This test is done to measure the amount of chloride and sodium, salt chemicals in sweat. This helps to diagnose cystic fibrosis. Generally, sweat has very little of chloride and sodium, but people with cystic fibrosis have a lot more of it in their sweat.
During the sodium chloride sweat test, a medicine that increases sweating is applied on the person’s skin, and the sweat is collected on a gauze pad or paper. This is then tested in the laboratory. The chloride in the sweat is measured in this test.
Sweat chloride testing is often conducted on a baby who might have cystic fibrosis. A test like this can be carried out even when the infant is 48 hours old. However, this test might have to be repeated as small babies do not produce a lot of sweat.
The chloride sweat test can diagnose cystic fibrosis and can be carried out to check the family history of cystic fibrosis or test people who are showing symptoms of cystic fibrosis.
There isn’t anything special or out of the ordinary that you have to do for this test. You can drink, eat and exercise as usual. Medicines (if being taken) should be taken at the usual time.
If the test is being done on a baby, then it is done on the right thigh or arm. If the child is older, then it can be done on the inner part of the right forearm. It is also possible that sweat can be collected from two different parts of the body.
After the area is washed and dried, a couple of small gauze pads are placed on the skin. One of these pads is soaked with pilocarpine, a medicine that will make you sweat. The other one is soaked with salt water. Then electrodes are placed on the gauze pads and hooked to an instrument that pushes this medicine into the skin. The sweat is collected into a coil using another technique. After sometime everything is removed and the skin is washed and dried. Remember that the area where this test was done will look red.
Then a paper collection pad or dry gauze pad is taped to this part of the skin and covered with wax or plastic to prevent the loss of fluids. This pad will soak up sweat, and after that it is put in a sealed bottle. This is tested to see how much of salt chemical is there in the sweat. The skin is washed and dried again.
It is a painless procedure.