Rat Epithelia (E73) IgE Biomarker Testing
It measures IgE antibodies to rat dander/epithelia to help assess allergy sensitization, with easy ordering and clear results through Vitals Vault and Quest.
With Vitals Vault, you have access to a comprehensive range of biomarker tests.
A Rat Epithelia (E73) IgE test looks for allergy-type antibodies (IgE) your immune system may have made in response to proteins from rat dander/skin cells (epithelia). It is a blood test used to assess “sensitization,” which means your immune system recognizes the allergen.
This test is most useful when your symptoms and exposures point toward rats—such as working with laboratory animals, living in a building with rodent activity, or having symptoms that flare in a specific environment.
Your number does not diagnose an allergy by itself. It helps you and your clinician connect the dots between exposure, symptoms, and other allergy testing (or avoidance steps) so you can make a practical plan.
Do I need a Rat Epithelia (E73) IgE test?
You might consider this test if you get sneezing, runny or stuffy nose, itchy/watery eyes, cough, wheeze, chest tightness, or eczema flares that seem to happen around rats or in places where rats may be present. Many people notice patterns at work (research facilities, veterinary settings, pet stores) or at home (older buildings, rodent infestations).
This test can also be helpful if you have asthma or chronic rhinitis and you are trying to identify triggers. Rat allergens can be airborne and can cling to clothing, so symptoms may show up even when you are not directly handling an animal.
You may not need E73 testing if your symptoms are clearly seasonal (suggesting pollens) or are strongly linked to other common indoor allergens (like dust mites or cats) and you have no meaningful rat exposure. In that case, broader inhalant allergy testing may be a better first step.
If you are already working with a clinician, your result can support clinician-directed decisions such as exposure reduction, workplace accommodations, or whether additional allergy testing is worth doing.
This is a laboratory-developed, CLIA-validated blood test for allergen-specific IgE; results should be interpreted with your symptoms and exposure history and are not a standalone diagnosis.
Lab testing
Order labs to measure Rat Epithelia (e73) IgE
from $21.99 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 Rat Epithelia (E73) IgE testing without needing to schedule a separate doctor visit just to access the lab. You choose the test, complete checkout, and then visit a participating lab location for a quick blood draw.
Once your results are ready, you can use PocketMD to get plain-language context for what “negative,” “low positive,” or “high positive” typically means, plus what follow-up questions to bring to your clinician—especially if you have asthma symptoms or workplace exposure.
If your result suggests sensitization, you can also use Vitals Vault to add companion tests (for example, other indoor allergens) or to retest later if your exposure changes or symptoms evolve.
- Order online and complete your blood draw at a national lab network
- PocketMD helps you turn a number into next-step questions for your clinician
- Easy re-ordering if you need confirmation or follow-up testing
Key benefits of Rat Epithelia (E73) IgE testing
- Helps confirm whether your immune system is sensitized to rat allergens when exposure is suspected.
- Supports identifying indoor or workplace triggers behind persistent nasal, eye, skin, or asthma symptoms.
- Provides an objective data point when symptoms are intermittent or hard to reproduce on demand.
- Can guide practical exposure-reduction steps (cleaning, PPE, ventilation, or pest control) based on evidence.
- Helps differentiate rat-related symptoms from other common indoor allergens that can look similar.
- Useful for tracking changes over time if your exposure increases, decreases, or you change environments.
- Pairs well with broader inhalant allergy testing so you can build a more complete trigger map.
What is Rat Epithelia (E73) IgE?
Rat Epithelia (E73) IgE is a blood measurement of allergen-specific immunoglobulin E (IgE) antibodies directed against proteins from rat skin cells and dander. IgE is the antibody class involved in immediate-type allergic reactions.
A positive result means your immune system has made IgE that recognizes rat allergens (sensitization). Sensitization increases the likelihood that exposure could trigger symptoms, but it does not prove that rat exposure is the cause of your symptoms. Some people have measurable IgE and minimal symptoms, while others have symptoms at lower levels.
