|
Dr Du Toit will always obtain a rigorous clinical history prior to ordering allergy tests; allergy testing should never be performed in the absence of a clinical history. In young children it is important to realise that food allergy may masquerade as a ‘food aversion’. For example, babies with egg allergy may refuse - rather than react to - egg, thus asking, “does your child have egg allergy?” to the parents may be misleading, even if the parents answer “no”. The history aims to establish if the child can eat an age-appropriate quantity of the food. For instance, a non-allergic 5 year old child should be able to tolerate a peanut butter sandwich, a whole egg, a whole slice of bread, or a full glass of milk. Only if these criteria are fulfilled can it be said that the child is tolerant to that food. Dr Du Toit will also perform a physical examination to determine if your child growing well and to exclude signs suggestive of nutritional failure such as iron deficiency and rickets. The respiratory and dermatological examination will seek to document the presence or absence of concomitant allergic conditions such as asthma and/or eczema. Allergy Testing: There are only two scientifically validated allergy tests for the investigation of IgE-mediated food allergy; the Skin Prick Test (SPT) and Specific-IgE antibody testing (previously called RAST testing, now called Immuno-Cap Testing). Dr Du Toit makes use of both these tests. There are many other bogus allergy tests to be found on the high street or via the Internet - you should actively avoid these. Examples of tests that are not of any scientific value for the diagnosis of allergy include: Iridology, Vega Testing, IgG testing, Cytotoxic testing, Kinesiology... Allergy tests should only be undertaken using SPT's or IgE measurement. Tests should be performed to those ‘candidate food allergen/s’ identified on clinical history, this restricts the dangerous practice of testing to endless allergens that are already tolerated, or unlikely to be relevant allergens. Allergy testing is performed to ensure that the history correctly identified the cause of the index food reaction. Dr Du Toit will also perform testing to establish if the patient is co or cross-allergic to other food allergens, particularly if the patient has yet to eat these foods or if the foods were previously tasted but ‘disliked’. Dr Du Toit will also test to identify allergens which may influence the control of other allergic disorders; for example, pet dander allergy may exacerbate asthma which in itself is a risk factor for more severe food-induced allergic reactions. If a detailed history is unable to clearly identify a candidate allergen, then a screening allergen panel may be required. Screening panels should not be open-ended and should include allergens which are relevant to the patient’s age, allergic condition and geographical location. In practice, testing to peanut, tree nuts, egg white and cow’s milk will account for the majority of food allergies in young children. Wheat, soya and kiwi can be added to these panels, if not previously tolerated or eaten. In older children and adults, fin-fish, shellfish, kiwi and sesame should also be added to the panels, unless an unequivocal history of tolerance to these foods is obtained. There are distinct advantages and disadvantages when comparing Skin Prick Tests with Specific-IgE Blood tests. For example, Skin Tests provide an answer withing 30 minutes of testing whereas blood tests take some time longer to return. Skin Prick Test values can vary between centres whilst IgE tests are standardised. Some labile foods such as Kiwi, Lentil, Wheat, and Sesame perform better on Skin Testing when fresh uncooked forms of the foods are used. Specific-IgE Allergy blood tests are not influenced by concurrent antihistamine use whereas Skin Prick Tests are. It is difficult to test to many allergens on Skin Prick Testing, Specific IgE Allergy tests allow for testing to many allergens.
Allergy tests, both Skin Prick testing and Specific-IgE blood testing, are able to predict for the likelihood of future allergic reactions if accidental exposure were to occur, however, this testing cannot predict for the severity of these reactions. Allergen Component testing is increasingly of use in predicting for the severity of future reactions as well as the likelihood that the allergies have been outgrown. The use of allergy test predictive values significantly reduces the need for diagnostic dietary investigations. Supervised incremental oral challenge tests remain the gold standard investigation for the diagnosis of food allergy.
Frequently asked questions relating to Allergy Testing Allergy testing is undertaken in both clinics, based in South and North London; only validated allergy testing will be performed in these private specialist allergy clinics in London. IgE tests relies on circulating antibodies in the blood whereas Skin Prick Tests measure antibodies in the skin, these allergy tests are widely performed and are reproducible allergy testing modalities. Private Allergy Testing Clinics in London, UK.Predictive values of Allergy Tests, understanding allergy tests and performing allergy tests, clinics and London. Allergy testing in South West London, Private. Allergy Testing in South East London, Allergy testing in London, Private Clinic, UK. private allergy skin prick tests and private allergy bloods testing.Allergy testing in a professional clinic in London, catering for families living in South East London, South West London, south London and North London. Allergy testing for food allergies, London Clinics, Allergy testing for aeroallergies in London Allergy Hospital.
|
Allergy Tests, London |
