Paediatric Allergy
Tests alone do not diagnose
allergies accurately because
all tests have limitations and
misleading results are common.
Allergy tests have to be
interpreted in context of the
situation or reactions that
has occurred leading to
allergies being suspected.
Diagnosing allergies involves
a careful and focussed history
including the exact symptoms
observed and the exact
sequence after being exposed
to the trigger. It is often
helpful to bring a list of
foods or other possible
substances that could have
caused the reaction. Allergy
tests are most useful to
confirm a clear history of an
immediate allergic reaction
when a positive test result
can support the clinical
diagnosis. Allergy tests
should not be done as a
“fishing” exercise especially
if the trigger or food has
never been tried because the
results are commonly wrong
indicating an allergy is
present when actually there is
none, or wrongly concluding
there is no allergy only for
that person to suffer an
allergic reaction when exposed
to that food or substance.
Skin prick tests should be
avoided in patients with
widespread eczema where false
positive allergy tests
commonly arise or those taking
antihistamines or steroid
tablets. Sometimes blood
testing will be done as an
alternative. Many people
confuse allergies with
intolerance. Allergies affect
the immune system and can
cause a variety of reactions
including delayed
gastro-intestinal symptoms to
acute anaphylactic shock.
Intolerance is the inability
to digest a particular food
causing symptoms such as
nausea, vomiting and abdominal
pain. High Street companies
sell expensive tests that
often cost several hundred
pounds claiming to be able to
accurately diagnose allergies
and intolerances. These tests
do not have any proven medical
or scientific worth and give
inconsistent results. They
include analysis of blood
samples, strands of hair,
changes in electric current
(electrodermal testing) and
resistance to pressure applied
to one’s legs or arms
(kinesiology). It is a
misconception that these tests
are harmless because they
misdiagnose food allergy in
many people who subsequently
risk their health by adopting
restrictive diets that are
unbalanced, unhealthy, lead to
nutritional problems and are
unenjoyable. It is Dr Ho’s
practice not to perform any
allergy tests or
investigations unless
clinically indicated avoiding
unnecessary discomfort and
excessive fees.
Dr Ho has received training in Paediatric Allergy and can provide accurate and practical advice for:
- Food allergies
- Cow’s milk protein allergy and intolerances
- Urticaria
- Hayfever and rhinitis
- Asthma
- Eczema
The preferred test for acute allergy is skin testing because it does not involve needles or blood tests and results are available in 15 minutes. If you suspect a food allergy to any fruits, vegetables or other food please bring a small sample with you. However, please do not bring any nuts, sesame, wheat, egg, milk and all airborne allergens which are provided. Please ensure your child has not taken any antihistamines for at least 4 whole days (96 hours) before skin prick testing because these medications interfere with the accuracy of the tests. Some over-the-counter cold and flu medications contain an antihistamine, so be sure to read labels carefully. If you are not sure if the medicine you have contains an antihistamine, ask your local pharmacist.