This test is often used in occupational settings (for example, people who work with laboratory rodents) and in indoor air quality investigations when rodent exposure is possible. It can be ordered alone or as part of a broader respiratory/inhalant allergy panel.
Sensitization vs. clinical allergy
Think of sensitization as “your immune system recognizes it,” and clinical allergy as “you reliably react when exposed.” Your history—what happens to your nose, lungs, eyes, or skin after exposure—determines whether the sensitization is clinically meaningful.
How this differs from skin testing
Skin prick testing measures a local skin response to an allergen extract, while specific IgE is measured in blood. Blood testing can be useful if you cannot stop certain medications, have extensive eczema, or prefer not to do skin testing, but the best choice depends on your situation.
What do my Rat Epithelia (E73) IgE results mean?
Low or negative Rat Epithelia (E73) IgE
A low or negative result usually means rat sensitization is unlikely, especially if you have had regular exposure. If your symptoms strongly track with a specific building or job, a negative result can be a clue to look at other triggers such as mouse allergens, dust mites, cockroaches, molds, or irritants (smoke, cleaning chemicals). In some cases, timing matters—very recent exposure changes or early sensitization may not be captured on a single test.
In-range results (typical reference interpretation)
For allergen-specific IgE, there is not a single “optimal” target the way there is for cholesterol or thyroid markers. Many labs report results as negative vs. classes of positivity, and your clinician interprets that in the context of symptoms and exposure. If your result is reported as negative/in the reference range and you feel well around potential rat exposure, that combination is reassuring.
High Rat Epithelia (E73) IgE
A higher result suggests stronger sensitization to rat allergens and increases the likelihood that exposure could be contributing to symptoms. If you have asthma, wheeze, or chest tightness around exposure, this is a reason to take the finding seriously and discuss an exposure-reduction plan with your clinician. The number alone does not predict reaction severity, but higher sensitization can be associated with more consistent symptom triggering in real-world settings.
Factors that influence Rat Epithelia (E73) IgE
Your result is influenced by how much and how often you are exposed (workplace handling, contaminated clothing, building infestation), and by your overall allergic tendency (atopy), which can raise the chance of multiple positive IgE tests. Cross-reactivity can occur between related animal allergens, so a positive result may coexist with other rodent or pet sensitizations. Treatments like antihistamines do not typically lower blood IgE quickly, but long-term changes in exposure can shift results over months. Lab methods and reporting units can vary, so it helps to compare results from the same lab when trending.
What’s included
- Rat Epithelia (E73) Ige
Similar tests and related markers
Frequently Asked Questions
What does a Rat Epithelia (E73) IgE test detect?
It detects allergen-specific IgE antibodies in your blood that recognize proteins from rat dander/skin cells (epithelia). A positive result indicates sensitization, which may or may not match your real-life symptoms.
Do I need to fast for a rat IgE blood test?
Fasting is not typically required for allergen-specific IgE testing. If you are combining this with other labs (like lipids or glucose), those other tests may have fasting instructions.
Can antihistamines affect my Rat Epithelia IgE result?
Antihistamines usually do not meaningfully change blood IgE results in the short term, although they can affect skin testing. Always follow your clinician’s instructions, especially if you are doing multiple allergy tests.
If my Rat Epithelia IgE is positive, does that mean I’m allergic to rats?
It means your immune system is sensitized to rat allergens. Whether that is a true clinical allergy depends on whether exposure reliably triggers symptoms (nasal, eye, skin, or asthma) and whether other causes have been ruled out.
How is Rat Epithelia (E73) IgE different from total IgE?
Total IgE is a broad measure of all IgE antibodies and can be elevated for many reasons. Rat Epithelia (E73) IgE is targeted to one allergen source, so it is more useful for identifying a specific trigger.
When should I retest Rat Epithelia IgE?
Retesting is most useful after a meaningful change in exposure (for example, changing jobs, improved pest control, or new symptoms). Because IgE patterns shift over time, many clinicians wait several months before repeating unless there is a clear reason to test sooner.