Rhizopus Nigricans (M11) IgE Biomarker Testing
It measures IgE sensitization to Rhizopus nigricans mold to support allergy evaluation and follow-up, with convenient ordering and Quest-based labs via Vitals Vault.
With Vitals Vault, you have access to a comprehensive range of biomarker tests.
This test looks for IgE antibodies your immune system may make in response to Rhizopus nigricans (also called Rhizopus stolonifer), a common environmental mold. A positive result does not prove you have “mold toxicity,” but it can support an allergy-style explanation for symptoms.
Rhizopus is often associated with damp indoor environments and decaying organic material. If your symptoms flare in certain buildings, seasons, or after water damage, a targeted mold IgE test can help you and your clinician decide what to do next.
Because IgE reflects sensitization (a tendency to react), your result is most useful when it is interpreted alongside your history, exam, and other allergy markers. Testing is a tool to guide clinician-directed care, not a standalone diagnosis.
Do I need a Rhizopus Nigricans M11 IgE test?
You may consider Rhizopus nigricans (M11) IgE testing if you have allergy-like symptoms that seem linked to indoor air or damp spaces. Common reasons include persistent nasal congestion, sneezing, itchy or watery eyes, post-nasal drip, chronic cough, or wheezing that worsens in certain environments.
This test can also be helpful if you have asthma or recurrent sinus symptoms and you are trying to identify triggers. If you have had water damage at home or work, visible mold, or a musty smell, a mold-specific IgE result can add objective data to the conversation.
You do not usually need this test for non-allergic symptoms such as generalized fatigue, brain fog, or body aches unless you also have clear respiratory or allergic flares. If you have severe reactions, trouble breathing, or signs of anaphylaxis, seek urgent care and work with an allergy specialist for a full evaluation.
This is a laboratory-developed specific IgE blood test performed in a CLIA-certified lab; results support clinical evaluation but do not diagnose allergy on their own.
Lab testing
Order labs to measure Rhizopus nigricans (m11) IgE
from $23.99 at Quest Diagnostics
About 1 week
Schedule online — results typically within a week
Clear next steps
Guidance included, with follow-up care available
HSA / FSA
Eligible for pre-tax health spending accounts
Get this test with Vitals Vault
Vitals Vault lets you order Rhizopus nigricans (M11) IgE testing without needing a separate referral visit, which can be useful when you are trying to clarify environmental triggers quickly.
After your blood draw, you can review your result in context and decide on next steps, such as adding a broader environmental allergy panel, checking total IgE, or planning a retest after exposure changes. If you want help making sense of what “positive” means for you, PocketMD can walk you through questions to discuss with your clinician.
If you are tracking symptoms over time, Vitals Vault makes it straightforward to reorder the same test so you can compare results under similar conditions (for example, before and after remediation or a move).
- Order online and complete your blood draw through a national lab network
- Clear, patient-friendly results with options to add companion testing
- PocketMD support for next-step questions to bring to your clinician
Key benefits of Rhizopus Nigricans M11 IgE testing
- Helps identify whether Rhizopus mold is a plausible trigger for your allergy or asthma symptoms.
- Adds objective evidence when symptoms worsen in damp buildings or after water damage.
- Supports more targeted environmental control steps instead of broad, guess-based avoidance.
- Can guide whether broader mold or environmental allergen testing is worth adding.
- Helps interpret confusing symptoms when skin testing is not available or not preferred.
- Provides a baseline you can compare if you retest after exposure reduction or treatment changes.
- Improves clinician conversations by separating sensitization signals from non-allergic “mold” concerns.
What is Rhizopus Nigricans (M11) IgE?
Rhizopus nigricans (often referred to as Rhizopus stolonifer) is a mold found worldwide, especially in decaying plant material and damp indoor environments. The Rhizopus nigricans (M11) IgE test measures allergen-specific immunoglobulin E (IgE) antibodies in your blood that recognize proteins from this mold.
IgE is the antibody class involved in immediate-type allergic reactions. If you are sensitized, exposure can contribute to symptoms such as nasal inflammation (allergic rhinitis), eye irritation, cough, or asthma flares. However, sensitization is not the same as clinical allergy: some people have detectable IgE but minimal symptoms, while others react strongly.
