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How
the test is done
The
sweat test is a simple test that takes approximately one hour.
The
staff from the laboratory do this test, usually in the Children's
Outpatients Department.
The
first part of the test is to stimulate sweat production. This
is done by using a tiny electric current between two electric
pads that are loosely strapped to the child's forearm. Each
pad also contians a drug which stimulates sweating when it
touches the skin.
The
child may feel a tickling or tingling sensation or a feeling
of warmth - but it does not hurt and there is virtually no
risk of a "shock".
The
sweat is then collected in a tiny coil and analysed for the
amount of salt that it contains.
The
skin may stay red and sweaty for a couple of hours - this
is quite normal.
Sometimes
infants or young children do not make enough sweat for the
laboratory to test or for the result to be reliable. If that
happens the test may need to be repeated.
The
results of the test will be given to you the following day
by one of the doctors or nurses. If you have not heard please
ring the Outpatients Department.
The
majority of tests(90%) will come back as normal, thus excluding
cystic fibrosis.
However,
around 10% of the tests will show a raised salt level, most
showing intermediate levels of salt - not high enough to make
a diagnosis of cystic fibrosis, but not low enough to be absolutely
sure the child has not got cystic fibrosis.
For
these children we will need to repeat the sweat test, using
a different method, at Royal Liverpool Children's Hospital.
This will be organised for you a week after the test. Again
the majority of these tests turn out to be normal.
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