
| 3.50–17.49 | High sensitization |
| Above 17.5 | Very high sensitization |
Clinical interpretation at a glance:
| Level | Typical clinical meaning |
|---|---|
| Negative | Alternaria sensitization not detected — symptoms are less likely to be caused by Alternaria allergy |
| Low positive (0.35–0.69) | Mild sensitization — symptoms possible, especially during high-exposure periods |
| Moderate–high (0.70–17.49) | Sensitization more likely clinically relevant — discuss with clinician if symptoms are present |
| Very high (above 17.5) | Strong sensitization — interpret alongside symptoms and exposure history; discuss with allergist if asthma is present |
IgE allergy class interpretation (Quest Diagnostics / standard scale):
| Result (kU/L) | Class | Interpretation |
|---|---|---|
| Below 0.10 | 0 | No detectable IgE — no sensitization identified |
| 0.10–0.34 | 0/1 | Equivocal — clinical significance uncertain; may warrant repeat testing |
| 0.35–0.69 | 1 | Low positive — mild sensitization |
| 0.70–3.49 | 2 | Moderate sensitization |
| 3.50–17.49 | 3 | High sensitization |
| 17.50–49.99 | 4 | Very high sensitization |
| 50.00–99.99 | 5 | Very high sensitization |
| Above 100 | 6 | Extremely high sensitization |
Important: IgE levels do not directly predict symptom severity. A low positive result can cause significant symptoms in a sensitized patient during high-exposure periods; a high result may cause minimal symptoms in someone with low Alternaria exposure. Always interpret alongside symptoms and exposure history.
WHAT IS ALTERNARIA ALTERNATA (M6) IGE?
Alternaria alternata is one of the most clinically significant outdoor mold allergens studied in allergy medicine, and one of the mold allergens most strongly associated with asthma severity and asthma-related hospitalization. On the Quest Diagnostics allergy panel, it is identified by the code M006 (sometimes written M6 or M-6).
The M6 IgE test measures the level of immunoglobulin E (IgE) antibodies specific to Alternaria alternata proteins in your blood. IgE is the antibody class involved in Type I (immediate) allergic reactions — the mechanism behind hay fever, allergic asthma, hives, and anaphylaxis. When a sensitized person inhales Alternaria spores, IgE antibodies on mast cells in the airways trigger the release of histamine and other inflammatory mediators, causing allergy symptoms.
Alternaria alternata vs Alternaria tenuis: These names are sometimes used interchangeably — Alternaria tenuis is an older name for Alternaria alternata, and some lab reports and older literature use "tenuis." They refer to the same organism and the same allergen.
WHAT DOES A HIGH ALTERNARIA ALTERNATA IGE RESULT MEAN?
A high Alternaria alternata IgE result means the immune system has produced significant IgE antibodies against Alternaria mold proteins — indicating sensitization. The higher the class, the stronger the sensitization, and the more likely exposure to Alternaria spores is to trigger allergic symptoms.
Clinical significance of high Alternaria IgE:
Alternaria sensitization is particularly clinically significant compared to many other mold allergens because:
- It is strongly associated with asthma severity — Alternaria sensitization is one of the few mold allergies associated with life-threatening asthma exacerbations
- It is linked to severe asthma attacks triggered by high outdoor spore counts (particularly late summer and early autumn)
- Children with Alternaria sensitization have a significantly higher risk of developing persistent asthma
- A positive result in someone with asthma should be discussed with the treating physician
Common symptoms associated with Alternaria sensitization:
- Nasal congestion, runny nose, sneezing
- Itchy, watery eyes
- Coughing and wheezing
- Allergic rhinitis (hay fever)
- Asthma exacerbations — especially during peak spore season (late summer to early autumn)
- Allergic sinusitis
- In some patients: hives (urticaria) when consuming yeast- or mold-containing foods
When are symptoms typically worst?
