Allergy Testing

ALLERGIES

Allergies can occur to anyone, anytime. Allergies can affect our daily activities and reduce our quality of lives.

Allergies occur when the body’s immune system reacts to a usual harmless substance (known as an allergen). Allergen normally do not cause any issues in most people, however, in allergic individuals, the body’s immune system identifies the allergen as a threat and mount an inappropriate response to it. This is known as an allergic reaction.

What are the Common Types of Allergies?

Allergies can occur in numerous types, affecting various parts of the body. Types of allergies include skin allergy, food allergy, hay fever, allergic rhinitis, eye allergy, insect stings allergies, latex allergy, pet allergies, and drug allergies.

Are Allergies in the Genes?

You may notice someone in your family has allergies too. Allergies can be hereditary. Allergies are more common in people with an atopy background, with a positive family and personal history of allergic rhinitis, eczema, and or asthma.

Though allergies are more common in children, it can happen at any age. Allergies can resolve over time, and recur many years later.

How do I know if I have Allergies?

Allergies affect various organs of our body.

In the skin, one commonly presents with itchy, red swelling particularly over the gravity-dependent region such as the mouth, lips, eyes, and may have rashes that appear nettled-like (hives) or eczema.

In the respiratory tract, one can develop sneezing, itchy runny nose, cough, wheezing or even breathlessness.

In the gastrointestinal tract, one can develop symptoms such as nausea, vomiting, abdominal pain, cramps or diarrhea.

In severe conditions, one may develop a full-blown allergic reaction that potentially be dangerous. One may present with acute difficulty in breathing, wheezing, throat swelling, lip and mouth swelling, eyes swelling, rashes and a drop in blood pressure. This tends to occur within minutes to hours after exposure to allergen. This condition is known as anaphylaxis. You should seek medical assistance immediately in such a dire situation, and it is advisable to carry emergency adrenalin pen for standby use.

How can I Treat Allergies?

Often, identifying and avoiding offending allergens that cause allergic symptoms are effective. Having said that, there are times when allergens are unavoidable as part and parcel of our lives. The use of medical therapies and having an emergency action plan for severe allergic reactions are important.

Medications that are useful against allergies include antihistamines, decongestions, and corticosteroids. These medications are used to alleviate allergic symptoms.

Immunotherapy is a preventive strategy for certain types of allergies. It works by allowing your body to be acclimatized and de-sensitized towards an allergy. This is performed by gradual introduction of allergic substances in an increasing dose into a person via oral, sublingual (under-tongue tablets or spray) or injection shots. Immunotherapy is particularly useful in allergies against dust mites, certain insect stings allergies, grass pollens.

Allergy Testing is offered to detect specific allergens. By identifying the culprit allergens, they can be avoided, preventing future allergic reactions. Allergy testing can be performed via blood tests or skin prick test.

Which Allergy Test is Suitable for Me?
Speak to your doctor about your individual concerns and allergy conditions. Your doctor will discuss in detail with you on the pros and cons of each test before advice further.

RAST Blood Test

This is a blood-taking procedure performed via your trained doctor or phlebotomist. The RAST blood test detects specific IgE antibodies produced against specific allergens. There is a wide range of allergen panels that can be tested through RAST IgE antibodies blood tests.

Is RAST Blood Test Suitable for Me?
You can consider if:

  • You are on medications that may interfere with skin prick test results, yet unable to stop the medications.
  • You have severe skin conditions such as eczema or psoriasis.
  • You have a risk of strong allergic reaction if you are exposed to the allergens via skin prick test.

How Long Can I Get my RAST Blood Test Results?

It takes approximately 1-2 weeks for the results to be ready after laboratory processing.

Skin Prick Test

This is a relatively simple, and accurate way of detecting an allergy. Skin Prick Test is a procedure performed over the inner forearm or the upper back of a person. It involves marking the tested skin area, following the introduction of allergens into the skin via small sterile needles that penetrates the skin surface. The test is later interpreted by your doctor for any evidence of raised red bumps and swelling.

What are the Common Side Effects is Skin Prick Test?
The test is offered in a clinic setting with close monitoring from your health care providers.
Most people tolerated the procedure well with minimal pain and without any bleeding, though some may experience mild itch and redness over-tested skin area.

Severe reaction to skin prick test is uncommon.

Is Skin Prick Test Suitable for Me?
Skin prick test is not suitable for

  • Those with a history of anaphylaxis to that particular allergens.
  • People with severe skin inflammatory conditions that affect most areas of their skin such as eczema or psoriasis.
  • One that is on oral antihistamine and is not able to stop prior skin prick test.

How Long Can I Get my Skin Prick Test Results?
This procedure takes approximately 20-30 minutes.

Do I Need to Stop my Allergy Medicine or other Long Term Medicine for Allergy Testing?

Some allergic medications (such as antihistamine- piriton, cetirizine, loratadine etc) can affect skin prick test results. Long term medications such as antidepressants may interfere the results as well. Please inform your doctor on all the medications that you are consuming.

How Accurate and Reliable is Allergy Testing?

When Skin Prick Test is performed correctly, it is relatively reliable. However, you may have a negative skin prick test, yet develop allergy later on in life. This is known as a false negative. There are a few explanations:
Your body may develop a new allergy over time due to repetitive exposure to the allergens.
You may be consuming certain medications that lead to a false-negative result.
Physician variability- Skin prick test is performed by doctors who are human with invariably slight deviation in their methods and skills.

RAST Blood Test has the edge of having a test result that is not interfered by medicine that the person is taking. However, there is a chance of false positive (A positive test, yet, the patient has no allergy symptoms when exposed to the allergen). This may cause unnecessary confusion and anxiety to patients.

How Often Should I Consider Allergy Testing?

It varies individually, depending on new onset of allergy symptoms and possible associated new allergen triggers.

Is Allergy Testing Covered by my Insurance?

You will need to check with your insurance company.

Afterword

Allergy Testing- worthwhile to proceed? Remember, allergy testing does not diagnose allergies. It should be interpreted prudently together with one’s medical condition and symptoms, and to aid diagnosing allergy.

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