Isocyanate TDI (k75) IgE Biomarker Testing
It checks IgE sensitization to TDI isocyanate linked to workplace asthma or allergy, with easy ordering and results through Vitals Vault/Quest.
With Vitals Vault, you have access to a comprehensive range of biomarker tests.
This test looks for IgE antibodies to toluene diisocyanate (TDI), a type of isocyanate used in products like polyurethane foams, coatings, adhesives, and some industrial processes. A positive result can support the idea that your immune system has become sensitized to TDI.
Because isocyanate exposure is often work-related, results are usually interpreted alongside your symptoms and your exposure history. The goal is not just “a number,” but clearer documentation for occupational health decisions, including exposure controls and follow-up testing.
A blood IgE result cannot diagnose asthma or prove that TDI is the only cause of your symptoms. It is one piece of evidence that can help guide next steps with workplace safety teams and clinicians.
Do I need a Isocyanate TDI (k75) IgE test?
You may want this test if you develop symptoms that seem tied to work around polyurethane, spray foams, paints/coatings, adhesives, or other isocyanate-containing materials. Common patterns include coughing, wheezing, chest tightness, shortness of breath, or nasal/eye irritation that improves on weekends or vacations.
It can also be useful if you have unexplained “new” asthma as an adult, repeated bronchitis-like episodes after certain tasks, or skin reactions (such as hives or dermatitis) that flare after handling specific chemicals. If your workplace requires documentation for exposure evaluation, a specific IgE test can be part of that record.
You do not need this test for routine seasonal allergies unless you have a credible isocyanate exposure history. If you have severe breathing symptoms, faintness, or swelling of the lips/tongue, seek urgent care rather than waiting on lab testing.
Testing works best when it supports clinician-directed care and workplace safety planning, not as a stand-alone self-diagnosis.
This is a laboratory-developed specific IgE blood test performed in a CLIA-certified lab; results must be interpreted in clinical and occupational context and are not a stand-alone diagnosis of allergy or asthma.
Lab testing
If you need documentation for workplace follow-up, you can order the Isocyanate TDI (k75) IgE test through Vitals Vault.
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
If you are trying to connect symptoms with workplace exposure, you usually need two things: a documented lab result and a clear way to interpret what it does (and does not) mean. Vitals Vault lets you order the Isocyanate TDI (k75) IgE test and complete your blood draw through a national lab network.
After results are posted, you can use PocketMD to review your report in plain language and generate a focused list of follow-up questions, such as whether your pattern fits occupational asthma, whether additional allergen testing is reasonable, and what to discuss with occupational health.
If your result is positive or your symptoms persist despite a negative result, you can use the same workflow to plan a repeat test after exposure changes, or to broaden evaluation (for example, with additional environmental IgE testing) so you are not guessing what is driving symptoms.
- Order online and complete your draw at a participating lab location
- PocketMD helps you translate results into practical next steps
- Designed for trending and documentation when repeat testing is needed
Key benefits of Isocyanate TDI (k75) IgE testing
- Helps identify IgE sensitization to TDI when symptoms seem linked to specific job tasks or materials.
- Adds objective documentation that can support occupational health evaluations and exposure-control decisions.
- Can help distinguish “work-triggered symptoms” from unrelated seasonal/environmental allergies when history is unclear.
- Guides whether it is worth expanding testing to other allergens or other isocyanates based on your job setting.
- Supports monitoring over time if exposure controls, PPE practices, or job duties change.
- Helps you and your clinician decide when to pair lab findings with spirometry or bronchial challenge testing.
- Creates a clear, shareable lab record you can review with PocketMD before workplace or specialist appointments.
What is Isocyanate TDI (k75) IgE?
Isocyanate TDI (toluene diisocyanate) is a reactive chemical used to make polyurethane-based products. In some people, repeated exposure can lead to immune sensitization. This test measures “specific IgE,” which is a type of antibody that can be associated with immediate-type allergic reactions.
The “k75” label is the laboratory allergen code for TDI in specific IgE testing. A detectable k75 IgE suggests your immune system recognizes TDI as an allergen. However, isocyanate-related illness is complicated: some people develop work-related asthma through non-IgE mechanisms, and some people with detectable IgE may not have clear symptoms.