Alternaria spore counts peak in late summer and early autumn in temperate climates (typically July–October in the Northern Hemisphere). Spores are highest in warm, dry, windy conditions — especially in the afternoon. In hot, dry climates (US Southwest, Mediterranean), spore season may extend longer.
WHAT DOES A LOW OR NEGATIVE ALTERNARIA IGE RESULT MEAN?
A result below 0.10 kU/L means no detectable Alternaria-specific IgE was found — indicating no current sensitization to this mold.
A result between 0.10 and 0.35 kU/L is considered equivocal by Quest Diagnostics — the significance of these low-level IgE values is uncertain. They may represent very early sensitization, non-specific binding, or background noise. Clinical context determines whether further evaluation is warranted.
A negative result does not rule out mold sensitivity entirely — other mold species (Cladosporium, Aspergillus, Penicillium, Helminthosporium) have separate IgE tests and may be relevant if Alternaria is negative but symptoms persist.
HOW COMMON IS ALTERNARIA ALLERGY?
Alternaria alternata is one of the most widespread mold allergens globally, but sensitization rates vary significantly by geography and population:
- Approximately 5% of the general population is estimated to be sensitized to Alternaria
- Among people with allergic asthma, sensitization rates are substantially higher — studies report 15–30% in temperate climates and up to 38% among inner-city children with asthma in the United States
- Sensitization is more common in warm, dry climates where outdoor Alternaria spore counts are highest — including the US Southwest, Mediterranean, and parts of Australia
- In children, reported sensitization rates vary dramatically by region — from less than 1% in Austria to 50% in Arizona
- Alternaria is the most common mold allergy among children with asthma in US inner-city populations
This geographic and population variability means a positive result is clinically more meaningful in high-exposure regions and in patients with asthma or known atopic conditions.
WHERE IS ALTERNARIA MOLD FOUND?
Alternaria alternata is primarily an outdoor mold found in soil and on decaying plant material. It is the most prevalent mold in dry, warm climates and a significant agricultural pathogen affecting grains, fruits, and vegetables.
Outdoor sources: Soil, dead vegetation, compost, leaf piles, crop residue, hay, straw, and decaying wood. Spore counts are highest in warm, dry, windy weather — particularly in the afternoon.
Indoor sources: Alternaria can enter indoors through windows, doors, and HVAC systems. Indoor growth occurs primarily in areas with moisture: bathrooms, basements, window frames, carpet, drywall, and HVAC components. Indoor concentrations correlate with outdoor levels.
Peak season: Late summer to early autumn in temperate climates. In dry, warm regions, elevated counts may persist longer.
MANAGING ALTERNARIA MOLD ALLERGY
Exposure reduction:
- Monitor outdoor mold counts (similar to pollen forecasts) and limit outdoor time when counts are high
- Wear a mask when gardening, raking leaves, or working with plant material
- Keep indoor humidity below 45% — use dehumidifiers in basements and bathrooms
- Use HEPA-rated air filters and change HVAC filters regularly
- Fix plumbing leaks and water intrusion promptly — moisture control is the most effective indoor mold prevention
- Use exhaust fans in bathrooms and kitchens
- Remove carpet from bathrooms and basements
Medical management:
Options typically discussed with an allergist or treating physician include antihistamines, nasal corticosteroids, decongestants, anti-inflammatory medications (such as montelukast), and allergen immunotherapy (allergy shots or sublingual immunotherapy), which may help build tolerance to Alternaria exposure over time.
FAQ about ALTERNARIA ALTERNATA (M6) IGE
-
Can Alternaria IgE levels go down over time?
Yes. IgE levels may decrease if exposure falls, if the immune response changes over time, or following allergen immunotherapy. However, a lower result does not necessarily mean symptoms will disappear, and a higher result does not always mean symptoms will worsen. Clinical symptoms remain more important than the number alone. If you are retesting after immunotherapy or a change in living environment, discuss the trend in your results with your allergist rather than interpreting any single value in isolation. -
Can I have mold allergy symptoms if my Alternaria IgE is negative?
