A walnut allergy occurs when the body’s immunoglobulin E (IgE) antibodies react with the protein components in a walnut. That reaction releases a pro-inflammatory mediator (histamine) that causes the manifestation of clinical symptoms. The severity of the allergic reaction differs between individuals. Some examples of mild symptoms include: Itching sensation in the throat or mouth Excessive sneezing Diarrhoea Conjunctivitis Difficulty in swallowing food While most affected individuals experience the symptoms listed above, clinical manifestations of a walnut allergy can sometimes be more severe. In such cases, patients suffer from dermatological conditions such as hives or eczema along with facial swelling and breathing difficulties. In rare circumstances, a walnut allergy can induce anaphylactic shock. The condition can be fatal if the affected individual does not receive immediate medical attention. Symptoms of anaphylaxis include: Unusual sweating or clammy skin Nausea and vomiting Blood pressure Rapid pulse Fainting or dizziness People allergic to walnuts can also have other variants of nut allergies. Allergenic components in nuts share cross-species similarities, which can induce the same hypersensitive reactions. This phenomenon is called cross-reactivity. Examples of nuts that have similar allergenic components as walnuts are: Almonds Pecans Pistachios Cashews Hazelnuts A walnut allergy test can diagnose allergic reactions to the protein components present in walnuts. Moreover, the nut allergy test can assess an individual’s potential response to other nut allergens. The assessment involves in-vitro serum testing, where the patient’s specimen reacts with the associated walnut allergens to form a complex. Testers remove non-specific IgE antibodies and add a labelled enzyme (anti-IgE antibody). After another removal process, the complex incubates alongside a developing agent. Fluorescent light is passed through the complex to assess the IgE antibodies in the sample. A high fluorescence value indicates an increased IgE concentration. Anything equal to or above the value of 0.7 ku/L leads to the diagnosis of a walnut allergy. A few factors can render a nut allergy test invalid. If an individual has received prior immunotherapy, it can reduce IgE concentrations temporarily and, thus, deliver false test results. Additionally, a person may not manifest medically significant symptoms but still have a measurable IgE concentration in their sample. In such circumstances, test results are interpreted in that specific clinical context. A walnut allergy test can also deliver false results if the patient specimen binds to non-specific antigens. Allergic reactions often aggravate existing respiratory issues. Hence, anybody with a history of such problems must seek immediate medical advice when they experience allergic symptoms. Apollo 24|7 offers a comprehensive walnut allergy test that can diagnose an allergic response to walnuts. Some other aspects that a nut allergy test can help with are: Determining the severity of the allergic response. Outlining necessary treatment options. Additionally, allergen response observed in a walnut allergy test can help doctors determine an individual’s cross-reactive sensitivity.     Medically reviewed by Dr Jatin Ahuja, Infectious Diseases, Apollo Hospitals Indraprastha, South Delhi.