Making sick children better.
Making sick children better.
Dr John Chapman FRCPCH
Dr John Chapman FRCPCH
Consultant Paediatrician (NHS & Private)
General Paediatrics, Asthma and Allergy
Allergy Testing for Children in Norfolk & Suffolk
Allergy Testing for Children in Norfolk & Suffolk
My preferred method of allergy testing is Skin Prick Testing (SPT).
This involves placing a blob of bottled watery solution on the skin if the forearm (usually) and then making a small prick through the liquid into the skin. The solution contains a small amount allergen (grass pollen, cat spit, peanut etc) and this pricking method implants a small amount of it under the skin. Then, after carefully blotting (not wiping) the liquid off, we wait for about ten minutes to see if the skin reacts.
We also have some plastic "pain control" needles which allow eight allergens to be tested in a single prick which significantly reduces the child's discomfort and the time taken to do the testing.
No reaction in the skin makes allergy less likely.
A positive reaction produces a small bump (wheal or urticaria) as if you have been stung by a stinging nettle. It may be a little itchy, but not painful. The size of the bump (measured in millimetres) may give some indication of the severity of the allergy but this is not always the case.
Anything bigger than 3-4mm is positive. Some reactions can be up to 20mm. The wheal should disappear within 60 minutes.
Another similar testing method is Prick-Prick testing. In this method, the pricking lancet is first pricked into the allergen (usually food, especially fruit) and then into the skin.
We do this testing in clinic every week. your GP can refer you for testing via the NHS or I can arrange it privately for you.
Blood allergy testing (called specific IgE testing or RAST testing) is also possible and may be desirable in some cases. Blood testing can give false positive tests especially if the total allergy antibody (IgE) level is high.
ISAC 112 Allergen component testing (specific IgE in blood). Component testing takes allergy diagnosis to a new level. It is complicated and a bit difficult to get your head around, but, if you have complex allergies then it is well worth the effort. It tests for 112 components of over 50 different plant and animal proteins. it is now available privately and can even be done as a home test on a few drops of blood. Read more.
Whichever testing you have, the results MUST be assessed by a specialist.