An Original Article By:

Klinik Dr Shah 

Dr.Shahjahan Bin Kassim Mbbs, Di Derm (Lon), Msc Alelrgy (Imperial)

How Can We Test For Allergies

       

       Yes, allergies are a common occurrence. It can manifest in many forms such as on skin(Eczema), respiratory(Rhinitis/Asthma) and even our digestive system(Gut-food allergy).

As almost anything can cause an allergic reaction, it can be frustrating form patients who often suffer silently for years.

        Consulting an allergist (allergy doctor) is a good first step to find out the allergies we have; how to avoid them & how to best manage it. Some allergies may disappear spontaneously after weeks or months while others may be persistent. In addition, allergy may be from an Exogenous-outside origin ( dust mite allergy) or it may an Endogenous (from within our body-immune system overdrive)

In addition, an allergic reaction may be caused by a single or multiple allergens. All of these factors make it a challenge for your doctor to arrive at a diagnosis from a single visit. Let's take a  look at what tests are available in Malaysia and its pros & cons(if any):

TEST	REMARKS
Allergy History	The most important step in narrowing the search for allergens
Physical Examination	Again- a vital step to identifying allergy location, severity and possible other underlying immune disorder
Allergy Test- Skin Prick Test	Accurate method to confirm or rule of if you have a specific allergy- can perform up to 20 allergens at a time. Pros: 1. It’s a painless procedure and may 2. Test within  20 minutes.       3.Results are read the same day
Blood Test(Specific IgE antibody)	Blood Test is done as a screening test of allergies when we can’t identify the suspect allergen.       Pro:  Many tests can be done(>100 test)     Con:-             -Not as accurate as the skin test -         Higher cost -         Results may take up to a week
Skin Patch Test	Test to identify chemical & metal allergies Allergens are applied on the skin directly and results are read after 48 hours Pro: Accurate                                   Con: can’t be done is patient has extensive eczema
Challenge Test	If skin & blood test is not conclusive - a challenge test is performed. Suspected food or allergen is either applied on the skin; inhaled or ingested in front of medical personal to record the allergic reaction. Done only in limited conditions. Best done in a hospital with an emergency facility.

          Skin prick test is relatively simple and easy to perform when the reagents are available (watch the video)

Hence, there are many tests available at Allergy clinics that help identify what our allergies are and how we can avoid them. Allergy avoidance will definitely improve the allergy symptoms such as asthma frequency and improvement of skin texture of an eczema patient.

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Urticaria - Hives & Angioedema

What are they?
Hives (urticaria) are sudden breakouts of intense red often blotchy skin swelling. They can occur almost anywhere on the skin surface (including scalp) but occur most commonly on limbs and trunk.
They vary in size from mico dots to large discoid shape. The hive surface may be hot and itch intensely, and in some cases may burn and sting. Scratching may worsen the itch. The reactions last for a few minutes to a few weeks. Rarely, they last more than 6 weeks (chronic hives). It's said that acute urticaria affects 20% of the world population at least once in their lifetime.
Patients suffering from hives suffer through the day and night, losing sleep and are often frustrated and even depressed.

What Causes Hives?
The swellings in an acute episode usually come on within a few minutes and last for a few hours, only to completely resolve (disappear) within hours. So what happens during an episode? Disregarding the trigger(s), there are a series of events that occur within our immune system. The primary event is the release of an inflammatory (swelling) chemical called Histamine by our immune system. When an allergen (Eg dust mite protein) comes into contact with the immune system, it triggers a chain reaction within the immune cells (namely the mast cells), which results in the release of Histamine (Simplified explanation).
Histamine, in turn, causes the tiny blood vessels (capillaries) just under the skin to dilate that causes local skin cells to retain fluid (swelling/heat). Histamine also stimulates the skin nerve endings that cause intense itchiness. Scratching causes more tissue swelling and thus more itchiness.
 Possible causes of hives:

1. Foods                                                Milk, Egg, Nuts, Seafood, Fruits, Spices
2. Drugs                                                Antibiotics, NSAID(painkillers), ACE inhibitors
3. Viral Infections                                 
4. Insect Stings
5. Allergens                                          House Dust Mites, Cat/Dog/Rabbit Furs,
6. Others                                               Stress, Temperature change, Autoimmunune disease
7. Idiopathic                                         Unknown cause

What is Angioedema?

Angioedema is swelling of deeper tissues of skin - namely the subcutaneous and mucose membranes. It's easily seen where there is thick layers of subcutaneous tissue such as around eye socket (orbit) and lips. When an allergic reaction is severe it may involve the tongue and throat which may lead to breathing difficulty.

 What test can I do?

First of all, seek out a doctor who treats allergic disease. Diagnosing urticaria involves a detailed medical history taking, blood tests of the immune system and the allergy tests where appropriate.
The doctor may ask the patient to keep a medical log on timing of urticaria in relation to food, allergy exposure and frequency of episodes.
In some cases, the allergy doctor may conduct a skin prick or a patch test of different allergens to determine sensitivity.

Is there treatment available?

Urticaria may spontaneously remit after a couple of weeks in some cases. Here, the doctor's main aim is to control symptoms such as itch and redness. He may recommend antihistamines and corticosteroids to keep histamine action to a minimum. In persistent urticaria, the doctor may run deeper blood analysis on the immune system to determine if the urticaria is part of a bigger autoimmune disease.
The use of biologic agents such as xolair (omalizumab) is gaining popularity in steroid-resistant urticaria. However, high drug cost remains a challenge for mainstream usage.