Yes. A negative Alternaria IgE does not rule out all mold-related symptoms. Symptoms may be caused by sensitization to other molds (Cladosporium, Aspergillus, Penicillium, Helminthosporium all have separate IgE tests), non-allergic irritant responses to mold exposure, local allergic responses in the nasal mucosa not always reflected in blood IgE levels, or entirely unrelated environmental triggers. If symptoms persist despite a negative Alternaria IgE, a broader allergy panel or skin prick testing with an allergist may help identify other triggers. -
What does Alternaria alternata (M6) IgE mean on my lab report?
Alternaria alternata (M6) IgE measures the level of IgE antibodies your immune system has produced against Alternaria alternata mold. M006 (or M6) is the Quest Diagnostics allergen code for this mold. A result above 0.35 kU/L is considered a positive finding indicating sensitization. The higher the result, the greater the degree of sensitization — though symptom severity also depends on exposure level and individual immune response. -
What is a normal range for Alternaria alternata IgE?
A result below 0.10 kU/L is considered non-reactive — no detectable IgE sensitization. Results between 0.10 and 0.35 kU/L are equivocal (uncertain significance). Results of 0.35 kU/L and above indicate positive sensitization, classified in increasing severity from Class 1 (mild, 0.35–0.69 kU/L) through Class 6 (extremely high, above 100 kU/L). -
What does high Alternaria alternata IgE mean?
A high result means your immune system has produced significant IgE antibodies against Alternaria mold proteins. This indicates sensitization — your immune system recognizes Alternaria as a threat and is primed to react when you inhale its spores. Higher classes (3–6) are associated with more reactive immune responses and a greater risk of symptoms during high-spore-count periods. Alternaria sensitization is particularly important to discuss with a physician if you have asthma, as it is one of the mold allergens most strongly linked to severe asthma exacerbations. -
Is Alternaria alternata the same as Alternaria tenuis?
Yes — Alternaria tenuis is an older taxonomic name for Alternaria alternata. They refer to the same organism. Some lab reports, especially older ones, use "Alternaria tenuis" or "A. tenuis" while others use "Alternaria alternata" or "A. alternata." The allergen (M006) is the same in both cases. -
What is M006 IgE on a Quest Diagnostics report?
M006 is the Quest Diagnostics allergen code for Alternaria alternata (also called Alternaria tenuis). "M" indicates a mold allergen, and "006" is the specific allergen number. The full test name is Alternaria alternata (M6) IgE — measuring IgE antibodies specific to this mold species. -
Can a positive Alternaria IgE result cause asthma?
Alternaria sensitization does not cause asthma directly, but it is one of the strongest risk factors for asthma development and severity in both children and adults. Exposure to Alternaria spores in a sensitized individual can trigger acute asthma attacks — and high outdoor spore counts have been associated with emergency room visits for severe asthma exacerbations. If you have a positive Alternaria IgE and active asthma, this should be discussed with your treating physician or allergist. -
What foods should I avoid with an Alternaria mold allergy?
Some patients with Alternaria sensitization also react to mold-containing foods — particularly fermented foods (wine, beer, vinegar, soy sauce), aged cheeses, mushrooms, and certain fruits and vegetables with mold contamination. However, food triggers vary significantly between individuals and are not universal. This is worth discussing with an allergist if you notice symptoms after eating these foods. -
What is the difference between Alternaria IgE and Alternaria IgG?
IgE antibodies drive immediate allergic reactions (the mechanism behind hay fever, asthma, and anaphylaxis). IgG antibodies reflect exposure or immune tolerance and are not typically used to diagnose allergy. A positive Alternaria IgE indicates sensitization and potential for allergic symptoms. A positive Alternaria IgG (tested separately, M006-IgG) indicates exposure without necessarily indicating clinical allergy.
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