Allergy blood tests assess the level of antibodies responsible for an allergic reaction in a sample taken from the patient. The entire procedure does not require skin contact with the allergen. This is important for people for whom skin tests are not recommended due to the risk of an anaphylactic reaction. The big advantage of diagnostic allergy blood tests is also the lack of the need to discontinue antiallergic drugs. What are blood allergy tests? What do the results of the study show?

Allergic blood testsare one of the diagnostic methods used in determining the type of allergy. They are based on the determination of the antibodies responsible for the allergic reaction.

The following are distinguished among blood allergy tests:

  • determining the overall level of antibodies, i.e. total IgE;
  • assessment of specific IgE levels, i.e. reactions to individual allergens;
  • screening tests using allergen panels.

Allergic diseases are currently classified as diseases of civilization. Their number in developed countries is still growing. It is estimated that allergies already affect more than 20% of the population. Symptoms related to allergic diseases significantly reduce the quality of life.

They can pose a serious threat to the he alth of the entire organism. A violent anaphylactic reaction related to an allergy sometimes leads to the death of the patient. Proper diagnosis of allergenic allergens enables their avoidance.

Allergic blood tests - diagnosis

Blood allergy tests are performed to assess the immune system's response to a variety of potential allergens. These substances are not harmful to he althy people. Unfortunately, the organisms of patients with allergic diseases recognize them as a potential threat. Contact with allergens triggers an irrational immune response, the symptoms of which are bothersome and harmful to he alth.

The substances causing allergic reactions are most often compounds with a protein structure originating from living organisms. These can be components of animal hair, pollen, products of fungi or bacteria. Sometimes allergens are also molecules that are not biological in nature, such as metals and drugs.

In the course of blood allergy tests, the immune response to such is checkedallergens like:

  • foods, e.g. cow's milk, eggs, soybeans, peanuts, fish or seafood;
  • pollen of plants, e.g. grasses and trees;
  • animal allergens e.g .: dust mites, hair, bird feathers,
  • drugs e.g. penicillin and salicylates,
  • insect venoms,
  • mold spores,
  • latex.

An allergic reaction can potentially be triggered by a huge variety of allergens. However, there are substances that statistically sensitize more often than others.

For this reason, allergy tests use basic panels with about 20 allergens belonging to one group. Such kits contain substances of similar origin, e.g. food or pollen.

Allergic blood tests - indications

  • nasal congestion
  • runny nose
  • tearing and conjunctival redness
  • skin blemishes
  • paroxysmal sneezing
  • feeling short of breath
  • wheezing

Allergic symptoms can occur at any age. Most of them are not very specific and may indicate the presence of other diseases. It is important to exclude infection and poisoning.

The first step to the correct diagnosis of the disease is to visit a specialist doctor. After careful evaluation of your symptoms, he or she may recommend allergy testing, including blood tests.

Allergic blood tests - when is it recommended to do them?

In the case of the previously described allergic symptoms, the doctor usually orders appropriate tests. Skin tests are the primary diagnostic method. In some cases, they are not recommended or do not give reliable results. Blood allergy tests are a good solution for such situations.

These tests are recommended when:

  • the patient cannot stop taking antihistamines,
  • changes in the body (e.g. atopic dermatitis, eczema, urticaria) disturb the results of skin tests,
  • the patient is pregnant, which is a contraindication to skin tests,
  • reduced skin reactivity in young children and the elderly,
  • reluctance of the patient to skin tests, resulting from an unpleasant procedure,
  • suspicion of an anaphylactic reaction in the patient during skin tests requiring direct contact with an allergen,
  • there is a suspicion of allergy to insect venom, which is a strong allergen and may cause severe anaphylactic reactions during skin tests,
  • there is a suspicion of food allergy in which skin tests are unreliableresults.

Blood tests are also ordered as the next step in diagnostics after basic tests are performed. Usually, such an indication is the inconsistency of the results of skin tests with the clinical picture of the patient.

Allergic blood tests - benefits

  • Easy procedure - the patient donates a blood sample without participating in the further stages of the allergy test.
  • Patient safety during the test - allergic blood tests do not require direct skin contact with the allergen. This eliminates the risk of a dangerous anaphylactic reaction.
  • The medications taken by the patient do not affect the test result.
  • No need to stop taking allergy medications prior to testing.
  • The test assesses the immune response towards a wide variety of allergens.

Blood allergy tests are an alternative to skin tests, which may be burdensome for the patient.

Allergic blood tests - course

The test begins with taking a blood sample from the patient. The ulnar vein is most often punctured. The test does not require any preparation, e.g. fasting. Then the sample is sent to the diagnostic laboratory, where total IgE or specific IgE is determined in the isolated serum. The procedure most often uses enzymatic (ELISA) or radioimmunoassay (RAST) methods.

The results obtained after the test has been performed must be presented to a specialist doctor. Only his in-depth analysis can be the source of the final diagnosis.

Information from blood allergy tests is ambiguous. A positive test result does not confirm that you are allergic to a given allergen.

Allergic blood tests - results

The results from allergic blood tests indicate the presence or absence of allergen-specific IgE antibodies. This helps determine the type of immune response to specific substances, such as food, pollen, and insect venom.

IgE level can be expressed in two ways:

  • using the concentration in kU / ml
  • in the form of classes corresponding to the concentration of antibodies. In this marking, 0 is their absence and 6 is a very high level. The higher the class, the more likely you are to have an allergy.

There are cases where the blood test results do not match the symptoms. Testing for specific IgE is only a guide for the doctor. A common mistake made by patients is self-interpretationdata.

In the blood allergy test for total IgE, you can determine if a patient is allergic. This study does not specify its types. Increased IgE levels indicate the presence of an allergic disease, but do not confirm it.

In assessing the patient's condition, norms are used, the exceeding of which suggests an allergy. They depend on age, for example:

  • newborns: 5-10 U / ml
  • children 7-10 years old: about 300 units / ml
  • adults: 100 units / ml .

Total blood IgE results are sometimes also reported using a 0 to 6 scale. The higher the score, the more likely the patient is to have an allergic disease.

Read also: Specific immunotherapy in the treatment of allergies

Category:

Allergies