Do you also sneeze often? Do you get a runny nose and itchy eyes when you touch a little dust or a pet? Or do you get a red, itchy rash after eating a certain food, such as shrimp? You may have experienced these things too. These are what we simply call allergy symptoms . So, there is a special blood test that can help you find out exactly what is causing this problem and help your doctor choose the best treatment for it. That's what we're talking about today.
What are these blood tests for allergies?
Simply put, these blood tests measure the presence of a specific type of 'antibody' in your blood that is related to allergies. Think of it this way. When something that is not good for our bodies, that is, something that causes an allergy (we call this an allergen), enters our body, our immune system creates a group of special 'soldiers' to fight against it. We call these soldiers antibodies .
These antibodies go to certain cells in the body and tell them, "Here comes an enemy, release chemicals and attack." It is when those chemicals are released that we experience allergy symptoms, such as itching, skin rashes, sneezing, and difficulty breathing. The type of antibody that is mainly associated with the allergic response is called Immunoglobulin E (IgE) .
Typically, this blood test can test for about 10 common allergens in our environment at once. Examples include dust, pet dander, certain types of trees, grasses, weeds, and mold. These blood tests are especially useful for diagnosing food allergies .
What types of tests are these?
These blood tests are also called immunoassay tests. There are two main types:
- Enzyme-linked immunosorbent assay (ELISA, or EIA): This is the most commonly used and most modern method. It measures the amount of IgE antibodies specific to a particular allergen in your blood.
- Radioallergosorbent test (RAST): This was also a method used in the past. Now that the ELISA test has come along, it is not used as much.
Additionally, when you have an allergy, the number of eosinophils, a type of white blood cell in your blood, can increase. So sometimes your doctor may also order a test to check your white blood cell count. But remember, many other diseases can cause an elevated white blood cell count, so that alone is not evidence of an allergy.
Why do a blood test instead of a skin test?
Most of the time, doctors first turn to skin testing to diagnose allergies. But in some special cases, that's not possible. That's when this blood test becomes very important.
These are some of the situations where a doctor may recommend a blood test rather than a skin test.
- Some medications you are taking (e.g. antihistamines, steroids, some antidepressants) can cause skin test results to be inaccurate. If you cannot stop taking those medications for even a few days, it is best to get a blood test.
- During a skin test, the skin is scratched with a small pile of needles. This is a good option for those who cannot tolerate the pricking of needles .
- If you have a heart condition or poorly controlled asthma .
- If you have a condition such as severe eczema, dermatitis, or psoriasis , it may be difficult to perform a skin test.
- If there is a risk of a severe allergic reaction (anaphylaxis) to a skin test, or if you have had one in the past, a blood test is safer.
- It is easier to do a blood test than a skin test for small babies and very young children .
What are the advantages and disadvantages of blood testing?
Like any medical test, this one has both advantages and disadvantages. Let's look at it in a table.
| Advantages | Disadvantages |
|---|---|
| You can do this test at any time, regardless of what medication you are taking. | It is a bit more expensive than a skin test and may not be covered by some insurance plans. |
| Unlike a skin test, you don't get a bunch of needles. You only get a single needle to draw blood. This is convenient for those who are afraid of needles. | It may not be as sensitive as a skin test. |
| Best suited for babies and young children. | Since the blood sample needs to be sent to a lab for testing , it can take a few days or a week to get the results (skin test results are available immediately). |
How to understand the results?
This is a very important point. Understanding the results of this test can be a little complicated.
- A positive (+) result: This means that IgE antibodies specific to the allergen being tested were found in your blood. This is usually a sign that you have an allergy to that substance. However, there is a possibility that you may test positive for something but never develop any allergy symptoms.
- A negative (-) result: This means that you are not actually allergic to that substance. It means that your immune system is not reacting to that allergen. However, very rarely, it is possible to have an allergy despite a negative result.
Therefore, do not try to interpret this test report on your own. You should definitely show it to your doctor, talk to him, and compare it with your symptoms to come to an accurate conclusion.
Are there any side effects?
This blood test is very safe. The possible side effects are very minor.
- Swelling and redness at the site of the blood draw
- A little pain
- A little bleeding from the blood draw site
- As with any blood test, some people may feel faint.
Take-Home Message
- These blood tests help to find out exactly what is causing your allergy symptoms.
- This is a great option, especially in cases where a skin test is not possible.
- This has both advantages (being able to travel to get medicine, getting the job done in one go) and disadvantages (being expensive, taking a long time to see results).
- The most important thing: After receiving the test results, do not try to interpret them on your own, but definitely show them to your doctor (doctor), who is familiar with your symptoms, and get the right advice.
💬 අදහස් (0)
තවමත් කිසිදු අදහසක් පළ කර නොමැත. ඔබේ අදහස පළමු වරට මෙහි එක් කරන්න.
ඔබේ අදහස එක් කරන්න