The doctor wants your child to have a sweat test to find out if they have a condition called cystic fibrosis. This is an inherited, genetic disease that causes people to have a high amount of salt in their sweat.
Laboratory staff will only need a small amount of sweat from your child's skin to measure the amount of salt. In cystic fibrosis these levels are high. In a sweat test, the skin is stimulated to produce sweat to be absorbed into a special collector and then analysed.
A sweat test is a safe procedure that can cause a slight tingling sensation of the skin. It sometimes causes a slight irritation. Young children with sensitive skin may have a reddened area after the test is finished which disappears quickly after a few minutes.
There are no needles used in this procedure.
A sweat test usually happens in a laboratory but sometimes laboratory staff can do the test in a hospital ward. You can stay with your child during the sweat test.
Just make sure you don't put creams and lotions on your child's skin in the 24 hours before the test.
Keep your child warm before and during the sweat test to encourage them to sweat. Bring a warm sweater and woollen blanket to wrap around your baby during the sweat test. Older children will need a warm jacket or sweater to wear during the collection process. Bring something for older children to do (such as a book, colouring book etc). You will be able to feed your baby during the test.
The whole sweat test takes about an hour.
Sometimes it's difficult to collect enough sweat. Some children might need to have a second test. This usually happens on another day.
This page last reviewed 14 November 2022.
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