Be Aware of Class 6 Peanut Allergy

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Some people may have reactions when they come in contact with certain foods. These reactions are known as food allergies. Signs and symptoms of food allergies occur when people consume the food. These allergic reactions, that can vary from hives, rashes, and tingling mouth to the most severe anaphylactic shock, occur due to the presence of allergens (certain specific proteins) present within the food. The most common allergens in foods are the natural proteins present in cow’s milk, eggs, peanuts, wheat, soy, fish, shellfish and tree nuts.

What is Class 6 Peanut Allergy?

A person with an allergy to peanuts (or any other food) may be ordered to perform a Radioallergosorbent Test (Abbreviated RAST). A RAST consists in measuring the patient’s IgE antibody content in the blood against a specific test (IgEs are the substances secreted by the body as a consequence of allergens). If an allergy to peanuts is suspected then a RAST test for peanut allergen will be performed.

RAST tests report IgE content in units known as KU/L. The higher these RAST units the higher the content of IgE against peanut allergen and the higher the chance of having a reaction to peanut allergen (more allergic). RAST test have been reported in classes from Class 0 to Class 5 or 6. Class 0 means “no allergy” at all while 5 or 6 denotes “High Allergy or Severe Allergy”. A typical classification for RAST results is:

  • CLASS 0 (less than 0.35 KU/L)
  • CLASS 1 (0.35-0.7 KU/L)
  • CLASS 2 (0.71-3.5 KU/L)
  • CLASS 3 (3.51-17.5 KU/L)
  • CLASS 4 (17.51-50 KU/L)
  • CLASS 5 (50.01-100 KU/L)
  • CLASS 6 (greater than 100 KU/L)

A person with RAST (for peanut allergen) results greater than 100 KU/L is said to have a Class 6 peanut allergy, which means he or she is has a very severe allergy to peanuts, so this person can have severe reactions to peanuts even with traces of the peanut allergen.

Regarding allergy to peanuts it has recently come clear the relationship between RAST test results and the significance to the patient. For people who have never taken peanuts (for example a young child) a RAST result of only 1 KU/L would indicate a 50% chance that he or she will have a reaction to peanuts the next time he or she eats it. Patients with RAST values of 14 KU/L would indicate a 100% chance of having a reaction the next time they eat peanuts or products that contain it.

Anaphylaxis: A Serious Threat

A person with a Class 6 peanut allergy (severe allergy) has a 100% chance of having severe reactions to peanuts including anaphylaxis and even death if anaphylaxis is not treated immediately. Anaphylaxis is characterized by the following symptoms:

  • A red rash, with welts, that is usually itchy
  • Swollen throat or swollen areas of the body
  • Wheezing
  • Passing out
  • Chest tightness
  • Trouble breathing
  • A hoarse voice
  • Trouble swallowing
  • Vomiting
  • Diarrhea
  • A pale or red color to the face and body

Anaphylaxis requires immediate emergency treatment. People with Class 6 peanut allergy are recommended to carry an auto-injectable epinephrine (parents of kids with this class of allergy must learn how to use them). After using epinephrine, 911 must be called in for taking the person to an emergency room (sometimes there is a temporary recession of the anaphylatic shock with a secondary wave of symptoms coming after a while).


American Academy of Allergy. Asthma, and Immunology.

Jason Glaser (2006) .Food Allergies: First facts: Health matters, Capstone Press ISBN 0736863915, 9780736863919