This test is one piece of an allergy workup. Your clinician typically interprets it alongside your symptom pattern, timing of exposures, other mold or environmental IgE results, total IgE, and—when appropriate—lung function testing or sinus evaluation.
Sensitization vs. allergy
A positive specific IgE result means your immune system has made IgE that can bind Rhizopus proteins. Whether that sensitization causes symptoms depends on your exposure level, your airway sensitivity (such as asthma), and whether other allergens are also driving inflammation.
Why the “M11” matters
“M11” is a laboratory code used to identify the Rhizopus nigricans allergen extract in specific IgE testing. It helps ensure you and your clinician are looking at the right mold target when comparing results across time or across panels.
What do my Rhizopus Nigricans M11 IgE results mean?
Low or negative Rhizopus nigricans (M11) IgE
A low or negative result means the test did not detect significant Rhizopus-specific IgE in your blood. This makes an IgE-mediated Rhizopus allergy less likely, but it does not rule out other molds, non-IgE mechanisms, or irritant effects from damp environments. If your symptoms strongly track with exposure, your clinician may still consider broader environmental testing or evaluation for asthma, chronic sinus disease, or non-allergic rhinitis.
In-range results (how “normal” is used for specific IgE)
For allergen-specific IgE, “normal” typically means below the lab’s positivity cutoff rather than an “optimal” physiologic range. If your result is below the cutoff and your symptoms are controlled, it often supports focusing on other triggers (dust mites, pets, pollens, other molds) or non-allergic causes. If symptoms persist, the next step is usually expanding the allergen picture rather than repeating the same single marker immediately.
High or positive Rhizopus nigricans (M11) IgE
A high or positive result suggests sensitization to Rhizopus mold, meaning your immune system recognizes it as an allergen. The higher the value, the more likely it is to be clinically relevant, but the number alone cannot predict reaction severity. Your clinician will weigh the result against your exposure history (damp buildings, musty odors, visible mold) and symptom timing to decide whether targeted avoidance, asthma optimization, or additional allergy testing is appropriate.
Factors that can influence Rhizopus IgE results
Your result can be affected by overall allergic tendency, including elevated total IgE or multiple concurrent sensitizations. Cross-reactivity between different molds can sometimes produce positive results even if another mold is the primary trigger. Recent changes in exposure (moving, remediation, seasonal humidity) can change symptom burden without immediately changing IgE levels. Medications like antihistamines generally do not suppress blood IgE results, but immune-modulating therapies and certain severe immune conditions can affect antibody patterns.
What’s included
- Rhizopus Nigricans (M11) Ige
Similar tests and related markers
Frequently Asked Questions
What does a positive Rhizopus nigricans (M11) IgE mean?
It means you are sensitized to Rhizopus mold, so your immune system has made IgE that recognizes it. Whether it is causing your symptoms depends on your exposures and your clinical history, so it is best interpreted with your clinician.
Can this test diagnose mold allergy by itself?
No. A specific IgE blood test supports an allergy evaluation, but diagnosis usually requires matching the lab result to your symptoms, timing, and exposures. Some people have positive IgE without meaningful symptoms.
Do I need to fast before a Rhizopus IgE blood test?
Fasting is not typically required for allergen-specific IgE testing. If you are combining this with other labs that do require fasting, follow the instructions for the full set of tests you ordered.
Will antihistamines affect my Rhizopus IgE blood test result?
Antihistamines usually do not change blood IgE levels, so they generally do not affect this test. They can affect skin prick testing, which is a different type of allergy test.
How is Rhizopus IgE different from total IgE?
Rhizopus IgE measures IgE directed at one specific mold. Total IgE measures the overall amount of IgE in your blood and can be elevated for many reasons, including multiple allergies, eczema, or some infections.
When should I retest Rhizopus-specific IgE?
Retesting is most useful when something meaningful has changed, such as moving out of a damp environment, completing remediation, or adjusting allergy/asthma management. Many clinicians wait months rather than weeks, because IgE patterns often change slowly.
What other tests are commonly ordered with mold-specific IgE?
Common companions include a broader mold IgE panel, other environmental allergens (dust mites, pet dander, pollens), and sometimes total IgE. If asthma symptoms are present, lung function testing may be more informative than repeating IgE alone.