Allergen Component Testing and Why you Should Order it for Your Patients

By: Alletess Medical Laboratory


With the holidays right around the corner, it could be a stressful time for your patients. Between pot lucks, office parties, and preparing for family gatherings, lurking in the back of your patients’ mind may be potential allergic reactions… If you suspect that your patient has an allergy, you should order them an IgE allergy test. If they test positive for an allergen, it’s very important that you dive deeper by testing the specific components of the allergen. 

After testing positive to a specific allergen, we tend to suggest Molecular Allergology testing, otherwise known as component testing, which tests proteins within an allergen, rather than the allergen as a whole. We understand that component testing can be difficult to understand, so we will answer some common questions about what it is and how it can help you.

What is component allergy testing and why should you care about it?

Component testing allows you to identify the specific proteins that can trigger an allergic reaction in your patients. The test contains a mixture of specific proteins which is combined with a blood sample and is observed for reactions to those specific protein compounds. This means that a patient could be allergic to only a certain protein within an allergen, and not the entire allergen

Nationwide has cited that over 6 million children in the U.S. have allergies. By understanding the specific protein reactivities, component testing can help individuals avoid other allergic foods or triggers with similar compositions. This form of testing can inform an individual whether the IgE levels are sensitivities or a true allergy, informing what types of precautions one should take. 

Check out some case studies below that describe examples of how component allergy testing works. 

Case Studies: 

Dog Allergy: 

A common example is being allergic to dogs. Wouldn’t it be nice to know that your patient is only allergic to a specific protein found in a male dog, and not a female dog? Instead of going through life thinking they can never own or be near a dog, component testing can allow you to give your patients the good news that they may be able to own a female dog, without any allergic reaction occurring! 

Wouldn’t it be nice to know that your patient is only allergic to a specific protein found in a male dog, and not a female dog?

Within the whole dog allergen, one of the most common proteins tested is rCan f5, which is a prostate specific protein. Reactivity to this protein may cause persistent rhinitis or asthma. Through component testing, if an individual is found to be primarily reactive to this protein, they may be able to own a female or neutered dog, because they do not release this specific protein. A 2016 study found that as many as 52.4% of patients were reactive to this protein and did not think they could be around dogs. Now, with the results of their allergen component test, they may have an option to own a dog! 

Peanut Allergy: 

Let’s look at the story of Tim, a young boy who experienced an itching and tingling sensation in his mouth after ingesting a granola bar. Due to his reaction, his parents assumed that Tim had a possible peanut allergy. To be safe, Tim’s pediatrician advised his parents to undergo a peanut-free diet for their child. A year later, Tim went back to his doctor for an allergy test, to confirm or rule out his presumed peanut allergy. 

After looking at his medical history and performing an examination, Tim’s doctor orders him a whole allergen test, as well as an allergen component test. The results showed that Tim was positive to a protein called Ara h 8, which is associated with localized reactions such as a tingling or itching sensation in his mouth. Since Ara h 8 is associated with localized reactions, Tim’s doctor could now understand that he has a very low risk of a systemic allergic reaction, like anaphylaxis. Interestingly, with the results from his allergen component test, Tim’s doctor speculates that he is actually sensitized to birch pollen, which has a high cross reactivity to Ara h 8. This means that his reaction was due to an allergy to birch pollen, rather than peanuts within the granola bar. 

From these results, Tim underwent an oral food challenge with peanuts, under the supervision of his doctor. Tim, his parents, and his doctor were all thrilled when Tim passed his oral food challenge and had no reaction to ingesting peanuts! From that day forward, Tim has been able to enjoy a PB&J safely! 

Egg Allergy: 

The figure below shows component testing for two patients, which takes components of proteins found in eggs and analyzes immune reactions to these specific components. If you look at the results, you will see that Andrea and Sylvia have similar results when comparing the whole egg white. However, if we look at ovomucoid, which is heat resistant and does not degrade when baked, Andrea has a much lower reactivity than Sylvia. Andrea’s low reactivity means that she can likely eat eggs when they are baked whereas Sylvia has a high reactivity and should avoid eggs of all forms. To confirm if Andrea can tolerate baked eggs, she should undergo a food challenge with her doctor before eating them without a specialist present. 

For Sylvia, she should take more precautions given the severity of her allergy and perhaps look for egg alternatives. In the case of Andrea, her low reactivity to this protein means that she should be able to live a less restrictive lifestyle and should be able to tolerate eggs when they are baked at a high temperature. Enjoy your cake, Andrea! 


Allergen component testing gives you, the doctor, more information about your patient’s specific allergy. By having a conversation with your patient after receiving the results, it can help determine what precautions should be taken. For example, for a very severe allergy, individuals should carry an epinephrine pen around with them in case of anaphylaxis. However, other individuals may only experience a rash if their allergy is less severe, all depending on what components they tested positive to. 

For individuals with allergies, who doesn’t want to know the fullest extent of knowledge about their allergy? Allergy component testing can do just this, by allowing individuals to understand certain situations or foods that may trigger their allergy due to similarities in protein structure. By understanding the full picture of one’s allergy, it can help prevent allergic reactions, and help your patients live a better life.