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'Allergy Testing' Category Archives

Allergy Tests for Eczema

Parents often ask us if their child with eczema is allergic to something in the belief that removing the allergic “cause” would clear the eczema.

Allergy Tests for Eczema
Allergy Testing for children with eczema may not be necessary

Unfortunately, it is not that simple. It is very rare for childhood eczema to clear after removing or reducing a possible allergen. However, allergies are more common in children with atopic eczema than in other children, so it is helpful for you to think about whether your child might be reacting to something.

Allergies in children with eczema may be:

  • Foods – most commonly egg and milk in the first year of life or peanuts in older children
  • Things in the air (airborne allergens) eg. grass, animal hair
  • Things in contact with the skin (contact allergens) eg plasters, preservatives found in some creams .

Things that make eczema worse (“flare”) are called “triggers”. Eczema often flares in response to several triggers happening at the same time rather than one at a time.

Triggers may be allergic in nature, but more often than not, they are non-allergic and include irritants, soaps, stress, heat, tiredness, sweating, changes in weather and having a cough or cold. Therefore it is only sometimes that allergy tests help to get better control of your child’s eczema.

In the case of eczema affecting the hands, the most common reason for worsening eczema are the irritant effects from contact with water, soap, sand, play materials, saliva, foods and cold wind. These effects are not allergic ones.

The best way to find out if there is something which causes your child’s eczema is to take notice of the reactions your child has. For example, if your child gets itchy patches and swellings on their skin after stroking a cat they do not see often, along with sneezing and a runny nose, then these are fairly reliable signs that your child is allergic to that particular cat.

Food allergies are sometimes harder to spot. If your child gets immediate ‘hives’ or a nettle rash on the skin or tingling in the mouth when eating a particular food, it is very likely they are allergic to that food. Blood or skin prick tests can be done to confirm this. (See details of these tests below.)

Remember that atopic eczema is a condition that comes and goes quite quickly and that the best time to look for allergies is when your child’s eczema is in a good and stable state.

Allergy Blood Tests

This blood test tells us if your child has antibodies in the blood which could react to common substances that spark off allergies. Blood tests are helpful to confirm a suspicion of an immediate food or airborne allergy. They can be helpful in babies less than 1 year old to look for allergy to milk and egg. Blood tests are helpful if they are negative to the suspected food as a negative test is pretty good at ruling out allergy. The blood test is also helpful if it is strongly positive when there is a history of possible allergy. More often than not, especially in older children, the tests come back as low positive which does not mean very much as lots of people without eczema are the same. In other words, what happens in the blood may have little to do with what happens in the skin. Sometimes, especially if your child also has asthma or hay fever, what happens in the blood is more related to those conditions.

Just to summarise then: a strong positive test can be helpful to confirm a suspected allergen. A negative blood test is sometimes helpful in telling us that your child is not allergic to something. A low positive or multiple low positive tests don’t help us a lot. For more information follow this link: https://www.allergyuk.org/diagnosis–testing-of-allergy/blood-tests

Allergy Skin Prick Tests

These are tests that involve pricking a tiny amount of liquid into your child’s forearm to see which ones react. Test liquids are made up out of things that may cause allergies. Drops of these liquids in very dilute form are put on to the arm and the skin is pricked with a tiny needle. If your child is allergic to a particular substance, then they will get a red swelling on their skin after a few minutes. To see a video of this process follow this link: http://www.allergyuk.org/diagnosis–testing-of-allergy/skin-testing

Like the blood test, skin prick tests are only really helpful if they are strongly positive or negative. Skin prick tests cannot be done on skin that is affected by eczema at that time. Anti-histamines must be stopped several days before skin prick tests.

Allergy Patch Tests

These are used to look for another kind of eczema called allergic contact eczema. Sticky patches containing various substances are placed on your child’s back. Contact eczema is very uncommon in babies with atopic eczema, but can occasionally occur in older children. It is much more common in adults. For example, someone may have hand eczema due to wearing rubber gloves as they have an allergy to rubber. The rubber substance will show up as a reaction on their back 2-4 days after placing the patches on. Unlike the positive tests for food and airborne allergens, identifying an allergic contact factor such as rubber, glue, perfume or nickel in jewellery offers a good chance of clearing the problem if that factor is avoided.

Allergy tests on the High Street

We would not recommend you having high street or internet allergy tests because there is no evidence of their value in the management of atopic eczema.

Final thoughts

If you have any questions about these tests or the information you have
read here, please talk to us at Elan Medical Skin Clinic.

Just remember that allergy tests are only part of the story when assessing your child for possible allergies.

Allergy tests, are they a waste of money?

Allergy testing has become increasingly popular over the years, in fact we see a lot of people at Elan Medical Skin Clinic who claim that they  have been diagnosed with certain food intolerances. But how reliable are these tests?

The medicines regulator (MHRA) has said there is no scientific basis for tests widely available in health food shops and pharmacies that claim to show food intolerances. In fact the MHRA found that there was “no scientifically valid test to diagnose food intolerance”. Many of the tests confirm the presence of IgG antibodies, which show only that a food has been eaten at some stage, not that someone is intolerant of it!

The MHRA said that attempting to self-diagnose a food intolerance or allergy using a test kit alone could potentially result in a delay in identifying or treating other medical conditions. It added that there was a clear distinction between food intolerance and food allergies, which can be potentially life-threatening.

So what should I do if I think my child has a food allergy?

Before you make big changes to your child’s diet or your own diet, it’s important to proper medical advice, so talk to your GP. If you or your child suffers from severe eczema, there are allergy specialist that you can be referred to on the NHS. If you GP is reluctant to refer, then book in to see Sue Ibrahim at Elan Medical Skin Clinic.

All forms of allergy testing, even when the results seem to be strong, must be considered together with a physical exam and a detailed patient history – both of which can help narrow down what food might be the trigger.

“You have to look at all the pieces of the puzzle because none of the tests by themselves are predictive enough of a diagnosis of a clinical allergy,” Sue Ibrahim says.

The physical exam and patient history also provide important clues, such as symptoms that could indicate whether or not a food allergy is the likely cause.

If you have hay fever you probably don’t need allergy testing as it may be obvious from your symptoms that you’re allergic to pollen. But it’s important to find out the precise cause if your symptoms are more complicated.

For example, perenial rhinitis, – a runny nose all year round – can be triggered by a variety of allergens, such as house dust mites and mould, or a food allergy could be triggered by one of a number of foods in your diet.

Allergy testing can also help monitor a diagnosed allergy. For example, babies and children with certain food allergies often grow out of them.

A test can let the parents and child know they no longer have an allergy to milk or eggs for example, so they no longer have to avoid that food.

Skin-prick testing (SPT) is the most common form of allergy testing and is used to try and identify the specific foods that a patient may be allergic to. Theses tests are only carried out at specialist medical allergy centres and if Sue Ibrahim thinks that you or your child should be referred to for allergy testing, she will refer you.

What is a skin prick test?

Drops of different serums containing individual allergens will be put the on patient’s forearm or back. A medical professional will then use a small needle to prick the skin – this feels like a small poke with a pin – so that the serum goes beneath the skin.

Skin Prick

Skin prick allergy tests are only ever carried out by medical professionals specialist allergy centres.

Then it’s a waiting game. The patient’s skin may react by forming a reddish hive, or wheal, at specific prick spots, indicating that the IgE antibodies in the skin responded to the food allergen in that serum.

A test is considered “positive” for a particular allergen if the diameter of the hive is 3 millimeters or greater than a prick site made with no allergen (known as the negative control). The bigger the hive, the more likely it is that you will react if you eat that food.

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