Because of that, this test is most informative when you interpret it alongside your exposure timeline (what you handle, how you handle it, ventilation, and PPE), symptom timing (during shifts vs away from work), and objective lung testing when indicated.
How this differs from “total IgE”
Total IgE is a broad marker of allergic tendency and can be elevated for many reasons. TDI (k75) IgE is targeted: it asks whether you have IgE antibodies that bind to TDI-related allergen components used in the assay. You can have normal total IgE and still have a positive specific IgE, or vice versa.
Why occupational context matters
Isocyanates are common in certain industries, and exposure can occur through inhalation or skin contact, especially during mixing, spraying, curing, or cleanup. Even small exposures may matter if you are sensitized, so the combination of symptoms plus exposure history often drives decisions more than the exact numeric value.
What do my Isocyanate TDI (k75) IgE results mean?
Low or undetectable TDI (k75) IgE
A low/negative result means the lab did not detect IgE sensitization to the TDI allergen used in the assay. This lowers the likelihood of an IgE-mediated TDI allergy, but it does not rule out work-related asthma or irritation from isocyanates. If your symptoms strongly track with work, your clinician may still recommend spirometry, peak flow monitoring across work vs off days, or referral to occupational medicine or allergy/pulmonology.
In-range results (lab-reported reference range)
For specific IgE tests, “in-range” typically means below the lab’s positivity cutoff. If you are below the cutoff and feel well, no action may be needed beyond routine exposure precautions. If you are below the cutoff but symptomatic, treat the result as one data point and focus on timing patterns, exposure controls, and objective lung testing rather than assuming the problem is “not real” or “not work-related.”
High or positive TDI (k75) IgE
A positive result suggests sensitization to TDI and increases concern for an IgE-associated occupational allergy picture, especially if symptoms worsen during or after exposure. It does not, by itself, confirm occupational asthma, predict reaction severity, or prove that TDI is the only trigger. A positive result usually supports taking exposure reduction seriously and discussing next steps such as spirometry, serial peak flows, or specialist evaluation, particularly if you have wheeze, chest tightness, or repeated flares.
Factors that can influence TDI (k75) IgE results
Your result can be affected by how recently and how intensely you were exposed, because sensitization can evolve over time. Cross-reactivity and assay differences can also matter, since isocyanates are a chemical family and different tests may use different allergen preparations. Medications like antihistamines generally do not suppress IgE blood test results, but immune-modulating therapies and major changes in exposure may affect trends. Finally, symptoms from isocyanates can be irritant-driven or non-IgE-mediated, which is why lung function testing and exposure assessment may be needed even with a negative IgE.
What’s included
- Isocyanate Tdi (K75) Ige
Frequently Asked Questions
What does a positive TDI (k75) IgE test mean?
It means your immune system has detectable IgE antibodies that react to the TDI allergen used in the test, which supports sensitization. It does not by itself diagnose occupational asthma or prove TDI is the only cause of symptoms, so it should be paired with symptom timing, exposure history, and often lung testing.
Can you have isocyanate asthma with a negative IgE test?
Yes. Some isocyanate-related asthma is not IgE-mediated, and some symptoms are irritant-driven. If your breathing symptoms reliably worsen at work and improve away from work, your clinician may still recommend spirometry and serial peak flow monitoring even if TDI (k75) IgE is negative.
Do I need to fast for the Isocyanate TDI IgE blood test?
Fasting is usually not required for specific IgE testing. If you are combining this test with other labs that require fasting, follow the instructions for the full order.
Will antihistamines affect my specific IgE result?
Antihistamines typically do not change IgE antibody levels in the blood, so they usually do not affect the result. They can affect skin-prick testing, which is different from a blood IgE test.
How is this used for workplace documentation or PPE decisions?
A documented positive specific IgE can support the case for sensitization and may strengthen recommendations for exposure reduction, engineering controls, and task reassignment when appropriate. PPE decisions should be made with occupational health and safety professionals, because proper selection and fit depend on the specific process and exposure route.
Should I also get spirometry or see a specialist?
If you have wheezing, chest tightness, shortness of breath, or recurrent “bronchitis” episodes tied to work, spirometry is commonly the next step regardless of IgE status. Referral to occupational medicine, allergy/immunology, or pulmonology is often appropriate when symptoms persist, when you need formal work-related asthma evaluation, or when job modifications are being considered.