Medicine & Diagnostics

All questions & answers about science at igevia: allergies vs incompatibilities, differences in the test methods, advantages of IgE-testing.

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What is the difference between an intolerance and an allergy?

An allergy is a hypersensitivity reaction of the immune system to a foreign substance—an allergen (e.g. pollen, animal hair, house dust mite or a food). This so-called immunological reaction causes the formation of IgE antibodies and causes complaints such as mild itching, burning and swelling in the oral cavity to life-threatening circulatory failure. In cases of intolerance, the body cannot digest certain components of the food (e.g. lactose, fructose or histamine) properly, resulting in flatulence, abdominal cramps or diarrhoea.

What is IgE (immunoglobulin E)?

Immunoglobulin E (short IgE) is an antibody of type E, which is present in the blood in very low concentrations and plays a decisive role in allergic reactions and the associated detection of allergies. In allergy testing it is therefore important that the test procedure measures the presence of IgE in the blood.

How do skin tests and blood tests work?

When doing a skin test (allergy test on the skin, e.g. prick test), small drops of an allergen solution are applied to the skin (usually on the forearm) and then pricked into the skin with a small needle or lancet. If allergen-specific IgE antibodies are present, so-called mast cells are being activated. These then release messenger substances such as histamine and an itchy wheal develops at the skin site. In a blood test, a small blood sample is taken (e.g. from the fingertip) and analysed in the laboratory. Same as the skin test, allergen-specific IgE antibodies are detected in the blood. Both tests therefore search for IgE antibodies only at different locations.

What is the difference between skin tests and blood tests?

Tests play an important role in the diagnosis of allergies. Skin tests, such as the prick test, are widely used. However, modern allergy tests using small blood samples are the most advanced development.

  • Patients perceive blood tests as less stressful and time-consuming compared to skin tests.
  • Blood tests provide diagnostic findings that would not have been possible otherwise.
  • Cross reactions can only be detected with a blood test.

What characterises a high-quality allergy test?

A high-quality allergy test correctly detects the presence of IgE antibodies in different concentrations in a repeatable (reproducible) manner. A test for intolerance is not an allergy test - read the article "Difference between allergy and intolerance".

I have already done a prick test—does it make sense to additionally do a blood test?

A blood test can be useful if the previous prick test did not yield a reliable result. This may be the case, for example, if the prick test was influenced by medication (e.g. anti-histamines), the reaction was not reliably readable on the skin or the skin was hypersensitive. In addition, many more (different) allergens that are not available for skin testing can be tested in the blood test.

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